Transcript for:
Comprehensive GCSE Biology Review

hi guys welcome to my all-in-one biology video and this is for edexcel GCSE and 9 to 1 I hope you find it super helpful as with aware that all in more videos I try and go through every single specification point all my pad for answers flash up and don't forget if you want to buy my revision guide which I have written containing my path answers you can get that on the website which will flash up now I hope you find this video super super helpful I hope your studies are going well don't forget to come follow me on insta to issue and Facebook because I add lots of extra exam tips extra explanations and just general cool science start particularly on insta so I really would recommend giving that ago and I do go through pass papers there too so yeah I hope you find this video helpful the let's get started so first of all our animal cell remember it looks like a fried egg basically it's got a big border and it's got a small compartment in the middle remember that compartment is the nucleus the nucleus controls the activities of the cells there's your key definition then you have some jelly which surrounds it and we call that the cytoplasm roll for that is that it's where all the chemical reactions take place that's another key definition surrounding with cell you have a cell membrane please note that there is no cell wall in an animal cell the only thing you have is a border a single water which is the cell membrane and that controls the entry and exit of substances inside the cell then you'll have to learn mitochondria that's really the powerhouse of the cell and it creates energy via aerobic respiration remember aerobic respiration means that it requires oxygen then you have some tiny dots these are fibrous ohms and they're responsible for protein synthesis moving on to the plant cell you find exactly the same structures in the plant cell nothing's missing we've just got a few additions and first we will make sure you're happy that a plant cell is very rectangular in shape and that's because surrounding it is the cell wall and that supports the cell rectangle in the middle called the vacuole that contains cells SAP and then we've got a nucleus squeezed into one corner again like the animal cell that control the activities of the cell we also have mitochondria but crucially we have some green things which look very similar to mitochondria but the fact that they're green houses that their chloroplasts and they're full of a pigment called chlorophyll which gives it its green color that's where photosynthesis takes place bacteria responsible for some of the most horrendous disease without they're things like tuberculosis they're bacterial diseases cholera is another one this time you've got more of a distinct cell you have a cell wall you have a little tail and we call that a flagella and that helps the bacteria move to where it wants to go sometimes you'll see diagrams with a capsule around the edge or a slimy coat that's just an additional structure don't worry too much about that the crucial thing about bacterial cell is that there's no distinct nucleus what you have instead is Luke Lloyd and then you'll see some tiny other structures in these are plasma plasmids and these are also genetic information and they're really important when we're talking about genetic engineering now some of these adaptations I think you can see they're not really distinctive other patients it's more about the fact that you're able to describe the cell in detail so I do recommend that you do shove it as many specialist words as possible by themselves now I like spam cells because they're really easy to remember first of all remember that they have a very characteristic shape they have a whiplash tail which helps them to swim they have a central portion which is packed full of mitochondria to provide energy to enable them to swim they have a head containing genetic information and lastly they have some enzymes in their head which help break down the outer casing on the egg when they need to penetrate it those enzymes are found in a special structure called the acrosome another very good specialist word so if I draw a very rough diagram of the female reproductive system remember that the egg cells are produced in the ovary and in terms of their specialism so how they're adapted for their function you need to learn the following they contain a haploid nucleus which really means they contain only one set of chromosomes and that will become much clearer later on in the video the cell membrane so this bit here becomes hard after fertilization so once the sperm has fused and while that's to prevent other sperm coming along and fertilizing the egg it has lots of cytoplasm which we know is where chemical reactions take place but the egg cell cytoplasm contains plenty of nutrients for the growth and development of the future embryo and lastly a jelly coat provides protection and again hardens after fertilization now we know that this egg gets deposited in the oviduct or the fallopian tube and this point here that I've marked with an X is where fertilization tends to take this at the entrance of the oviduct so what is special about the cells which line the oviduct well they have cilia so if i zoom in on one so these little cells this over duct and we zoom in on them and the cilia of really small hair type structures and they waft back and forwards and in this way when they walk together they can actually move that egg along the oviduct so that's how the cells lining the oviduct are specialized for their function linked with the cilia found in the oviduct are the cilia found in the trachea which as I've said here the trick here is the windpipe so you can see here's our windpipe or trachea and these are our ciliated cells complete with their small hairs and why do we have them well as we know we breathe in through our nose through our mouth and that air passes down the trachea however it's not a perfect system and sometimes pathogens and other particulates dust for example gets drawn in as well now we don't want those particulates ending up in our lungs so the amazing thing is is that there's mucus which traps the pathogens and the bacteria and it causes it to stick to the cilia and then as I said previously the cilia waft back and forwards and in this way they can actually move the pathogens out of our trachea into our mouths where it can be swallowed and destroyed by the hydrochloric acid found in our stomach so let's just quickly make a note on the ciliated cells we're going to use the same thing in order to help you remember these definitions because they there's a hierarchy they all build on each other so remember organelles are the small structures found inside cells so an example could be mitochondria could be nucleus it could be chloroplasts now a cell in that case therefore is a group of organelles working together to perform the same function and you're going to use those words to surround each of your answers now if that's not making sense I'll move on to the definition of a tissue and you're going to say it's a group of cells working together to perform the same function and then if you move on to an organ well it's a group of tissues working together for the same function and then lastly you've got an organ system which as you might expect is a group of organs working together to perform the same function so let's start by looking at the microscope so remember there are two microscopes you need to know about they are the light and electron microscope get those sorted in your head as to what they are the light microscope you find in your classroom you've obviously used it in science lessons I hope electron microscopes the ones you find in big scientific laboratories and they are very expensive so in terms of comparing how well they actually work look at the magnifying powers while light microscopes only magnified to two thousand times electron microscopes up to two million times then we'll look at the resolving power which is the ability to distinguish between two separate points like microscopes can only distinguish between points which are 200 nanometers apart electron microscope to the zero point two nanometers apart there are good things aren't like microscopes you can use living samples volectro microscopy they do very much have to be completely dead unlike microscopes you can see in color electron microscopes they will be black and white but we often see pictures which have been colored in or died now I'm going to show you how to use the magnification equation is your formula triangle that you need which is image size magnification and object size so obviously if you're looking for magnification you cover that so you see that it's image divided by object size if you're after image size then you just do magnification times object size and for object size you just do image divided by magnification and I always use this triangle here to help me remember when you're subbing in your numbers to the formula you've got to use the same units otherwise you'll screw up so I recommend converting everything to millimeters so to do centimetres to millimetres you take your number that's been given in centimeters and you times it by 10 if you've been given the number in micrometers then you want to divide it by a thousand I'll show you an example now so the image of a cell in a book is it's 48 centimeters in length however the real cell is only 120 micrometers calculating the magnification so I'm going to use the triangles to tell me that magnification is image divided by object then we need to get the image size into millimeters so I've been told it's 4.8 centimeters so according to my writing in black i need's times it by 10 to get it into millimeters so it becomes 48 and then we need to convert 120 micrometers which is fuzzy over here into millimeters by dividing 120 by a thousand which is how I've got 0.12 plug that into your calculator and you get an answer which is a magnification of 400 times that's a bit another question a student measure of the diameter of a capillary in a micrograph the image measures 5 millimeters and the student knows the magnification is times 1,000 how many micrometers is the diameter of the capillary using our formula triangle then we're after the object size so we're going to do object size equals image divided by magnification so I've written the equation here and then we're just going to pop those numbers in as they are so we're going to do five divided by a thousand which gives us a value of zero point zero zero five millimeters however it wants the answer in micrometers so therefore we need to do the opposite of my conversion so we're going 4 millimeters to micrometers this time so obviously we need to do the opposite of this which is times by a thousand so that brings the answer to five micrometers then enzyme is a biological catalyst this means that it speeds up the rate of a chemical reaction without being used up now an enzyme has a very special part on it called an active site and that's the biologically active part of the molecule and what happens is the substrate molecule binds to the active site it forms an enzyme substrate complex which then splits up to form a useful product that were after and we're going to talk now about the gesture of enzymes because I think it makes sense for us to look at the various products and substrates involved in digestion so their various enzymes you need to be aware of firstly amylase and notice the enzymes tend to end in a se so a x' amylase is made in the saliva glands in your small intestine and your pancreas and what amylase does is it catalyzes the breakdown of starch into glucose so in this case starch is the substrate is the thing entering the enzyme which is amylase and then the product here is glucose so what you can see is a very large sugar is broken down using amylase into a much smaller simpler sugar called glucose now we need to look at proteins this is more straightforward because as the name suggests it breaks down proteins so protein is the substrates and it breaks down proteins into amino acids these are the products and proteases found in your stomach in your small intestine and your pancreas the last enzyme you need to be aware of is lipase lipase breaks down lipids or fats as they're more colloquial name and lipids are broken down into fatty acids and glycerol so do try remember that's the most complicated one now we need to just touch on enzyme activity so the two things you can alter is both the temperature and the pH so if you look at this graph you can see at low temperatures the enzyme activity is low the reason for this is also to do chemistry is to do with collision theory because at low temperatures enzymes have very little kinetic energy as do the substrate molecules so it means that their enzymes on the substrate aren't coming very often that means they obviously can't find at the active site and so that you actually can't be catalyzed catalyzed catalyzed as we increase the temperature you can see the enzyme activity increases that's because those molecules that comers have them often and at 37° as is the case with most animals you will find that enzyme activity has reached its peak it is at its optimum temperature the best temperature and that means the enzymes and substrates are coming together very frequently after this temperature and above this temperature we see a massive decrease in enzyme activity and that's because the enzyme has become denatured never say the word killed they're not living they can't be killed you need to say that denatures we've all that means is that the enzymes active site has changed shape meaning that the substrate for no longer fit because he could look at pH now you can see a very distinctive graph shape here and that's because enzymes have different optimum PHS and if the pH is either too high or too low around the optimum pH you'll find that the enzyme denatures which is why you have that cone shape because let's look at the enzyme which has an optimum pH of 7 if you go to 6.5 or some point by the enzyme will denature and this is true for all enzymes some enzymes prefer different pitches to other ones so proteases in the stomach for example because they're swagged by hydrochloric acid they'll have an opportunity hm3 wearers to all the rest of the digestive system you find a slightly alkaline optimum pH server around 8 which is why you can't take stomach protease and put it in this one test and expect it to be ok so we're going to leap straight in we're testing for glucose now you want to use Benedict's reagent here and you're going to heat your sample with some Benedict's reagent in a water bath if glucose is present you will see a brick red color appear if it's not present then you'll just see the blue which is the Benedict's reagent and that is testing for glucose testing for starch is simplicity itself you simply add a drop of iodine now iodine will turn blue-black in the presence of starch it will stay like a yucky brown color if there's no starch that to test for proteins you're going to add by a rare agent biuret reagent I don't know if I'm pronouncing a right pass about it right now and what will happen if you've got protein is you will see a lovely move purple color where are you rushing off to Lyra and then lastly testing for facts you're going to use you motion test so first we will start by adding some ethanol to your sample which is a type of alcohol then you'll add some water if fat is present you will see a milky white emulsion or suspension and it will just go cloudy effectively now we're moving on to transport so let's first of all touch on the three types of transport so we're looking at diffusion osmosis and active transport so you need to know the definitions of these terms in great amount of detail now remember with diffusion is the net movement of particles from an area of high concentration to an area of low concentration so that's the reason why you spray perfume and one side of the room well there's a high concentration of packing particles and it moves the cross to the other side of the room where you can smell it that is by diffusion it is a passive process it does not require energy osmosis is very similar to diffusion however involves the movement of water which is why our definition this time is osmosis is the net movement of water from an area of high water potential to an area of low water potential across a partially permeable membrane now potential is just a really posh way of saying concentration so some one where there's lots of water to somewhere where there's little water and do you add that it's across a partially permeable membrane if there's no partial power your membrane it's not as mousses it's just diffusion so notice one more - leaves the stomata from that leaf that is by diffusion Co stomata is a hole not a part of the permeable membrane lastly active transport as the name suggests is an active process this means it requires energy the reason being is because it's the net movement from an area of low concentration to an area of high concentration so against the concentration gradient let's touch on amoeba now remember an amoeba is an example of a proton test this is a single-celled organism which can use diffusion in order to obtain all the nutrients it needs so oxygen diffuses from outside that amoeba into the amoeba from an area of high concentrations surrounding the amoeba to a low concentration inside the amoeba the reason why diffusion is appropriate is because it cars very quickly because the amoeba is single celled which means it has a large surface area to ratio and therefore the speed of diffusion is fast enough to allow oxygen in as and when it is required but larger organisms which are multicellular have a much smaller surface area to volume ratio diffusion is not suitable in is too slow which is why they developed the need for a circulatory system now we need to talk about the sales cycle so let's start by looking at chromosomes so remember that your DNA is found inside chromosomes which are found as pairs inside the nucleus of the cell and this is why we say that the nucleus controls the activities of this app now obviously for throughout our life ourselves don't just stay as old as we are because you'd have an issue of some very old worn out cells not doing their job properly so obviously they need to copy themselves and produce daughter cells ie new cells so we can carry on living and that's where the cell cycle comes in now remember that during the cell cycle all that genetic information is copied and that happens in mitosis and then it did the cell divides in order to form two daughter cells each with a full set of chromosomes now remember that in the cell cycle in order to produce those genetically identical daughter cells not only do we need to copy the genetic material but we need to produce new organelles so new mitochondria new cytoplasm new cell membranes obviously so that our daughter cell can be exactly the same as the original cell this is the type of cell division which produces clones so identical daughter cells and these are needed in the growth and repair of organisms so mitosis we know is a type of cell division and it's used for the growth and repair of cells and in order to grow and repair we obviously need to take our original cells and we need to multiply them so we've gone from one cell and we call this the parent cell and we've produced two daughter cells and remember in mitosis these will be genetically identical because they need to carry out the same roles but there are various stages of mitosis you need to know and I like to use peanuts to help me remember this so P stands for prophase M stands for metaphase a stands for anaphase and T stands for telophase and you need a brief summary of what happens in each stage and we know I can't draw but what we're going to do is here's my cell and I'm going to say that the nucleus has broken down in it and spindle fibers form so this is what happens in prophase then in metaphase what you find is that the chromosomes line up at what's called the equator so the middle part of the cell in anaphase the chromosomes separate and begin to be pulled to the opposite ends of the cell on these spindle fibers and then with telophase this is at the end of anaphase and you find effectively that those two cells start to separate to new cell membranes are formed and you end up with two daughter cells so I'm trying to show these separating but I'm not doing a very good job so your summary for telophase and membrane forms around each set of chromosomes and you obviously find those chromosomes in the nucleus a new nuclei are formed tiny side point cytokinesis this is when our new cells which are diploid because they contain two sets of chromosomes are separated by new cell membrane so what is gross and there's quite a few little definitions you need to learn so first of all the obvious one it's an increase in size of a particular organism it can be an increase in the number of cells an increase in the size of those cells so we go from a small cell to a big cell in the previous we go from two cells to four cells and then lastly how can you measure this growth where you can measure it by comparing the new mass or the new length I'm gonna talk about stem cells and differentiation now remember a stem cell is a cell which is capable of becoming any other type of cell so they're not specialized and that's why stem cell research is so important now because if you can harness this dancer and get it to produce a hair cell and I sell a skin cell as needed then you'd have a very powerful tool now in animal cells become specialized at a very early stage of their development so when their embryo for example and it's very difficult you can't actually get adult started to become any other type of cell that's a different animal cells because they have stem cells which can constantly differentiate throughout their lives and that's great for the plant because at any one point these cells can become any type of plant cell that the plant requires these growing areas where mitosis occurs in the plant are found in many stems which you find in the shoots and root tips so what are Mary stands well first of all they're group of cells and crucially they're found in plants at the end of shoots and roots and the purpose of Mary stems is that they allow plants to grow continually throughout their life and this growth is obviously due to a type of cell division which we've already mat which is mitosis and the cells either grow in number or they differentiate and become other cell types depending on the need of the plant and this bit here is key the fact that the meristems can differentiate into any other type of cell found in a plant because this isn't really true for us humans or other animals ourselves tend to have their own function unless their particular stem cells so a bone cell will always when mitosis occurs will become a bone cell the same with a skin cell cheek cell etc you so the brain I'll try and find you a good picture or brain because I honestly cannot draw to save my life but here's a very rough picture and let's give the brain some very basic labels so the top part of the brain the bit that looks like a brain is known as the cerebral cortex this bit down here looks a bit like a cabbage in some diagrams is the cerebellum and then underneath here you have the medulla and the brainstem in terms of adding a bit more detail than so I've already said cerebral cortex is the bit which looks mostly like your brain or how you imagine your brain to be so we're going to call this the main part of the brain it's divided into two hemispheres so half spheres and in terms of its function it's all to do with our emotions our memory what makes this asks our personality our behaviors in terms of the cerebellum now this is all to do with our balance maintaining our posture so if we have anything wrong with our cerebellum we will struggle to stay on our feet and now lastly the medulla or the medulla oblongata for giving it its full name this is really the control center of the brain so it controls everything that keeps you alive so it controls your breathing rate and your heart rates so the speed at which both of these things happen and lastly your reflexes so how can we actually look at our brains look at its activity well the most obvious way is through surgery and electrodes are used to stimulate the brain we can also do a number of different types of scan which we need to look at in more detail in terms of the advantage of using scans versus surgery to examine the brain first of all you get a more in-depth picture of the brain you have very little risk of damage to the brain so how can the health of our brain be determined while there are several different ways firstly using brain surgery and here electrodes are used to explore the function of various parts of the brain see you electrically stimulate parts of the brain you keep the person conscious because there are no pain receptors within the brain and you ask them how they're feeling so for example if you stimulate a portion of the brain that causes them to feel hungry then you can be pretty much sure that the portion you're looking at is to do with feelings of hunger but simply put electrodes are used to explore function well then secondly you've got a wide variety of scans so let's start with a CT scan a CT scan uses x-rays movies pass around the body x-ray detectors measure the absorption of the x-rays and then a computer builds an image of the structures found within the brain a PET scan is slightly different this time it shows the brains activity and in this case radioactive glucose is injected into the person an active cells these are most likely to be cancerous cells absorb this radioactive glucose these cells then produce gamma rays which can be detected and in this way the cancer can be located you now we're going to talk about nerve cells and I'll try and add a picture of a nerve cell because they have a very unique shape now first of all they have lots of dendrites and that allows them to make lots of connections with other cells they have a very long axon which is the central kind of actual nerve that forms the length of the neuron and what that does is that it carries the nerve impulse from one place to another because they're very active cells obviously they need lots of energy so you'll find that they have lots of mitochondria to produce that energy and respiration and lastly the nerve endings have special sign apses which it gaps where a chemical diffuses across in order to convert that electrical impulse into a chemical one then let's have a look at this simple diagram of a sense we knew every one now and the bit I'm really interested relates to here which is the axon now surrounding the accident you have what's called a myelin sheath and this is a fatty substance which acts to insulate the axon why does it need to insulate the axon well it's to increase the speed of the electrical impulse transmission so we're going to take the nervous system in greater detail now so let's first of all look at what a stimulus is so that's the change in the environment and obviously that causes the response to the nervous system brings about do be aware of what the central nervous system is that consists of both the brain and the spinal cord let's go through all the steps involved in a regular nervous response one which does not involve a reflex action so I'm going to use picking up a book as an example so first of all we need to list the stimulus which is seeing or viewing the book this is picked up by receptors and these receptors will be in your eyes or proto receptors on your retina they'll send electrical impulses along your sense you know around to your central nervous system electrical impulses then pass along your motor neuron to your effector and this will be muscles or blondes and if this particular case which will contract to pick up your book remember an effect is either a muscle or gland so a muscle responds by contracting the gland responds by secreting hormones don't forget the wall of the signup service signups is the gap between two neurons and this is where a neurotransmitter is released to the neurotransmitter diffuses across that synaptic gap the synaptic cleft and binds the post synaptic membrane so your electrical impulse is changed to a chemical or a neurotransmitter and then change back to an electrical impulse at a synapse looking-out reflex actions remember these faster and they are involuntary so they do not involve a conscious part of your brain and it tends to be in response to something painful so taking putting your hand in the oven and accidentally touching one of the shelves which is hot this would trigger a reflex action so stimulus this time would be the high temperature from the oven train your receptors would be on your fingers which would receive that information about it being too hot electrical impulses would then flow again flow along your sensory neuron to your meal a neuron this time so we're not involved in the conscious part of our brains the electrical impulse passes along the motion over onto your effector which would be a muscle in your finger which contracts to remove your hand or your finger away from that heat source now central nervous system is made up of both the brain and the spinal cord and we've looked in some detail at the brain now we need to look at the spinal cord now this travels down the length of your back it's held in position and protected by the spine which is the bony cage that protects it now if you have damaged your spinal cord clearly electrical impulses won't be able to reach to the bottom part of your body so you end up with a loss of feeling in your legs if you have damage higher up so near your neck area then you're going to lose that sense of feeling all the way down your body so you're going to end up with loss of use of both your arms and legs and we call this quadriplegia so what sort of treatment options exist in order to repair damage to the spinal cord now unfortunately we can't use stem cells to treat spinal cord damage and the reason being is that adult stem cells are unable to specialize or differentiate into other cell types so regardless of the fact we need new spinal cord cells for example we don't have adult stem cells which exists that can do this for us so let's just say and B we're unable to use adult stem cells to repair the spinal cord because adult stem cells can't differentiate into any other two cell types so watch human options actually exist well you could use if you can't use adult stem cells you can use embryonic stem cells because remember in embryos their stem cells can differentiate into any other cell type the only problem with this is ethical issues concerning the fact that you need to use embryos so that is aborted or miscarried fetuses so clearly we have an ethical issue here but theoretically they could be used and secondly electrical stimulation now looking at treating brain tumors here you can use a combination of radiotherapy and chemotherapy radiotherapy is when you use x-rays directed at the cancer to destroy the cells with chemotherapy you're using chemicals hence chemo and these chemicals or drugs which kill the cells but whichever way you use you want to minimize the amount of damage you do to the healthy cells so you want to make sure those x-rays really only effects the cancerous cells and the same with the drugs you don't want them going off and damaging healthy cells cuz that's why people feel really sick on chemotherapy there are several risks associated with treating brain tumors and not just to choose to the things I've just talked about in terms of damage to healthy cells you've got some major issues with the blood-brain barrier which as the name suggests is the separation between the blood and the rest of the brain and these drugs can readily cross the blood-brain barrier and can cause effects far wider reaching and than just the brain right we're going to look now at the eye you need to know lots about this it's a very important sense organ so I'm going to start by running through its various structures and their roles so first of all light enters the eye and it hits the cornea so the corneas role is to refract the light to bend that light as it enters the eye the light then has to pass through the pupil so the pupils role is simply to allow light into the eye the size of the pupil however is controlled by the iris and that is the colorful part of your eye mine's brown other pupils are green or blue and the iris has circular and radial muscles which will actually help it control the size of people we'll go into that in slightly more detail further wrong so now the light has entered the eye it now hits the lens the lenses role is to refract that light further in order to focus it on the retina the retina contains photoreceptors these are cells which are sensitive to light and they are called rods and cones rods are sensitive in very dim light and cones are sensitive to color then we have the optic nerve and that converts those light signals into electrical impulses which can be carried to the brain where they can be computed the white bit of your eye is the sclera and that just forms the tough outer casing if you've ever done sector than eye you'll notice it's full of some black inky stuff that is the choroid layer and that role is to prevent like batting around within your eye then we have a blind spot the blind spot is simply the place on the back of the eye where the optic nerve leaves the eye because clearly there can't be any photoreceptors when you have the optic nerve the fovea is a place that is very concentrated with cones so it's very good for seeing color we need to look a bit more now at the lens so I've already told you that lens the lens focuses light onto the retina it does this by a process of accommodation so accommodation is all about focusing light from different distances away so that an image can be formed on the retina so let's look at what happens when we're looking at an object far away so when it's far away it's going to because the light is going to be coming into your eyes fairly parallel which means it doesn't need refracting very much therefore the lens needs to be thin in order to do this the ciliary muscles relax and the suspensory ligaments are taught and this means you have a very nice thin lens so it doesn't refract the light too much looking at an object really close to us now the light rays are going to be coming in at far greater angle therefore the lens needs to do far more work in order to focus light onto the retina in order to do this the lens needs to be fat so in this case our cinema muscles contract and our suspensory ligaments slacken off meaning that our lens is nice and fat so that's the way in which we focus on light at different distances away we now need to look at the pupil reflex so the pupil changes its diameter dependent on light levels so if there's lots of light that the people needs to be narrower and that's to prevent damage to the retina because too much light entering the eye will damage the retina if we're in a dim or dark room that pupil obviously needs to be nice and wide in order to allow as much light into the eye as possible we can use this response as an example of a reflex action so previously I told you all the steps involved in a reflex action and we're just going to use those steps but we're going to apply them specifically to this example so I'm going to use an example which is that we have walked into a very bright room so the stimulus will be lots of light the receptor will be the rods and cones on your retina then the sensory neuron will pass along the optic nerve to the brain and there will be a relay neuron then we have a motor neuron which is also passing along the optic nerve and it will end in an effector and in this situation the affair is the muscles which you find in your iris so your circular and radial muscles and you'll find that your circular muscles will contract and your radial muscles will relax and that will act an arrow or constrict the pupil so now let's look at why some people need to wear glasses and it's all to do with how the Rays enter your eye and where they end up now the whole point is they're supposed to meet here which is on the retina but in this case of this person you can see that the Rays meet far too early so the Rays converge too early converge means meet and so what's wrong with this person's eye well their eyeball could be too long as you can see there's all this extra eyeball here if it was a bit shorter if you bought the eyeball into here then there wouldn't be a problem or it could be a matter to do with the lens the lens could be too strong so remember the role of the lens is to refract the light and if the lens is doing that too well it will do it too soon as is the case here and this person therefore is short-sighted which means they can't see distant objects in fact that's exactly what I have in order to rectify this you can see the source of lens we've got here it's a concave lens which causes the Rays to spread out here and so that when the lens does its job the Rays are brought sharply into focus on the retina rays now converge on the retina having a look at a sight if an issue this usually affects older people it's why you need reading glasses because you can't see objects close to so these people are long cited cut so can't see objects close to or nearby in this case you can see that the rays converge behind the eyeball or behind the retina so why could that be well it could be that the eyeball is too short so my psyche you need the eyeball to come all the way back here but that doesn't tend to usually be the problem it's usually that the lens is too weak because over time the lens weakens and can't refract the light so well and in this case you need what's called a convex or converging lens and as the name suggests it causes the Rays to come together exactly where they need to be on the retina so look at the different types of lenses we have the concave lens helps to diverge the Rays bring them out the convex lens helps to bring the Rays in so in terms of correcting shortsightedness and long so Janice obviously we can see here you use lenses and glasses or contact lenses the second thing you can do is laser eye surgery and how that works is it kind of shaves portions off your cornea here because if you have a look the cornea is where the light first is refracted so if you can actually shave the cornea then you can help to fix eye problems here let's just touch on cataracts now and we might as well use these diagrams here so it's when the lens so the bit that I'm highlighting the lens becomes cloudy with cataracts and obviously if it's cloudy you're really going to pick up a very poor image and the reason it becomes cloudy is due to protein and the way in which you fix cataracts is by replacing the lens with a plastic lens let's look at mitosis and meiosis now so remember they're both types of cell division but they're used for making very different things so meiosis is used to make gametes so that means it's used to make sperm and egg mitosis is a completely different type of cell division you need to learn that it's used in cloning asexual reproduction and the growth and repair of cells so for example if you damaged yourself you cut yourself it will be mitotic cell division which replaces those cells if you're carrying out asexual reproduction so something like a strawberry rather producing baby strawberry plants that will involve mitosis the reason being is that it creates genetically identical offspring let's look for the differences between mitosis and meiosis I always do this as a table because it makes allows me to make a direct comparison so look at the number of cell divisions first of all that will be one cell division in mitosis two cell divisions in meiosis the number of daughter cells now so that's the number of cells produced once this cell division has taken place in mitosis you're looking at two daughter cells in meiosis you're looking at four daughter cells I've already touched on the sorts of cells that are produced bit just to recap mitosis produces genetically identical daughter cells meiosis produces genetically varied daughter cells which makes sense if we're using mitosis in cloning that's genetically identical for using meiosis in making gametes that make sense that we want us balance lag to all be different to each other and do notice that the gametes will contain a haploid number of chromosomes whereas the daughter cells produced by mitosis will contain a diploid number don't forget that haploid means containing one set of chromosomes so in humans such as 23 diploid means containing two sets of chromosomes in humans that is 46 looking at species now so what is the definition of a species well it's individuals which can be produced to produce fertile offspring and that's key it's all very well having a horse and a donkey and they mate then they produce an offspring which we call a mule but then we all is sterile it cannot reproduce so that's the crucial thing about members of the same species they can be produced together to produce fertile offspring no hay all soggy what's it freakazoo your soul soggy is it worse out that super soggy so how is variation within a species brought about because we know the human race isn't full of billions of people that all look the same that is brought about by a combination of things first of all genetics and secondly environmental factors so two identical twins we gotta stir the fact they have the same genes if you move them to the opposite parts of the world it's very likely they'll have different heights different masses different slightly different skin color and that's due to the environment they experience that could be lots of Sun one of them could eat more one of them could do less exercise are you to money you power monkey this makes a change what is the mutation it's a very random change to the genetic material of an organism so a mutation can be brought about by a number of things things like ionizing radiation exposure to UV light x-ray exposure and various mutagens which just chemicals which cause mutations and you find those and things like cigarette smoke now the crucial thing with mutations is what they do is they alter the DNA of an organism we've already looked at protein synthesis so if you think about it if you alter the DNA of an organism what that will do is it potentially alters the sequence in which amino acids are assembled and therefore it can alter the end product so the end protein which is produced proteins are responsible for phenotypes so our physical appearance so mutation can therefore cause an alteration in our phenotypes now not all mutations cause this alteration because sometimes a mutation occurs where the DNA although it has changed it doesn't actually alter the order in which the amino acids are assembled so you end up with the same protein here let's look at continuous and discontinuous variation now and hopefully these met these few words in maths we already have a clue a little bit about what we mean now continuous is all to do with having a range of values and it results in a range of phenotypes which fall between two extremes so for example your height so taking people in your year they'll have the shortest paths in the year which let's pretend they are hundred twenty centimeters tall the tallest person might be 200 centimeters tall I don't know if I'm making upsetting numbers by the way in the UK for some reason we described the height in terms of deep so I'm five foot four inches which is really silly because we use the metric system for everything else whereas discontinuous variation results in limited phenotypes with no intermediate values and we've already met a really good example which is flood loops you're only one type of blood so you could be a you could be B you could be a B or o we are not a combination of all four the same could be said with something as silly as tongue rolling the general thinking here is that some people can bother tongues some people can't and you can't kind of do it halfway and be aware that this is all to do with genes which you should know from doing the genetic cross you moving on to the protein synthesis partial specification we should start by looking at some key definitions such as genome and that is the entire DNA belonging to an organism so we're focusing on on the nucleus of a cell remember that the role of the nucleus is to control the activities of the cell and it does this because it contains lots of genetic material so within the nucleus we know that there are chromosomes there are 46 chromosomes which is a diploid number because remember they're arranged as 23 pairs remember half the number of chromosomes is known as a haploid number however I digress and everyone's talk about that now so the chromosomes are made up of DNA you need to know the definition of a gene a gene is a section of DNA which codes for particular protein looking more closely at DNA now so we need to first of all know what the structure of DNA is remember it looks like a ladder we call this a double helix which winds itself up it's made up of a sugar phosphate backbone and remember that the sugar here is deoxyribose why because dNA stands for deoxyribonucleic acid so assuming it is deoxyribose there's a phosphate and sugar backbone and then linking the two backbones the rungs of the ladder are bases and remember the names of these bases adenine thymine guanine and cytosine looking more in depth at the neck various names involved nucleotide a nucleotide is simply just three units made up of a deoxyribose sugar a phosphate and lastly a base so it could be either one of those bases I've just mentioned say adenine thymine cytosine or GU anine do sorry but I sounds wait now you're saying it mustn't ever even financing very long my father you teacher said Q&E and i don't know how to say it any other way finally he says guanine mmm so we all need to now look at complementary base pairing that's when the various bases pair up in a very specific way try and remember the show of the letters match so Guin in awanee always pairs with cytosine if they're both kearney in terms of the G and the C adenine and thymine always pair up and that's because they're the straight letters so you use that to help you remember looking at the difference to denominator DNA the main difference here is the sugar involved so iodine has ribose sugar as opposed to DNA's with deoxyribose and lastly there's a change in base there is no thymine in RNA you've got to learn that this time it's uracil so adenine pairs with uracil in RNA and cytosine and guanine still pair up RNA is single-stranded compared with DNA's double strands so we don't see a ladder with our neighbor to see one side of the ladder effectively let's move on to looking what a codon an anticodon is so a codon is just a fancy way of describing three bases which are found on the mRNA molecule and they correspond to a single amino acid and anticodon is the three complementary bases which you find on tRNA and they pair up with the codon so although I've touched on mRNA tRNA codons and palin's we try to understand why we even mentioning these words hopefully you'll know this from your school classes after all this is a revision venire but now I'm going to go into great detail about protein synthesis so remember protein synthesis is all about making new proteins it's about sorting out the arrangement the sequence of amino acids so they can actually produce a particular protein and we're going to talk about how those amino acids line themselves up in the correct order aka protein synthesis so there are two main stages transcription and translation and the first stage is transcription so you need to go into it up now so I cap so with so with transcription first of all the DNA needs to unwind to expose a single strand so we're going to expose those bases on the DNA there are bases floating around inside the nucleus and RNA bases and they come along and they pair up with those exposed to any bases start forming that mRNA molecule and it's a single strand no to think that yourself has replaced by me so we call this complementary base pairing and a codon is simply three of those mRNA bases in a line so we have created our mRNA or messenger RNA because it carries the message from the DNA and now needs to leave the nucleus so it leaves by a nuclear pore and attaches itself to a ribosome which we find within the cytoplasm hence the summary definition of ribosomes role is that it carries our protein synthesis so the mRNA attaches to a ribosome and this is where translation begins so there are tip tRNA molecules within the cytoplasm and they have complimentary anticodons so they'll have the three bases which complimentary base pair up with the mRNA exposed bases and on the other end of that T tRNA molecule will be an amino acid and effectively the tRNA brings the amino acid to the mRNA the codon will much help with the anticodon and we have our first amino acid in place then the next few bases on the mRNA will be red and a different tRNA molecule bring probably a different amino acid along because if there are different bases it will correspond to a different amino acid so the second amino acid has been brought and they attach to each other using a peptide bond so that is the start of our protein chain and it keeps going and keeps going and eventually a stop codon will be reached and that's just three specific bases which correspond to no amino acid whatsoever and that will signal the end of that growing protein chain know the definition of a mutation that's a random change in the DNA of an organism so effectively those bases we know that they occur in a certain order within DNA a mutation will cause have changed those bases so first of all it could just be a straight substitution it could be a deletion so whole base could just be taken out and you find where the deletion is that effectively all those bases move along one place so you'll end up with tokens amino acids being produced this quite likely that you'll end up with huge disruption in the protein made there might be an inversion which is when the two sides two bases in the DNA swap over there could be duplication when it basically simply copies so there could be two Adaline's in a row for example and again that will most likely cause a change in the amino acid which is brought along to the ribosome you we're going to talk about genetics now so we need to know the definitions of lots of very key important terms and then I'm going to show you how to do punnett squares and pedigree analysis so let's start by looking what a gene is a gene is a section of DNA which codes for a particular protein now there are different genes which control different traits so for example eye color now different forms of the same gene we call alleles so you must learn that definition so if we take I color for example different alleles for eye color could be blue or brown you must now know the meaning of the word genotype the genotype is the annuals an organism has so for example when we're talking about blue eyes it's too small bees if we're talking about brown eyes it could be Big B little B so when you ask for genotype you must provide letters the phenotype is different this is the physical appearance of a particular trait so if you're asked for the phenotype of this eye color the answer here is blue so the genotype would be little B little B the phenotype would be blue eyes so be very aware of that distinction next up we need to know the meanings of homozygous and heterozygous homo means same so it means having two of the same alleles whether that's two big bees or two little bees it doesn't matter as long as they have the same case so they both need to be apart or they've both needs to be lowercase and that is the meaning of the word homozygous heterozygous means different so that means containing different alleles so in the case of eye color that would be a big B and a little B now a dominant trait requires simply the presence of one allele for it to exhibit itself in an individual so brown is an example of a dominant trait because you can have two big bees or two a big B and little B and the trait will still appear recessive requires the absence of the dominant allele so a recessive trait could be blue eyes because you need two little E's for example a blue-eyed mother and heterozygous Barnard father decide to try for children what is the probability that the children will have blue eyes so let's talk about what we have here first of all blue eyes remember blue is a recessive trait which means that her genotype must be small B small B we've been told that the father is brown-eyed which means he could be Big B small B or Big B Big B but the fact that his heterozygous tells us that he must be Big B small base and not Big B Big B so I'll show you how to lay out your answer this is the method you should always use to start by writing mother and father at the top and we know how much I love tables so you're going to write in your table between a type genotype and lastly gametes remember these are sperm and eggs so the phenotype this is the physical appearance we can see from the description that the mother has blue eyes and the father has brown eyes the genotype so these are the aliens for each parent has already written these out so small B small B Big B little B the gametes just spit these up because this is saying what the eggs and sperm will be so just write out what you vote on the genotype layer but put circles and run them to show that they're Gammy's because here the sperm and the mothers are eggs and now we need to do the punnett square so mother father I don't know why my iPad sometimes undoes what I've done already so she's small B small B he's big B little B let's cross them so it's big B small B Big B small B small B small B and therefore both of these will have blue eyes exposed to speeds will have brown eyes so as a percentage like it here it's 50% will have blue eyes and 50% will have brown eyes cystic fibrosis is a recessive disease a caring mother and a caring father decide to try for children what is the probability that their child will have cystic fibrosis so it's recessive which means to have the disease you need this genotype small C small C it doesn't matter what lesser you use to assign by the way but I'm using C here with is assisting fibrosis a carrier mother and a carrier father that automatically tells me that this is their genotype and you must learn that they're effectively heterozygous if they are carriers so worked out their genotypes so we're ready to do the genetic cross by writing mother and father at the top again you know type genotype and gametes in the table the phenotype is that they are both carriers so their genotype we know is heterozygous oh it's Big C small C this means that half of her eggs will be Big C half of them will be small C I'm the same with the sponge make sure you really show difference in the size of your letters here and now it's time to do the punnett square so this child is Big C Big C so they'll be healthy this child is Big C small C so they'll be carriers but they're still we have the same for this one and lastly this child here will have cystic fibrosis so they have a 25% chance of having a child with CF so let's now look at how we inherit our sex remember this is all to do with chromosomes so women have two x's and men have an x and a y and that is the pair of chromosomes which dictate your sex so that's initially have a quick look as to why 50% of the population approximately 50 percent are male 50 percent are female so let's start by writing mum and dad right phenotype so what do they look like what the ones obviously female father is male the genotype you're going to use so sex chromosome test it'll be exact he'll be XY the gametes so obviously at the eggs will be X fun where you can either be female or male sperm and then if we look at the cross across the mum up here your dad down here and you see this situation which shows 50% are attracted a female 50% are XY to their male although we know based on the evidence that the man spam determines the sex of their child and the chromosome so that X X or the XY contain lots of genes associated with the development of sex organs you might not know that they have lots of other roles which might not be to do with sex at all and they can a code for characteristics which are completely unrelated to sex so the sex chromosomes also carries G's that's home to characteristics unrelated is that and a very famous example of this is colorblindness that's whether you can see in full color or not and because it's carried on the X chromosome so a sex chromosome we say weirdly that colorblindness is sex linked let's look more closely at colorblindness as a sax link characteristics and a very well-known one is red-green color blindness which is when you can't tell the difference between the color red and the color green and it's carried on the X chromosome only and when we do our crosses just so you know in order to have color blindness you need to have a small C so if you're a guy to have color blindness you need to have a X small see the Y you're not going to have a C on it because remember I already told you that it's code by the x percent only as a female to have color blindness you need to have two small C's if you have a big sea under little C then you're just going to be a carrier if you have two deputies then you're going to be completely normal so let's do a question to try and make this a bit more straightforward so we're going to cross a carrier woman and normal man so using our normal way of writing out our crosses so we've got a woman and a man the phenotype first of all well we know the woman is a carrier the man is normal the genotype as you look at my crosses up here she needs to have a small seat and a big stay in order to be a carrier and he's normal which means he must have a big feet attached to the X and remember the Y chromosome doesn't carry any genes for colour blindness so we leave that as it is so the gametes the woman's eggs will either be big seeds or small soon and the man's sperm will either be big seed or just a Y which will obviously code for a male sperm so now let's do the cross so this so this first offspring will be just a normal offspring the second offspring will be a carrier of colorblindness there's male offspring will be normal and this final male offspring will have color blindness so let's write them out 25 percent of the offspring will be male and have color blindness and that's due to a combination of values which is X small C Y 25% will be male and I'll be normal because they have X 50 y 25% will be female and they'll be normal and 25% will be female and they'll be carriers with the Big C small C codominance is when both alleles are expressed in an individual the example here we use is red snapdragons so we've already looked at codominance but they're very interested in how it works from a blood creep point of view so there are four different blood groups they are and B a B and O so you need to learn those you also need to learn the genotypes which represent each blood group and form of codominance point of you remember that we have got to write them in this very specific way which is we choose the base letter and then we have a superscript showing the ally or for particular blood group and that will be more clear once I start drawing them out so for eggs the potential genotypes are ia ia or IA i o4 b you're looking at IB IB IB IO for a B you're looking at ia and I deeds and for owed you need I owe I owe to make sure your players are that's an all and now let's have a look at an example so you can actually see it in practice so let's look at an example to make it nice and straightforward so we're drawing a genetic diagram to explain the inheritance of blood group in the Smith family mr. Smith has the genotype ia IB and mr. Smith has the genotype aiyyo aiyyo so using my method from before we're going to lay it out as a table so mr. Smith mr. Smith start with our phenotype so what blood groups do they have well according to my previous slide ia IB you will obviously be blood group a B mr. Smith mrs. Smith has ioio which means her blood group is oh so what are their genotypes for happily that's been given to us in the questions that's just IA ID for mr. Smith's aiyyo aiyyo for mrs. Smith so the gametes we just need to separate those alleles and draw circles around them to show that this is the potential alleles for his sperm and her eggs will all be IO now let's do the punnett square and just cross them and then from the previous slide we know what each of the child's phenotype will be so i IA that's 50% of the offspring and i'll have flood group a and ioi b is the other 50% of potential offspring and i'll have blood grouping so now we need to look at pedigree diagrams and the best way to do this is by showing you an example always use this approach and do notice these are supposed to be really difficult so don't worry too much if you're planning it too much question 3 familial hypercholesterolemia fh is an inherited condition caused by a dominant allele that is key people with the condition have high levels of cholesterol in the blood increasing the risk of dying from blocked arteries the diagram shows the pattern of inheritance in several generations of a family with familial hypercholesterolemia so do natives with a pedigree diagram that the squares are always the men in the family you'll know this from the key the circles always represent females and in this case from the key we can see that the gray shaded boxes are sufferers of FH whilst the white boxes or circles are non sufferers so person a is heterozygous for FH use this information to complete the table so let's start by labeling the genotype of F of person a and we are going to use the letter D I mean doesn't matter what letter years I will now use the letter D because you can easily see the difference between a capital D and a small D so labeling their genotype this is what they look like so big D small D so what is the question actually asking how many people have the genotype which is homozygous recessive so homozygous recessive homozygous meaning the same case recessive meaning lowercase which is why we're looking for small D small D here homozygous dominant homozygous meaning the same dominant meaning that they're both capital so that's what we're looking for now we're going to work out what the pedigree diagram tells us first of all I'm going to look at all the people without FH so all the people that are either white circles or white squares because they don't have the disease i know therefore that they are small D small D so I can just label all of their genotypes straight away and now we need to count them to work out the number of people with the genotype homozygous recessive and once I've done that I can see that it is 11 now we're getting slightly more difficult by looking for the Big D Big D so homozygous dominant so we need to infer the from the pedigree analysis first of all look at woman seen so she got hurt genotype from parents a and B now B is homozygous recessive which means they must have passed on a small D she has the disease which means she must have a big D so this is her genotype e has the same issue but they're a man so they're going to be Big D small D passing G inherited a small lowercase allele from D they have the disease which is why they're capitalized and the same goes for person J and then looking at NOP for they inherited a small D from their mother they have the disease which is why they have a big deal so actually looking for people with Big D Big D the answer here is zero person G and H have three children all who all of whom have FH what is the probability of GH having three children who all have FH this is a crazy amount of work for one mark because the only way I can see of doing this is to draw a Punnett square so we're going to do a Punnett square for G and H using my layout I already described so we're looking at the phenotype genotype and gametes from the key we can see the person G has fh h is therefore healthy from the key we've already labeled their genotypes so you can just copy that directly across and then separate these out to see the gametes now just simply do across and it's these two here that will have F H now what is 50% as a probability we're at 0.5 and the question asks the probability of all three children having FH so remember when we're talking about probability we have to multiply together our probabilities pop that into your calculator and you'll get a value which is 0.125 very short topic now on evolution and natural selection so firstly a definition for evolution it states that many organisms which are alive today and many more which are now extinct first evolved from very simple life forms that first evolved over 3.2 billion years ago so that's basically saying that evolution states that we all evolved from small life forms like bacteria which became multicellular which became more more complicated they became reptiles that became Birds and then they became mammals and then we came about so that's really what evolution is dating natural selection links very nicely with this remember this is Charles Darwin's theory now he stated and I do just want you to learn this as a 5-mile cancer off by heart he stated that there is variation within a species due to mutation which is what I've just discussed so within a species that is variety this means that some individuals within the species are more likely to survive because they are better adapted because they're surviving they're likely to reproduce so produce offspring and those offspring will inherit those favorable genes so before you know it you have many generations that go past and they all inherited this favorable gene making them more likely to survive and I'm now going to bring up that power for answer for you natural selection can be seen pretty much everywhere on earth including bacteria so we're just going to describe how but to maybe become antibiotic resistant and it does link to natural selection so what happens is you have a colony of bacteria you give them antibiotic and due to mutations some of those bacteria are stronger they are resistant that means they are not killed by the antibiotic so what happens is all the other bacteria killed leaving behind these very strong antibiotic resistant bacteria they soon that became before you know you've got a colony of bacteria which is no longer suitable using antibiotics and that's why I'm so scared about antibiotic resistance and what it means for our future medicine so how do stone tools provide evidence for human evolution well let's first of all look at the evidence of human-like species using stone tools and that actually occurred 3.3 million years ago so an seriously long time ago and they noticed that the more recent roles that showed much greater sophistication so basically tools became more sophisticated over time and how do we know how old these things are after all we want around 3.3 million years ago this is where physics comes in and particularly radioactivity because remember we can do radioactive dating looking at the Penta dr. Lim now so Penta dr. so pent meaning like Pentagon's so five that tall is to do with how many fingers you have so that's five fingered limb and really we like to use the anatomy of the pentacle limb to provide evidence for evolution because actually you find the same limb anatomy so the same basic limb structure between all kinds of animals including turtles dolphins bats and humans and I know you're thinking but hang on we look completely different from a dolphin however the point is we think that we all evolved from the same common ancestor and then the various branches came off and the Penta doctor limb ended up evolving into a completely different structure because it needed to serve a different purpose so obviously for dolphins it needed to become a fin to enable them to swim whereas for bats that five fingered limb needed to become wings to help them to fly and then obviously as humans we needed them to become hands to help us pick up stuff and that really sets us apart from other creatures so the suggestion is that we came from a common ancestor you now we know that millions and millions of different creatures exist so how do you know if one creature found is a new species or if it already exists but you just haven't clapped eyes on it yeah so we use a classification system in order to help us name these things and one of the original classification system was Linnaeus's I don't know if I'm pronouncing his name right and he basically said that there were two kingdoms the animal and plant kingdom and that these were divided into smaller and smaller groups based on their physical characteristics however the issue is with his particular classification system is based on putting animals into groups based on their physical characteristics you'd end up putting bats and Lady birds or flies in the same group and the difficulty here is if you think about a bat wing versus a bee's wing or fly's wing it is so unbelievably different and that's because their evolution of their wing came about by completely different processes so it wouldn't be right to place them in the same group plus he only includes animal implants and we know there are lots of other type of organisms exist such as fungi protists prokaryotes etc so really his system wasn't big enough so the traditional classification systems so not ones based on the binomial method we use now was based on evolutionary similarities and it grouped organisms based on their morphology and Anatomy so effectively the bones which make them up a more accurate way of classifying these organisms is to look at greater detail so actually look at their structures and that means looking at the sequence of bases in their DNA and now how these sequence of bases determine which amino acids form which proteins so that's a more accurate way of determining how we should group organisms more similar sequences of DNA so more similar amino acids and proteins are more likely to be closely related if we're going to use the correct nomenclature when we're talking about naming things we can talk about five kingdoms and that consists of plants animals protists bacteria and fungi now selective breeding so remember this is when humans use animals or plants with desired characteristics they force them to breed and then they repeat this process over many generations before you know it you have animals with desired characteristics so if we're looking at animals let's for example look at the dairy industry so dairy cows clearly a good animal here will produce a lot of milk so at humans to make sure you point out that it's humans they select a dairy cow that produces a high yield of milk they make home with a ball it's quite hard to determine the bull cuz obviously they don't produce milk but they'll make her with a ball and then her carbs are likely to produce more milk so female calves because of their high yield mother then you take those cards and you keep repeating the process until you have lots of calves and lots of cows that produce lots of milk and you can do the same with plants so you can selectively breed plants to a particular color so you pick flowers that are a particular color you force them to cross pollinate and then before you know you've got a load of plants with your desired characteristics such as petal color genetic engineering now this is quite a complicated topic it is chock-a-block full of key scientific words but if you learn them off by heart you should be fine so remember we chanted engineer things like insulin so insulin is a hormone produced by our pancreas and it's responsible for lowering our blood sugar levels after we've eaten and for type 1 diabetics they find that they don't produce insulin so they really struggle to maintain their blood sugar levels which is where genetic engineering comes in because in the olden days they used to obtain Pig insulin so used to chop into pigs remove the insulin I'm not going to have major ethical issues with this but obviously the insulin wasn't particularly fit for purpose because it came from pigs so it was important that we found a way of producing insulin from humans and so that's where genetic engineering came in and when we talk about genetic engineering we're talking about using bacterial cells because bacterial cells contains small wings of genetic information called plasmids which we can manipulate so that you can insert the insulin gene and force the bacteria to produce lots of insulin so let's go into great detail how that is done so we obtain the bacterial cell and we cut open the plasmid using a restriction enzyme which acts as a pair of biological scissors then we use a restriction answer to cut the insulin gene away from the rest of the cell and we insert that insulin gene into that bacterial plasmid using a ligase enzyme and we stick it together and that's why we say how sticky ends once you've done that we're ready to put the bacterial cell into a fermenter and it's been done many many times and then I would imagine a fermenter and you need to provide it with the optimum conditions to the right temperature the right pH the optimum amount of oxygen and nutrients etc and before you know it you're back to has made huge amounts of insulin don't forget a few key words here concerning genetic engineering once that placement has a different gene inserted into it we call it a recombinant plasmid which means it's been be combined so it's been changed and don't forget also that the bacterial cell the plasmid is acting as a vector which means it transports biological material from one place to another we can also genetically modify plants so that they can have desired characteristics this could include being frost resistant so that stops them dying when frost hits in winter it could be to extend their shelf life to stop them going off so that they have a longer shelf life and a more fit for human consumption after many days you might actually want to make plants resistant to weed killers this sounds really strange because why would you want to make a plant resistant to weed killer but think about it a farmer implies that weed killer by the way the best name for weed killer is herbicide side meaning kill herb meaning to your plants so the farmer applies the herbicide he or she wants to kill the weed however some of it will inevitably fall on the plant that they're trying to grow and obviously you don't want that to happen because it will actually kill the plant you're trying to grow so if you can make that crop plant resistant to herbicide then that's great because you applied that herbicide or weed killer it kills the weeds and your actual plant that you're after stays alive and continues to grow you can also genetically modify plants so that they can actually have health benefits then one of the most famous examples of this is Golden Rice so when poor countries grow lots of rice unfortunately rice doesn't have a huge amount of nutritional value so what you can do is genetically modify it so that it contains vitamin A and therefore when people eat that rice think they get a huge amount of wisdom in a in their diet and that stops um getting night blindness this is something you should remember from the balanced diet topic of the specification so golden rice is an excellent example where genetic modification has been used really well and then the most strange example of Jensen modification is when we talk about tobacco plants and these have been modified so they actually produce hepatitis antigens therefore have a potential vaccine against hepatitis so this is like crazy science but just remember that tobacco plants may be modified to produce hepatitis vaccines so we've already touched on this we've given lots of examples object modification implants just to reiterate the advantages and and a few more you can have increased salt tolerance you so how does using fertilizers increase crop yield well the addition of fertilizers to the soil replaces leach or lost nitrates and mineral ions from the soil because remember fertilizers are very rich in nitrogen nitrates and those nitrates are used by plants to build proteins what is a pesticide remember it is a chemical which kills past's so anything which feeds off plants will be counted as it passed having pests obviously reduces the damage to the crop and it also helps to increase crop yield looking at how we control pests further remember we can add chemicals so pesticides or we can use biological control which is about using other animals which kill and eat the pests need to look at their various advantages and disadvantages so let's first of all look at the advantages of using pesticides now these are easy to use so they're easy to apply they're effective which means they do a pretty good job of killing the pests and they're readily available issues though there's lots of issues with using pesticides firstly that they have me very expensive that per system which means it takes a while for them to decompose so once you apply them to your soil you've got to be a whether they may hang around for many many years and the problem here is that they can often kill animals which aren't even pass which is really really bad because these are innocent animals getting killed by the pesticides because the pesticide does not discriminate correctly so what happens here is it kills other animals some of these animals get eaten by large animals so we're talking about food chains here and this is called bioaccumulation where the pesticides become stored in these animals and then as this pesticide works itself up the food chain we call this by magnification and the famous case study this is DDT which was used to eradicate malaria and typhoid in the Second World War and there are still areas of the world where DDT is killing huge amounts of and fauna Madison's animals and plants another disadvantage to see how to keep reapplying this pesticide looking at biological control NASA let's name a few examples so like I said before this is using animals to kill paths the most famous of all probably is using lady Birds because lady birds are predators to a friends so they come along and munch on the aphids which would otherwise be destroying things like cabbages so one of the advantages of using lady birds using biological control they tend to be quite specific and kill the pests that you're after secondly they're self-sustaining they tend to reproduce which is great because you don't have to keep reapplying lady Birds intend to grow into new populations which will continue to eat the aphids I'm clearly nubbly non-toxic especially when compared with things like DDT however there are disadvantages they have been known to not just eat the pests that you're after we can go around eating other things so that can be both an advantage and a disadvantage they never fully eradicate the past so there will still be some aphids which survived the purge because the ladybugs don't go eats all of them when you add extra animals to an environment to an ecosystem they can have undesired effects you really know what they're going to do they can have major effects on futures they really disrupt them so you do have to be careful before you decide to apply these animals to your ecosystem and lastly compared with using pesticides it's pretty damn slow waiting for the drugs to go and eat all the aphids whereas when pesticides you tend to find everything gets wiped out immediately now we need to look at the health disease and development of medicines topic and starting with the whose definition of half and w-h-o or who is the World Health Organization so people tend to think that they're the go-to in terms of knowing about these things so what is their definition of health well it's a state of complete physical mental and social well-being and not merely the absence of disease or infirmity so it's not about being like right I haven't got cold I haven't got this I don't have this particular genetic disorder it's talking about both your mental and your physiological health let's look at what physical well-being really means and it means that no disease so an absence of disease it means good diet regular exercise and a low intake of harmful substances so that could be dangerous drugs for example looking at mental well-being really we're looking for happiness and contentment in being who you are and if you have both of these things you have complete health according to WHO what is social well-being that's to do with your relationships with other people so we're going to write relationship with other people is good and that you're comfortable in your surroundings so is their relationship between health and income well lots of people tend to think there is so if we were to draw a really basic graph showing increased income along side increased health you would definitely see a positive correlation obviously this is a very general statement and it's not necessarily true for everyone but as income increases health increases and that's for obvious reasons in the if you have a higher income you have better access to medicines and better diets and places where people tend to have higher income occur in countries which are less prone to natural disaster because natural disaster like earthquakes obviously kill large numbers of people notice that the relationship is what between half and income isn't causative so it's not necessarily true that you have a higher income meaning that you have greater house looking more closely at disease now so what is the disease well it's a disorder of the body which produces specific symptoms and crucially it's not a result of physical injury so if you were to damage your leg having fallen down the stairs that is not an example of a disease now there are different types of disease you need to know about first type is communicable diseases and as the name suggests these can be transferred between people and these tend to be caused by pathogens and remember a pathogen if they ask you is a microorganism which causes disease such as a bacteria or virus now a non communicable disease is one which cannot be passed readily from person to person and it's actually caused by your genetics or lifestyle so if you inherit cystic fibrosis that is a non communicable disease if you get lung cancer due to smoking again a non communicable disease you can't pass on lung cancer by accidentally brushing against someone for example let's touch more on this pathogen definition we've already said what it is but there are other words associated with it that you need to be aware of and one of those is a vector which is actually a mass term as well but in biology it means an organism which carries pathogens so it doesn't actually cause the disease itself it's just a means of transporting a pathogen from one person to another and a good example here is the mosquito so although these are super annoying when they bite you and suck your blood they're not actually responsible for giving you malaria in fact it's the fact that they carry a protic test called Plasmodium and it's obviously an example of a pathogen and that's actually what causes malaria viruses are very different to bacteria and other types of Sall mainly because they're nonliving they simply consist of DNA or RNA surrounded by a protein coat and they need to reproduce inside another living organism many diseases interact and if you're suffering one disease from one disease it can mean that you increase your likelihood of getting another and why is that well that's because your immune system becomes weakened and therefore other pathogens are more able to cause disease when you're suffering from a disease it does tend to mean that your various barriers may become damaged meaning that it's more likely the pathogens will be able to enter for example if you have measles it's a very very bad skin rash in fact it can be fatal for some people now you're likely to scratch because it's itchy and obviously if you scratch your skin you break that barrier meaning that other pathogens can enter your bloodstream and lastly if the disease affects various important organ systems within your body it does mean that other diseases are able to occur for example if you got tuberculosis well that would damage your respiratory system so your lungs and therefore you'd be more likely to get something like bronchitis now we need to look at various types of pathogen and the diseases they cause so let's start with a bacteria called Vibrio chloride and as the name hopefully you can see that that would cause cholera and unfortunately people who suffer from cholera get chronic diarrhea which can actually kill them it's a really terrifying disease and it's a waterborne disease so the bacteria live in infected water supplies looking at another example I've already mentioned this one tuberculosis so I'm going to call the disease here TB is caused by the Mycobacterium tuberculosis T symptoms here you often end up coughing up blood and that's due to lung damage these bacteria make small holes in your lungs the Ebola virus now got a lot of press a few years ago it was killing lots of people in Africa this causes hemorrhaging so bleeding from all kinds of orifices and we call this hemorrhagic fever so hopefully you recognize him that means to do with blood HIV now human immunodeficiency virus which progresses to form the disease aids this destroys the immune system it infects your white blood cells and lastly a protest by the name of Plasmodium which I already mentioned causes the disease malaria and it causes widespread damage to your blood and liver and even your brain sometimes depending on the type you get let's label these various pathogens and talk about how they're actually spread so fabric lore I already said it's mode of transmission is infected water so people drink water containing for Brio chloride they will get cholera Mycobacterium tuberculosis TB maybe you notice from history people got it from accent and coughing on each other which means that it's mode of transmission is that it's airborne Ebola is spread in infected bodily fluids so blood carries it and we know that you get it excess bleeding with Ebola so if you want to send me get some of that infected blood on you that's how you could potentially get Ebola HIV is a sexually transmitted disease so if you have unprotected sex you're more likely to get HIV and we've already said that Plasmodium is spread via the vector mosquitos some more key definitions now so what is a host while it's an organism carrying the pathogen and the disease so if it infects us we'd be the host if it's a plant that houses tobacco mosaic virus than the host here is the plant so we've talked a lot about various types of disease and how they're transmitted but how can we actually prevent them so number one just generally good hygiene washing regularly in order to remove those pathogens from our body to prevent airborne diseases you want to avoid coughing and sneezing on people which is why I find it particularly gross if people accidentally cough or sneeze on you when you're on the tube anyone's been to London and rush-hour you will know what I'm talking about to prevent diseases spread by dirty water you want to treat that water so disinfect the water to kill pathogens diseases such as HIV which is spread through sexual contact you want to wear condoms in order to prevent the spread of HIV and marci if you're trying to prevent a disease which is spread by vectors such as mosquito clearly you want to kill the vector or you want to drain its water supplies where the vector reproduces or you want to cover your beds with nets to stop the mosquitos biting you we've already mentioned how viruses are so very different from a regular animal plant or bacterial cell but how do they actually infect an organism well firstly they have to inject either their DNA or RNA into the host cell next up they need to hijack the living processes of the cell so that the cell starts to do the virus's own bidding as part of this the cell copies the viral DNA and then effectively the cell bursts releasing thousands of copies of the virus which can obviously go on and infect other cells and before you know the virus has spread everywhere and has caused massive damage to pre-existing cells a key definition now which is lysis lysis is simply the total breakdown of a cell this ceases to live linked with what we're saying about how viruses replicate and the meaning of the word lysis is the lytic cycle and this relates to viruses and it's actually the process by which a virus replicates itself and destroys the host cell a second important definition is a phage and this is a virus which particularly infects bacterial cells so pathogens go out of their way to cause disease damage us as humans and other animal hosts and plant hosts so how can plants for example defend themselves against attack and there are two main ways the first one is physical barriers and the second is chemical barriers so let's list some physical barriers firstly the waxy cuticle forms a tough outer casing on the leaves and the stems oak trees have a particularly thick bark and generally the cell wall of the plant remember it's made out of a tough material called cellulose which acts as a protective measure now we need to look at chemical barriers and we're really looking at poisons many plants contains some pretty toxic poisons which can kill insects if they try and eat them and that's why it was really careful back when we were hunters and foragers we had to make sure that we didn't poison ourselves by eating deadly plants such as the foxglove foxglove is very famously poisonous so don't touch those if you see them in woodland but as well as being poisonous a lot of plants contain some very useful chemicals which we can actually use to make drugs used to treat disease and pretty famous ones include aspirin which is actually originally produced from the willow tree and that's used to relieve pain and help to thin the blood if you're prone to having a stroke also helps reduce inflammation slightly more niche is art Mesa Ninh which is used to kill the Plasmodium which we know causes malaria so how can disease actually be detected implants first of all just by looking at them so we observed the symptoms such as if a plant's suffering from tobacco mosaic virus you get a very distinct discoloration of the leaves you can also use home testing kits or you could send off your sample to a laboratory for analysis linked with this is a fairly niche topic which is distribution analysis and this is an analysis of whether damaged or diseased plants are located and you often find that similar symptoms can be caused by a variety of factors such as diseases spread by wind have different distribution than diseases caused by pests or lack of nutrients next topic white blood cells and the immune system so let's first of all discuss how we prevent pathogen entry in the first place so remember our skin acts as a barrier our hydrochloric acid in our stomach helps to destroy pathogens our tears prevent pathogens entering our eyes and also your eyelashes but what happens whilst those pathogens actually enter our body and to our bloodstream clearly we can't stay ill forever and ever and ever so there are mechanisms in place which actually act to remove those pathogens the two mechanisms you need to know about are white blood cells and they are the phagocytes and the lymphocytes so starting with the phagocytes remember that they engulf or ingest pathogens by enclosing them inside a vacuole and then digestive enzymes are secreted which destroy the pathogen the second type of white blood cell is the lymphocyte the lymphocyte is far more complicated and it works by recognizing the antigen on the pathogen it secretes lots of antibodies which destroy that specific pathogen and in this way the pathogen is destroyed now it has various modes of action which helps you increase the pathogen destruction first of all it labels the pathogen making me easier for the phagocyte to recognize it and that will engulf it in neutralizes any toxins produced by the pathogen and it also causes the bacterial cell to burst open Cajun lastly it makes the pathogen stick together with the answer relating to the lymphocytes notice that I use lots of keywords antigens antibodies for example try and include as many keywords as possible just shove them in your answer because if you look at my schemes they'll be underlined as being worth mark each so it's worth watching them in anyway don't just keep repeating yourself you need to insert lots and lots of keywords here lastly vaccinations vaccines so obviously when you're going on holiday somewhere tropical you might need to go to the doctor to get some vaccines now what these are is they're injections containing either a dead weakened or attenuated form of the pathogen that means it contains the pathogens antigens now in his antigens enter your body clearly your lymphocytes are going to be set off and they're going to produce antibodies which actually respond to those pathogens and some of those lymphocytes turn into torts called memory cells those memory cells remain in your body and therefore if you become infected at a later date with a much larger amount of that pathogen there are memory cells already in place which can secrete antibodies very quickly much faster much sooner and in a much larger quantity and what that means is that pathogen can be destroyed before it can take ahold of your body so the whole point of vaccination is to inject a harmless version of that pathogen so that if you accidentally become a factor there later day it can be destroyed before it can take hold so let's look more closely at some vaccinations which are made so dead pathogens are used to in the night against whooping cough we used a weakened form of the pathogen to treat measles and also tuberculosis and then lastly we just inject the antigens themselves when we're treating influenza five immunity is just a ton describing when a large number of people get vaccinated against something because something like measles virus will need a large number of people - in fact all in fact a person who will then go and infect another person that will go and infect another person and that's how the measles virus to spread now obviously if you go and Maxon eight loads of people against measles virus they were going to not be enough people for the measles virus to spread properly between and that's how you actually get herd immunity against something like measles basically means when a large number of people are vaccinated against a specific disease if you want to kill a pathogen like a bacteria you're going to have to use an antibiotic and antibiotics only work on bacteria they do not work on viruses so I've already described one problem antibiotics which is that they're only effective against bacteria the second problem is that increasingly we're seeing antibiotic resistance and that's what happens when we don't complete the course of antibiotics that we're taking if we over prescribed them because you find that you'll get some strains of bacteria which are actually resistant to the antibiotic and then before you know it all the new bacteria that are being made are resistant so back in the day when a certain antibiotic would work you're finding later then it doesn't work and obviously that's going to cause massive issues if we don't have antibiotics that work now in a laboratory it's really important that we use aseptic techniques and that's basically to prevent contamination by microorganisms and there's lots of different things we can do and that includes sterilizing a variety of equipment that could be using an autoclave which is a special machine manufactured in order to sterilize it could be just using a hot flame and if you've done any work at school maybe using petri dishes remember you're supposed to cover the petri dish straight away to prevent airborne contamination and you need a sterile growth medium so if you're providing your whatever it is you're trying to grow like that bacteria you need to provide them with a sterile agar jelly so let's make notes on that now so why do we use a septic tank technique well fundamentally it's to prevent contamination by microorganisms and how can we do that by a variety of sterilization techniques so we can sterilize our equipment using an autoclave when we're using petri dishes we use sterile agar jelly and lastly again using petri dishes we cover our petri dishes when not in use to prevent airborne contamination next up we need to look at petri dishes with a petri dish is a little plastic dish which we use to grow bacteria on because we're interested in that bacteria how it grows and how we can actually prevent its growth using antibiotics but in terms of preparing a petri dish for inoculation first of all you need to get an inoculating loop which is just a metal loop that you effectively swab the bacteria onto but you first will need to disinfect that loop to make sure there's no bacteria pre-existing on it and you need to dip it into a blue flame of a Bunsen burner again to ensure that it's totally sterile at this point you're going to swab it on the bacterial sample that you're interested in and you're going to wipe it across the agar jelly that's inside your petri dish now the agar jelly is the nutrient medium which means that it's full of food that the bacteria can feed on at this point you're going to place the lid on the petri dish and you're going to just make sure that some air can get into that petri dish to allow the bacteria to aerobically respire and then you want to seal up the tape just to make sure that nothing spills and that is how you're going to set up your inoculation and your petri dish a small bit where we dip into mats now so remember if you have a petri dish so we're looking down on it and then we put various antibiotic discs down and I'm going to call them a B C and D and now the bacteria starts to grow and then if they reach a very effective antibiotic let's pretend B is extremely effective then they can't grow around that disk say a is a not very good antibiotic so the bacteria can grow pretty close to that disc D we're going to say is an excellent antibiotic so it's going to have a huge clearance zone and then again with C we're going to say that it's not a very good antibiotic for this particular bacterium it hasn't managed to kill much the bacteria so as we can see very little clearance and the Green is obviously the bacterial growth so how can we actually work out that clearance zone well it's a roughly circular shape so we're going to calculate the areas and formats how do we calculate area by pi r-squared and r is the radius of the circle so if we take the clearance circle for D this would be R and then we need to square it and times it by PI to work out the area and as I said this is used to analyze the effectiveness of an antibiotic on bacterial cultures and the larger the area the more effective the antibiotic let's talk about how we actually go about developing drugs and to treat ourselves so in terms of what we're after from a drug obviously you want it to be effective because what's the pen taking drug that doesn't actually work you want it to be safe so you don't have it causing any adverse effects on your house because that wouldn't be great you want it to be stable and what that means is that it needs to be easily stored you don't want a job that can only be taken within like a week and then goes off in the cupboard and starts closing like problems you want it to be nice and stable and lastly the least obvious one it needs to be successfully taken into your body it's so easy to deliver whether that's drinking it or having it injected and it needs to be able to be removed from your body too but don't you notice that lots of drugs come from plants and lots of these plants are highly prized and obviously you can't get some chemical implant and then just give it straight to someone because you don't know the effects that will happen it may kill them so the relaxant stages involved in the development of a drug the first stage is preclinical trials and that's when they test a chemical or drug out on tissues or cells or other animals and that's where animal testing comes in and that's why also people have lots of problems with animal testing and I understand that once they've tested out on the animals on earth ourselves they will then start testing the mount on human volunteers and we call that clinical trials and I'll start by giving human volunteers very very small amounts so that if there are going to be bad facts hopefully they're not going to be too dangerous and then they'll increase that dose the amount that they give the person bit by bit until they're happy that it's the right amount when you're talking about actually doing training there's something called a double-blind trial and that's where neither the doctor nor the patient know whether they've been given the drug or not and that's essential because a lot of times if a patient is given a drug they're told that it's really going to work they actually kind of get themselves better through their mental state of mind they'll be like wow I've been told this drug will work so I'm going to get better because of it I know that's always giving you a false positive result but this is not necessarily a drug doing that so double-blind trial is when neither the patient all the doctor actually giving the drug know whether the patients have the drug because the other thing they could be given is a pissy Bo and a placebo is just a tablet that's like made out of sugar that has no drugs in it so some patients will be given a placebo some will be given a drug and then you look at the results to try and work out how effective that drug is now we're getting on to the tricky topic on monoclonal antibodies so what we're talking about here is a new development it's a new technology and we meet the first will understand what the word hybridoma means and all that means is it's a new cell type formed by combining Mouse cells human cells and cancer cells in order to form a new type of cell so I've already told you that lymphocytes will produce antibodies which will go ahead and destroy pathogens but the problem with lymphocytes is they don't actually divide and grow so in an ideal world we'd get a load of songbirds lymphocytes cause them to divide to make loads of antibodies and then go around treating people using these antibodies I've just said that lymphocytes don't divide so what we need ID is a type of cell which divides rapidly and in this case we know that cancer cells divide very rapidly because they go ahead they form tumors that's a really tall thing about cancer cells as these tumors that grow and obstruct parts of our organs so if they're in our brain of our heart that's where all the issues arise from the cancer so if you can think you could get a lymphocyte that's producing all those awesome antibodies that will go and kill stuff but then you've got the cancer cell which has the ability to copy itself and divide lots imagine if you combine them then you'd have the perfect situation where you're going to generate lots of antibodies that will go ahead and kill stuff but won't be cancerous and therefore won't cause any problems and that's really what this monoclonal antibody stuff is all about now what does the term monoclonal antibody mean well it's just a protein which is made to target specific cells so the crucial thing here is they're very specific now they've found that mice lymphocytes so that little mouse they found that lymphocytes and Seifer mice are amazing at producing these monoclonal antibodies so they combined it with the cancer cell in order to form this hybridoma which i've already mentioned and then that could go ahead producing all the antibodies needed to destroy dangerous cells I mean the obvious problem with there is that they come from ice and obviously are what is going to recognize my cells as being foreign and then our immune system will try and attack those myself so what they then did was they combined them with human cells in order to prevent the rejection issue and that's why the hybridoma is a combination of mouse human and cancer cells so how come on of clonal antibodies be used for firstly pregnancy testing because there's a hormone called HCG which pregnant women make now what happens is the monoclonal antibody can actually bind to that hormone and then it gets expressed in urine which can then be detected so it's actually impossible to get false positive results you will not get a false positive result you will definitely be pregnant if you get a positive results so don't yeah I think that's quite a sexual life point right that second thing that you can use monoclonal antibodies is for detecting disease because it can actually bind to disease cells and that's used to detect prostate cancer in men for example and lastly you can use monoclonal antibodies to detect levels of hormones so an example of this is you know how people donate blood because blood donations are really important but obviously you don't want someone with the disease AIDS or HIV donating but the facts go and infect the poor people that the Bloods being given to you so monoclonal antibodies can actually be used to screen that bird and see if there's any HIV in there really really good stuff now how come on open lines what is be used to treat cancer because really that's what we're after that's the really amazing role that they before so first of all they can help carry toxic drugs to the cancer cells and therefore those toxic drugs can go to work on the cancer cells without affecting our normal cells secondly the monoclonal antibodies can help trigger our immune system up to actually go to attack those cancer cells whereas before it might not have been doing that and thirdly those monoclonal antibodies can block the receptors on cancer cells and those receptors are needed to help that cancer cell divide to form a tumor so if it blocks the receptors they can't divide anymore which is obviously essential to prevent Shumer growth now we need to look at the advantages and what I've learned what is the first thing is that they have no effect on how C sells and that's crucial because a lot of cancer treatments such as chemotherapy and radiotherapy do go and damage a lot of healthy human cells which is obviously not what we're wanting the second thing is that the monoclonal antibodies can be used to treat a wide range of conditions however suddenly there are disadvantages that is some side effects can arise from using monoclonal antibodies and actually the technology involved it's been tricky to develop much trickier than they first imagined when they first started developing this so let's look at some examples of some key non communicable diseases we've already touched on a few of them but I want to create quite a large list here and remember these are diseases which are due to our lifestyle choices due to genetics they cannot be passed on from one individual to another they can't be caught for example by airborne transmission or waterborne transmission so we've already mentioned genetics so faulty genes and there are lots of example of genetic diseases such as cystic fibrosis sickle-cell anemia Huntington's disease another type of non communicable disease is due to malnutrition or a deficiency disease so this is when you don't have a balanced diet and your diet is deficient in particular minerals or food groups so if you don't have enough protein you get a disease called kwashiorkor my Rasmus is also due to a lack of protein scurvy comes about due to a lack of vitamin C and anemia is a result of a lack of iron and that makes you feel pretty exhausted looking at lifestyle choices now so what sort of unhealthy habits do people develop and what kind of diseases does that give them so if you smoke you're more likely to get lung cancer if you drink too much alcohol then you give yourself liver disease and that could lead to liver cirrhosis obesity so overeating can lead to diabetes type 2 and touching more on liver disease particularly in the UK it is very common it's actually the fifth high school of death in the UK and a large part of that is due to alcohol consumption increasing so we looked at obesity but how do you decide if someone is obese whether they're morbidly obese or if they're a healthy weight well we have different ways in which we can determine this and one of this is calculating the BMI and the BMI stands for the body mass index and you calculate that by finding the person's mass in kilograms and dividing it by their height in meters and you need to square that and in terms of the values if you have a BMI of over 30 then you're classified as medically obese however it's not a perfect way of measuring whether someone's obese or not because people for example that work out a lot and build up lots of muscle they're going to be correspondingly pretty heavy and therefore register as obese when clearly that just muscled looking at coronary heart disease now coronary arteries coronary means relating to the heart so the heart has its own special network of vessels which supply the heart with its own supplied oxygen it can't actually obtain its oxygen ease from the blood flowing through it has to have its own special set of vessels we call these the coronary arteries and they're famous because this is how people get heart attacks they get blocked they get obstructed and it does mean that oxygen can't reach the heart muscle so part of it dies which is what a heart attack is so first of all what factors increase your chance of getting coronary heart disease so that could be a sanitary lifestyle and lack of exercise could be your diet eating diets high in fat and sugar it could be inheritance so genes some people are just more susceptible than others because of genes that they've received from their parents it could be diabetes diabetes and coronary heart disease are very closely linked stress as well people shouldn't get too stressed because that can put a strain on that heart too so how can cardiovascular disease be treated so fundamentally if you change your lifestyle so you make healthier choices such as exercise anymore if you have a smoking habit give up smoking if you've gone a bit too far down the line where lifestyle changes aren't effective enough then you have to go for a surgical procedure and this includes that see what my drawings doing today if you've got a narrowing of your artery due to a fatty deposit on its walls then they can put in what's called a stent which is like a wire mesh containing a balloon which they inflate and that helps to widen your arteries and we call that a stent and then coupled with surgical procedures but slightly less hardcore is medication my granddad had cardiovascular disease and I remember he was given aspirin to help thin his blood right I hope you found my video helpful guys these are are so difficult to make but I know you guys really like to just sit and watch the whole thing in one so please give me a like like this video if you found it helpful it is a good incentive for me to continue my work and don't forget to stop I'm gonna soon with another video bye [Music] you [Music]