okay folks welcome to national four and five m cells and stem cells now in this topic we cover national four key area eight which is cell biology controversial techniques what we're going to do is investigate and debate the use of stem cells so how we're going to start is we're going to look at what all organisms are made of and organisms are made up of units called cells now cells are the building blocks of life all living things are made up of cells now cells are microscopic so that means we need to use a microscope in order to see them and we use stains such as iodine to help us see the cells more clearly so cells are the smallest structure that are able to lead an independent life which means they can live all by themselves one cell can level by itself and perform all the functions required for life now what we're going to spend a lot of time doing today is looking at animal and plant cells and the parts within animal and plant cells and yeast and bacteria and what jobs these parts do so on the left we have an animal cell and on the right we have a plant cell so i'm going to go through the structures and their functions so common to both animal and plant cells we have a cytoplasm now the cytoplasm is a jelly obviously it was jelly-like structure and that's where all the chemical reactions happen and chemical reactions are required for life so all the reactions happen in the cytoplasm the jelly-like structure of the cell then we have a nucleus so the nucleus is common to both animal and plant cells and a nucleus controls the cells activities for example metabolism ribosomes are spherical structures in the cells sometimes attached to a structure called an er but you're looking for a sphere a spherical structure in the cytoplasm and they're very important because they're the site of protein synthesis that's what all the proteins are made in your cells now we need proteins because proteins are part of a structure of cells our antibodies are made of proteins they help us fight disease our hormones which are chemical messengers that tell our body what to do and our enzymes which are the same which are involved in chemical reactions so ribosomes are where proteins are made we also have mitochondria which are common to plant and animal cells and i always think they look like teeth they look like a structure between teeth and if you think about association um mitochondria are where energy is made in the cell like you get energy from your food you eat your food teeth everything teeth energy okay so mitochondria is site of energy production in plant and animal cells and cell membrane again is common to both cells and a cell membrane is the skin of the cell and it allows small molecules to enter and exit now as i said plant cells have all of these structures but they have three additional structures they have a chloroplast they chloroplasts are where they make their own foods where they produce their own food and you sometimes find plant cells called producers because they produce their own food from scratch and to do that they need chloroplasts because chloroplasts have a pigment inside them called chlorophyll that can trap light energy and that light energy can be changed to the energy stored in food plants also have a vacuole which is like a bag full of sales sugars and water and they also have a cell wall which provides support and structure to the cell so when you're thinking about animal and plant cells you need to know the five structures are common to plant and animal cells and it's the additional structures that plant cells have now we're going to look at yeast now yeast is a type of fungus and it has structures common to animal and plant cells can you see structures that i would find in both animal and plant cells in the yeast so what we should see is the cytoplasm the ribosome the mitochondria the nucleus and the cell membrane are structures we'd find in plant and animal cells can you see a structure that's only found in a plant cell well done the cell wall so a yeast cell has all structures that both plants and animals have in terms of the two together so we have cytoplasm ribosome mitochondria nuclear cell membrane all these structures that has one additional structure that plants it has on this diagram which is a cell wall now not included in this diagram you will find that yeast cells also have a vacuole can you remember what the vacuole was it was a structure that holds cell sap so a yeast cell if you think about all the structures that an animal cell has and then two additional structures that the plant cell has the cell wall which provides support and the vacuole that contains the cell sap and we can only see the cell wall in this diagram and that's a yeast cell or structure what therefore does the yeast cell lack that other plant cells may have well done chloroplasts we don't see our chloroplasts we don't see chloroplasts in yeast cells now we're going to look at bacteria now bacteria are primitive cells can you pick out structures that we find in both animal and plant cells together well done so animal plants are the ones that they have in common here we've got ribosome cell membrane and cytoplasm so you'll find them in both animal and plant cells can you see an additional structure that i'd already found in a plant cell we've done the cell wall which should offer support can you see anything missing let's start with something missing that only found in animal cells and plant cells combined what do i find in both animal and plant cells that is not here so we should have gathered there's no nucleus here there's no nucleus that's a structure i would find in both plant animal cells and there's no mitochondria which is energy site of energy production can you see a structure that's not in the bacteria cell that i would find just in plant cells so we don't tend to find a vacuole and we don't find chloroplasts now that doesn't mean the bacteria cells can't be producers they can't make their own food they tend to just have the pigment but they don't have the chloroplasts so let's have a closer look at this in a bacteria what you find is a cell wall a cell membrane doesn't have a nucleus it doesn't have mitochondria but what you do find are ribosomes and cytoplasm now how does that control cells activities well bacteria cells have a plasmid it's a circular dna structure that allows it to do just that okay folks we're going to go through the different organelles where they find them and what their job is so let's start with the nucleus what job does a nucleus do we should have it control sales activities and where would i find a nucleus what cells we've looked at animal plant fungus and bacteria remember fungus is yeast good we find it we find the nucleus in animal cells plant cells and yeast cells bacteria doesn't have a nucleus what does bacteria have instead of a nucleus ah plasmid so cytoplasm what does that do the site of chemical reactions and where do we find the scientific way would we find cytoplasm what cells have cytoplasm so we should note that it's all cells all cells have cytoplasm all cells require chemical reactions to happen what does a cell membrane do so cell membrane controls what enters and exits the cell only small molecules can enter and exit the cell what cells have a cell membrane all cells now let's think about mitochondria remember that was this that was the structure with tiny teeth that like looks like teeth what was the job of the mitochondria what was the association with teeth energy teeth foods energy so mitochondria are the site of energy production what cells do we think mitochondria and remember we've done we've looked at animal cells plant cells used cells and bacteria cells all cells accept bacteria ribosome what happens at the ribosome what's the job of the ribosome that's where proteins are produced proteins such as enzymes for chemical reactions hormones structural proteins antibodies so what type of cell has ribosomes so we should have all cells so so far cytoplasm cell membrane and ribosome are common to all of the cells that we've learnt cell wall what does the cell wall do well done that offers structure and support and what cells have a cell wall think about ourselves animal cells plant cells she sells bacteria cells so we should have all cells except animal cells have our syllable and what does a cell will do again it provides structure and support to vacuum the cell job with the vacuum now the vacuum is like a carrier bag if you like it's a bag and it stores cell sap and for example salt sugars liquids what yourselves have a vacuole so in this case plant cells have a vacuole and the other cell that had two and parts the parts that plant cells have was there yeast cells so yeast cells remember that had everything that was common to both a animal and plant but two additional features would be only found in plant cells which was the cell wall and the vacuum and chloroplasts where do what cells have chloroplasts and we show that the only cell that has a chloroplast that has chloroplasts are plant cells now this is an activity again that you'll do in class so you'll be able to tell your teacher what job each of these organelles does and where we find them so let's do this kind of fast nucleus what does the nucleus do control cells activities and where do we find a nucleus do we find them in animal cell we do plant cell we do bacteria no we don't too primitive fungus which is yeast we do cytoplasm where do we find the cytoplasm yes we do find an animal and plants and bacteria and fungus what did the cytoplasm do it's a jelly-like substance like plasma jelly it is a site of chemical reactions cell membrane what's the job of the cell membrane controls what enters and exits the cell so do we find that an animal cell of course we do plant yes we do bacteria of course and fungus of course yeast has that too so again cytoplasm and cell membrane we find in all of our cells a vacuole what is that store sale sap do we have an animal cells no we don't plant cells yes bacteria no it's too primitive we don't find a lot of structures in the bacteria cell and fungus we do so yeast we do find a vacuoles so cell wall what's the cell wall for structure and support do animal shells have a silver no they don't plant cells yes they do bacteria yes they do and fungus yeast cells do as well remember yeast cells have everything common to animal cells and plant cells together but an extra two features that we just found in plant cells and that would be cell wall and vacuum so chloroplasts do we have chloroplasts remember chloroplasts are the site of photosynthesis we don't have chloroplasts and animal shells animal cells do not have blood plastics we are not producers we don't make our own food or produce their own food plant cells correct bacteria no we don't find chloroplasts and bacteria but see they can have chlorophyll they can be producers but we don't find them in that structure and fungus yeast did you have chlorophyll do that have a chloroplast no they didn't and mitochondria and i remember mitochondria it's an odd-looking structure and i say as i said before looks like it's got weed teeth what does that remind you of teeth food that's the site of production so animal cells they have them plant cells yes they have them bacteria no they're too primitive fungus yeast cells do as well ribosomes what are ribosomes they're the site of protein synthesis we find them are spherical structures that we find in the cell cytoplasm so that would be your ribosome there could we find a ribosome do animal cells have them yes they do plant cells yes bacteria yes and yeast yes and a plasmid what was a plasmid again a plasmid was in place of a structure plasmid is a circular ring of dna and it's in place of the nucleus and the only cell that doesn't happen nucleus is the bacteria so bacteria instead of a nucleus have a ring of dna that control cell activities called a plasmid so let's have a look at the summary here we can see that all cells have cytoplasm cell membrane and a vacuole and only plant cells have chloroplasts and only bacteria cells have plasmids now we talked about unicellular organisms cells that only exist of one cell so they can carry out all the functions and are capable of making all the chemicals that they require to to survive and that they are usually bacteria now we're going to look at cell types and animals because we've looked at basic cell structures but cells take on a variety of different shapes and structures in order to do a particular job and we call that specialization so cells become specialized to do a particular job and to do it very well multicellular organisms are organisms are made up of more than one cell human beings are an example of that they're composed of many different cells and these cells are arranged into groups called tissues and the tissues work together to perform a function so if we have a look at a few examples here we've got red blood cells so red blood cells have taken a particular structure they're biconcave in shape they don't have a nucleus and their job is to carry oxygen around your body so their structure suits their function very well if we look at the bottom left that is a nerve cell now a nerve cell's job is to transmit impulses electrical impulses with messages from one part of your body to another and the nerve cell structure suits its function to be able to to do that it's long in length and able to have electricity passing along the length of it now cells can vary within a tissue so if you think about blood as a tissue you have different types of blood cells within that tissues we have red blood cells we have white blood cells and platelets we've already discussed red blood cells as carrying oxygen around your body white blood cells the job of white blood cells is to fight disease so with any tissue you can have different cells working together cell types and plants cell variety is more apparent when comparing different tissues so here we have two different tissues and plant cells we have um xylem and flour and we can see they're very very specialized groups of cells cells don't look all the same they're very very different and if we look at xylem to the left xylem really is dead hollow tubes very specialized and job of xylem is to carry water from the roots to the shoots and you'll learn more about that later on and flow them to your right again very different looking cells the job of form is to transport sugar around the plant so we can see the specialization in cells so when we're talking about multicellular organisms we have a hierarchy if you like multicellular organisms have more than one cell and the cells are organized into groups called tissues and the tissues are organized into organs and they're specialized for their function and they work together to form organ systems now specialization of cells leads to the formation of a variety of cells tissues and organs which are groups of organs like groups of organs work together eh forming systems so what we have is cells grouped in tissues working together in organs and being part of organ systems and a tissue is a group of specialized cells that perform a particular function we know we've got different types of cells working together within a tissue and we call this division of labor so if we think about in terms of a hotel we've got different groups of staff working together so you might have the reception staff that are they are trained to do a particular job they're dressed in a particular uniform you've got the waiting staff you've got the catering staff the housekeeping for example you'll have the bar staff they all are specialized to do a particular job now we're going to be thinking about an animal and plant celesy so if you were going to take notes on what you've learned about animal cells what kind of points would you make i'm going to give you a minute to think about this okay so you might want to see that we know that animal cells have a membrane and what's the job of a membrane it controls entry and exit of small molecules we also know that animal cells have a nucleus which controls cells activities they have mitochondria which are the site of aerobic respiration or energy production as we can see at this stage and they have ribosomes which are the site of protein synthesis and they have a cytoplasm the jelly structure which is a site of chemical reactions now what i want you to do is take a piece of paper and try and think about how you would do an essay on plant cells so what you might have is plant cells also have a membrane which controls entry and exit small molecules they have a nucleus to control those cells activities they have mitochondria chief site of energy production ribosomes site of protein synthesis they have three additional features so you might have got chloroplasts which makes them producers they produce their own food by photosynthesis cell wall for support and structure and a vacuole for storing cell sap now what we're going to look at is um where all these specialized cells come from so we've looked at the basic cell the structure and function of the parts of the cell we've had we look at how sales are very different looking to suit the particular jobs we're going to have a look at where all these specialized cells come from and they come from stem cells now what a stem cell is is an unspecialized cell so before a cell has specialized or what we call differentiated which is changed to take on a particular shape it's called a stem cell so definition of a stem cell is a cell that has not yet become specialized but stem cells are able to become specialized cells such as nerve cells liver cells blood cells cardiac cells which do a particular job because they're shaped a certain way now growth in animals takes place all over the body and we need to replenish ourselves for growth and repair so basically stem cells are unspecialized cells are able to develop into specialized skills to allow us to put into growth grow and also repair anything that's become damaged so let's have a closer look at stem cells stem cells are biological cells they're found in multi-cell organisms and they can differentiate which means change their shape into specialized cells and they also self-renew we need stem cells to be able to make more stem cells now we have two different types of stem cells we have embryonic and adult stem cells now embryonic stem cells come from the embryo the start of new life and adult stem cells really are found throughout our life we have these stem cells throughout so let's think about where we all began we all began when the sperm met the egg so when the nucleus of the sperm fuses with the nucleus of the egg you produce a cell and that cell starts to divide into many more cells and that group of cells is called a blastocyst which is really an early embryo and that's full of embryonic stem cells that are very unspecialized at the moment but will still from you to make more of themselves and differentiate or specialize into all the different cells that make up you so here we have sperm maternity egg fertilized egg our blastocyst philosophers that's themselves able to specialize to produce all the cells that you need in your body so that's embryonic stem cells now adult stem cells are found in certain parts of your body and they are really for growth and repair so for example the stem cells in your skin will become more skin cells and stem cells in your bone marrow will differentiate into more blood cells red blood cells white blood cells and we need these new cells for growth and repair so what can adult stem cells do so um the stem cells found in our bone marrow can differentiate to form new blood cells so for example red blood cells white blood cells to fight it will help us fight disease so what can what stem cells are all about really two different job stem cells have to do they have to make copies of themselves to keep the number of stem cells high and specialized produce the specialized cells that we require in our body whether it's when we're becoming a human being from the embryo or throughout our life in terms of growth and repair so why bother with stem cells well stem cell research is carried out in order to test drugs understand disease and treat patients and we're going to have a look at that in more detail now test drugs what if for example a pharmaceutical company has come up with a drug and that can um help um treat liver disease now under normal circumstances we might taste on animals or do more human trials but we know that stem cells can become specialized cells so what if we were to grow liver cells from stem cells and tested drugs on the stem cells in the lab without the need or would reduce needs for animal testing and reduced human trials so what if we use stem cells to grow specialised cells and add the new drug to specialised cells and see what the drugs do what effect they have on a specialized cells and it might reduce needs for animal testing understand disease some diseases are caused by faulty genes and again what we could do is use stem cells create false and stem cells and use stem cells to study the disease really grow stem cells with faulty genes and work with these cells to see what has gone wrong and how it could be potentially fixed with treatment and finally treat patients so stem cells are used to make use skin for patients with bad burns so we have skin stem cells so if you've suffered a bad burn what if you use stem cells skin stem cells to replace the damage that was done to your skin there's a lot of prospects for stem cells the future might use stem cells to grow at new cells in other parts of the body cancer patients gets a new trachea grown from his own stem cells etc there's massive potential including treatments for diabetes and parkinson's disease however there is a catch and that's where the debate comes in the ethics of using stem cells the disadvantage is that some people believe that using stem cells from the embryo is destroying a potential life because that group of cells would have the potential to become a human being so the summary here is stem cells is a cell that's unspecialized that can divide to form more stem cells and also can become specialized cell the advantage is that we can discover new treatments for illnesses but the disadvantages using ambionic stem cells can destroy a potential life now we're going to have a look at processing skills in this unit so when we're looking to measure the size or sales and really what we're looking at here is a field of view which is if you were looking for a microscope this is what you may see so the example might ask you to measure the length of one cell or the average length of one cell now the important figures here that you need to look at are that the length of the field of view is 300 micrometers so from here to here it's 300 micrometers now how many cells do you have in that 300 micrometers 1 2 3 4 five six so what we're saying is six cells are 300 micrometers length so what would one cell be and it is one cell likely to be less or more than that figure less how many times less than three hundreds it would be six times less so what we're doing is we're dividing three hundred by six to get the length of just one cell let's have a go this question so the diagram below shows a group of cells as seen under a microscope the field of view was two millimeters in diameter calculate the average length of the cell so if we're assuming that the length of cells the length of the field of view is here and we know that that's two millimeters how many cells do we have within that two millimeters so we have one two three four five cells so what we're seeing is five cells is two millimeters in length now i don't want to know five i want to know one cell is one cell going to be less or more than two millimeters of course it's going to be less how many times less than two millimeters is going to be five times less so we need to divide by five which gives us our zero 0.4 okay folks let's try this question the diagram below is a group of cells as seen under a microscope the field of view is two millimeters in diameter calculate the average width of the cell so if we're assuming the width is this way again that's two millimeters either way it's two millimeters now how many cells have we got across the width of our field of view so we've got 1 2 3 4 5 6 7 8 19. so again we've got a situation where we're seeing that 10 cells this time as two millimeters now really we're looking for one cell as one cell going to be more or less than two millimeters is going to be less how many times less than two millimeters it's going to be 10 times less because we'll get 10 cells that'll bring us down to what the width of one cell would be which is 0.2 now we're going to look at changing millimeters to micrometers now if you ever look at millimeters on a ruler it's very small measurement now within that one millimeter if you look at it you have a thousand micrometers in there now the reason we're looking at micrometers is because we're looking at cells and they're microscopic you need they're so small you need a microscope to see them so we'd naturally be using micrometers to measure the length and width of cells and one millimeter has 1 000 micrometers in it so to convert millimeters to micrometers you multiply it by a thousand and to convert micrometers back to millimeters you need to divide by a thousand because there's one thousand more micrometers in millimeter okay folks we're gonna have we've got this question now so the diagram polishes are good for human cheek cells as seen under a microscope the actual diameter of the field of view was two millimeters and we know that one millimeter is a thousand micrometers so we have to calculate the average length of the cells in micrometer so we need to do two things here we first of all need to find out the average length of a cell and then we've got to do the conversion from millimeters to micrometers so the length of the cell and they've given the arrow to show what they're looking as length so across the way how many cells do we have in within that two millimeters of length we've got one two three four five so we're seeing five cells as two millimeters so we do the same thing again we want one cell is that going to be more or less it's going to be less how many times less well it's going to be five times less so we divide the two by five and that'll give us a point four now let's look at that zero point four because that's in millimeters now i know when i'm looking at a millimeter that there's a thousand more micrometers in each millimeter so how do i change 0.4 millimeters to micrometers i have to multiply that by a thousand to give us 400 micrometers okay folks the diagram below shows a group of human cheek cells i see under microscope this time the dia the actual diameter of the field of view was two millimeters to calculate the average width of the cells and micrometers so again we know that um the width is two so the field of view is two wherever you're going up or down so how many cells have we got within our field of view one two three four five six seven eight nine ten so what we're seeing is ten cells gives us a diameter of two what i'm with the two millimeters i don't want ten i want one is it going to be more or less than two millimeters one cell less how many times less ten times less because i've got ten cells so two divided by ten gives us the 0.2 how do i change the 0.2 which is millimeters and to micrometers again i know i've got a thousand micros in each millimeter so i need to multiply that by a thousands to convert millimeters into my micrometers remember there's a thousand millimeters and one micrometer now we're going to do some exam cell practice so the list gives four types of cells bacteria fungus animal implant give one structure that's also present in all of a structure that's present in all of these cells give you a clue there's three things to choose from ribosome can you think of the other two cell membrane and what's a gel-like substance the cytoplasm right which structural feature is found in a plant cell and not in an animal cell build on a cell wall which parts of the cell would be found in an animal cell so what we're looking at here is a plant cell so what we should have is n and o now what is n spherical structures in the cytoplasm ribosomes remember what the ribosomes did the site of protein synthesis and what was all look at the teeth energy production which is a mitochondria right so a is a cell membrane what's his job to control what enters and accepts the sale well done what gives shape and support the cell wall and what is in your cluster controls sales activities so when you're going to class you should be very confident answering these questions now new cells are produced throughout life then cells found in the early stages of an embryo's development which have the potential to develop into specialized cells quite cells are unspecialized but they can become specialized stem cells and remember the hierarchy in terms of cell the cellular hierarchy you've got cells that are organized into group of tissues it may find lots of different tissues in organs and then you get systems state of reason other than growth by cells continue to be produced throughout life growth hands what happens when you break a leg repair nemo structure present in plant cells which is absent from animal cells there's a few to choose from see a wall vacuole and chloroplasts remember animals are not producers they don't produce their own food and you need chloroplasts to do that what name is given to chemicals which are used to make cell structures more visible under a microscope stained an example of a steam will be id okay so i'm doing one option in each set of brackets to complete the following sentence correctly the basic units of living organisms are cells most of them can only be seen using a microscope when examining them they can be stained for example with iodine to make them clearer so what we're looking at here is yeast that's one of the key cells we've looked at so and what structure and i'm going to change the function here and i'm going to say support to provide structure and support so what structure provides support so what we should have here is a which is a cell wall now let's look at b what's b that's the cell membrane what's the job of the cell membrane to control what enters and exits the cell and what controls cell metabolism the cell metabolism is basically one of the sales activities so what control cells activities we've done the nucleus which is e okay so cell wall would be a the nucleus is e now i'm going to stop here there's many more questions that you can have a go at uh what i advise you to do is practice the essays plant cells animal shells have them have a read over the powerpoint again practice the question so when you come into class you have learning behind you and the learning will be so much easier for you well done you