this is the lecture for chapter 2 the self alright so we know the hierarchy of structural organization starts at the chemical level okay but those things are not alive right so when we think about biology biology is the study of life alright so if we're gonna start with biology okay the first level technically if our hierarchy then is gonna be the cell right so there's nothing smaller than a cell we can consider living all right it's the basic unit of all life it's the building block of all life all right so it's very important you understand this particular level the hierarchy because all of the levels on top of it all the subsequent levels after are built upon this foundation alright so starting off okay late 1600s Robert Hooke he's who we consider the father of microscopy okay he's the one who developed and invented the microscope all right now he put several things under his microscope you put you know I'm sure during this time okay every single imaginable thing and you can find that fit under his scope you probably put under okay one of the things he put under his microscope was a piece of wine cork all right so a piece of cork that winemakers used to bottle their one now cork comes from work well it comes from the bark of a cork tree alright so at one point right it was a living thing so when he put that piece of blank work underneath his crude microscope he drew the following image we see here on the right right and where as you guys know from okay our microscope lab unless you lay things perfectly flat on the microscope okay some parts will be in focus as we see here in white other parts will not be in focus okay what we see here in black okay so the parts we do see in focus okay he drew these would look like brick like structures over here these circle like structures and he saw those and he said himself well those look like cells today cells that monks in the late 1600s used to live in tiny rooms right and we use the word cell today okay in this case it's not monks living in these cells it's prisoners living in these jail cells all right so he's the first person actually to see a cell under a microscope okay so he actually coined the term cell right and it's still the same word we use today describe these basic unit of life these building blocks of life we call cells today is a little bit later in 1830s right Mattias lied in the Theodor Schwann by this point I 230 years later they have more sophisticated microscopes right they put stuff under their scopes also I assume all right and they also put living things okay and every time they put a living thing underneath their microscope okay what did they notice well they notice that all living things are composed of one or more cells okay and that's a principle that we still hold true today okay if you're looking at something living it has to have at least one cell all right so here's our hierarchy okay so here's our chemical level all right atoms and molecules okay we're right here okay in the grand scheme of this entire hierarchy okay we're starting right here at the cellular level all right and then we know that well when you have cells working together okay to provide a common function then we have tissues and then we have tissues coming together to make organs organs typically don't work on their own to make organ systems okay which then all work in a concerted effort for them the survival of the organism all right now above that you can have populations you can have communities okay you can have ecosystems alright so but in terms of where we're at right now in this class we're right here at the cellular level all right so one thing about cells is that they're not all the same okay and they all have different structures okay so we know that structure determines function so here is a collection of different cells they're not all human right some of them okay for example bacteria right these are unicellular organisms for example there's one bacteria and then we would consider this a colony of bacteria all right and then they have archaebacteria okay they were once thought to be okay the same as new bacteria okay the fact that they both didn't have a nucleus okay but upon DNA sequencing they found that arctor bacteria actually quite different from bacteria okay these ones here are very primitive organisms they live in very extreme conditions for example near the heat vents at the very bottom of the oceans all right and then we have cells that belong to his blood cells all right some of the cells are very flat these are the red blood cells some of them are a lot larger okay these ones here we call the white blood cells or the leukocytes and then we have platelets all right so we see though even within our blood we have different cells of different structures why because they have different function and I thought this was cool these are dinosaur cells all right here's some algae here's some plant cells right and then we have cells that belong to MS intestinal cells and neurons okay so neurons again they look really funny and they have all these little branching processes that come off of their cell body well why do they have to do that well because they have to send information right from one part of your body to another part of your body okay so we can structure determines function all right and then here and we see these intestinal cells right these are the cells that line your intestines your digestive tract okay so each one of these purple dots represents one nuclei okay so you're not just looking at one cell here you're looking at many cells present on this slide all right so they do different differ in shape they did they do differ in appearance in morphology okay and the reason why again is because they all have different functions now besides differing in shape and morphology okay they also differ in their ability to move right so really the only motile cell present embodied okay they can move from one part to another okay our sperm cells right the male gametes that have to swim through the female reproductive system right fertilize the egg within the fallopian tubes right now there's some other cells that have cilia okay on them nice so if you guys remember from from lab right in the epithelial tissue lab right pseudo stratified ciliated kamar okay so those cilia present on the apical surface allowed in those cells to propel mucus okay on that hip local side of the upper foot now they also differ in what well their internal organization some cells okay for example have a nucleus we call those eukaryotic stem cells don't have a nucleus we consider this prokaryotic now in addition to that okay the type of structures you find inside of you cell they couldn't differ from from one another okay so a cell that needs lots of energy you're probably gonna find lots of mitochondria okay a cell that does lots of detoxification you're probably going to find lots of peroxisomes and so forth and so on okay so whatever function that cell does for that organism okay it's organization not only external organization but it's also its internal organization it can be different now their metabolic activities okay it coincides with the same thing right in terms of what's happening Emma Koryak shion's I say a liver cell does can be completely different from the type of chemical reactions okay that a neuron does in your brain all right so a enzymatic activities and chemical reactions caking can be different from one cell type to another cell type now they are different they're different in shape they're different in structured they're different in their ability to move their internal organization what they do chemically okay but at the same time they are similar to one another okay so taking a neuron and a liver cell again okay yes they do different things but there might be some overlap okay in terms of what a liver cell does and what a neuron does there could be commonalities in terms of what type of reactions they do okay now going back to the bottom of the hierarchy the chemical level K so atoms and molecules right so here are the four macromolecules that we find k present okay that kind of make up the human body right so proteins carbohydrates lipids and nucleic acids alright so the question is are the following organic molecules alive yes or no well you know the answer that question right the basic unit of all life is the cell these are smaller than itself okay so we do not consider proteins carbohydrates lipids and nucleic acids life okay they're used to build life but by themselves individually they are not alive okay so the cell theory is that all organisms are composed of cells and sell products all right so something as small as a bacteria it's considered a lie because what yes they're only made up of one cell but they are made up of one saw all right us as humans we are multicellular organisms we're made of 100 trillion cells okay so all cells come from pre-existing cells all right so these two cells down here okay where do they come from well they came from this cell here so I can't just take proteins carbohydrates lipids and nucleic acid I can't just take them all together shake really hard in a jar and say oh wow I just made some cells I created life right now okay and that's not how it works right so if I call these the daughter cells well they came from a parent cell then okay all right what else can we say about the South Area okay well are all the organisms within an organism the same all right so I try to find a figure on the internet that would show you know a human made up of multiple cells and this is kind of the best one that I found I should actually have to look again maybe there's some better ones okay but here's this basketball player with this whack-ass form in terms of a jump shot I don't know what that guide hand is doing up there okay but we see that this humans made up of what blood cells nerve cells muscle cells intestinal cells right so yes we're made up of 100 trillion cells okay but in terms of the 100 showing they're not all the same we have the different distinct cell types right around 210 okay so here's a better site here's a frog okay and you see this frog is made up of blood cells of nervous tissue cells of muscle cells of epithelial cells of connective tissue cells right reproductive tissue so each organism is made up of different cells okay and those different cells allow them to make different tissues alright so how many distinct cell types make up human body yes we have a hundred trillion but we have 210 distinct cell types all right so one thing to do to appreciate okay what a cell is okay we're gonna start off very very broad and then work our way down okay to the cells and human beings all right starting off with this also okay where did you come from right okay the one hundred trillion cells that make up you as an adult okay where did they come from well dad did something really nice for Mom right I don't know what he did okay but a cell called a sperm cell okay came together with another cell called an egg or an oocyte okay and when that sperm fertilized the egg you produced a single cell here known as a zygote all right so this I goat is the fertilized egg okay so this is gonna have information that you got from your dad this is gonna ok have information that you got from your mom okay we all started our lives as a single cell called a zygote okay and there's someone at home say none I did it yeah yeah you did okay when that's sperm and that egg came together during the event of fertilization you were conceived all right and here is that single cell here known as a zygote we all started here right and then what happens well the cell divides right now what are you gonna notice when it divides the diameter the overall diameter if I compare the diameter this with diameter this it didn't change okay but the number of cells did change them basically cut this one large cell into two smaller cells okay and then these two smaller cells divide two forms four cells okay notice the diameter hasn't changed the cells has gotten smaller okay and these four cells divided the form eight cells and the eight cells 16 the 16 to 32 32 to 64 64 to 128 okay 128 to 256 and we divide hey the diameter doesn't get bigger okay but then the cells get smaller and smaller and smaller and smaller okay and we form a solid ball of cells again it's called a more you luck you know if they know that okay but this is called amarilla and we divide even more and the cells get even smaller okay and then we form a hollow ball of cells look if I were do a frontal section through it it's Hollow okay and this hollow ball of cells we call this a blastocyst okay and inside that blastocyst you guys can see these purple cells inside our hollow ball okay and these are the embryonic stem cells okay these are the cells that are a army potent okay if they're given the right signal they'll become your brain if they're given the right signal they'll become your digestive tract it for the given the right signal a they'll become connected that we're here for example right if you give the right signal this will become a nervous tissue okay someone has a spinal cord injury oh let's get some embryonic stem cells and they try to convert that so we feel this person okay but the controversy with harvesting embryonic stem cells is that you need to kill the embryo all right so this this this debate of whether embryonic stem cell research is moral or not okay it all depends on where you believe okay your life began okay did it did it begin at conception well in that case harvesting embryonic stem cells from embryo means you have to destroy the embryo okay or are you on the boat of okay life begins and when we're born okay in that case well does it matter okay that you then okay harvest okay embryonic stem cells so we're gonna get into that discussion here but that's where the discussion lies okay where does life begin where did your life begin basically right so from this one start this humble beginning when we were conceived as a single zygote through many rounds of cell division and then differentiation what happens with these embryonic stem cells is they start to differentiate they become different parts of your body they go through a process called gastrulation some of these embryonic stem cells become an ectotherm in blue some of these embryonic stem cells become this mesoderm in dark pink okay and then some of these okay embryonic stem cells become this yellow layer here the endoderm okay so what does that mean becoming the ectoderm in the mesoderm and endoderm well the ectoderm the blue stuff becomes this part your brain and your spinal cord the retina and your lens right your hair your your epidermis the outer part of your skin what about this dark pink stuff well that's gonna be your skull in your head in your skeleton in your heart and your spleen well what about this yellow stuff here well become your digestive system right your stomach your calling your liver your pancreas right I'll see your Reaper your urinary system urinary bladder so forth and so on right so we all start our life as a single cell called a zygote and through many rounds of cell division we started accumulating enough sells them to lay out the body plan that becomes now different parts of your body okay so the one hundred trillion cells came from that one single cell okay when we were conceived and called the zygote all right so what is that embryo embryo do okay well it latches onto the wall of the uterus all right so here's the uterine wall here's the embryo okay we start to differentiate some of these become okay the epidermis and your neurons and your pigment cells and your sperm and your egg and so forth and so on okay eventually this becomes a fetus okay and then the fetus okay at that point okay once it passes through okay the birth canal okay is now known as a newborn baby all right okay so a tour of the cell okay a bit of review so hopefully you you're more appreciative of what a cell is you started your life as a cell called a zygote all right so all living cells fall on earth fall into two different categories okay prokaryotic cells and eukaryotic cells okay so what's the difference between the two well prokaryotic cells Pro means before you means true okay so what does carry mean meant now what means littlenut right so who ever looked at cells under a microscope they saw that inside of a cell there was a little nut and that little nut okay is called the nucleus so pro means before the nucleus you means true nucleus so those cells that have a nucleus we call those okay eukaryotic cells those cells that lack a nucleus we call those prokaryotic cells alright so pro Kotik cells okay these are very simple organisms like bacteria and archaea all right eukaryotic cells these are typically more complex organisms right like plants animals right you may have some unicellular organisms hey that have a nucleus well they're little more developed in up from then then back to here or archaea okay so if you have a nucleus eukaryotic if you don't prokaryotic okay so what type of cells do we have as you well majority of our solos are eukaryotic in terms of they have a nucleus right now besides having or not having a nucleus what else are some differences between prokaryotic cells and eukaryotic cells well prokaryotic cells are tiny they're very small okay as opposed to okay you card excels relatively speaking are humongous compared to prokaryotic cells so why the difference in morphology in terms of shape okay in terms of size well if I'm a pro at Excel you're not doing very many complex we're gonna mechanisms okay you're doing some reactions probably okay for energy right to reproduce right to get rid of waste right as opposed to you get excels there's a lot more complex reactions occurring on here okay so I'm talking about sending electrical information one from one part of my body to another like a neuron if I'm talking about okay detoxification and all the good stuff if I'm talking about right intracellular digestion producing okay lots of lysosome in terms of chemical reactions eukaryotic cells okay do a lot more than these prokaryotic cells so the analogy I can give is well compared to businesses right one company builds an entire car let's say Tesla right and another car just makes aftermarket parks for Tesla like they make custom okay steering wheels I don't know custom wheels and rims which one's gonna need a bigger warehouse okay the company that makes the entire car or they come in that genetics the steering wheels you're probably gonna need a bigger warehouse okay or factory okay for that company that makes the entire vehicle right when that just makes the aftermarket steering wheels probably not that big in terms of their Factory so the complexity of okay the cell okay corresponds directly then to the size of that particular song alright so if I'm gonna describe what a prokaryotic cell for the person okay for the person first time hearing what a prokaryotic cell is I'm probably gonna describe it as a studio apartment okay so close your eyes think of what a studio apartment looks like okay and what's what's what's popping into your head right now well you probably open the door okay and what do you see you probably see everything right where you sleep where you're gonna eat where you okay maybe you have a small bathroom maybe it's there also okay where you're gonna study so it's just a tiny room right there's no compartmentalization you walk you and you see everything so it's the same thing here with a prokaryotic cell you walk in you see the DNA okay yes it's in a region called the nucleoid region but it's there it's not separated from everything else okay you see all the different organelles you see the fluid everything is mixed in with one another okay so bacteria is a good example of a prokaryotic organism right so if you see on the next picture slide we see here here's the bacteria right here's the DNA and purple here all the ribosomes in blue here's all the fluid everything's mixed in with one another all right now in terms of eukaryotic cell okay I'm thinking more along the lines of compartmentalization okay things like an apartment things like a townhome things all right like a condominium things like a house a home okay so when you walk in okay let's describe your house right now okay so let's say you you finished anatomy fizz's fish you went to nursing ok now you're a full-blown nurse you're getting paid okay so let's see how well you're getting paid you walk in what do I see well walk and see a four yay right which means white line where you put all your shoes and stuff okay and what else do I see well then you see that there's a living room and a dining room and you see a kitchen you see a laundry room you see a garage you see wow you have a look alright you go upstairs you see rooms you see a laundry room you see a master bedroom okay you have compartmentalization one because each part of that house does something different you cook in the kitchen okay you wash your clothes in the laundry room okay you entertain in the dining room or family room the living room all right you park your cars in the garage you sleep and make all the decisions in the master bedroom can I go out tonight with my friends no you cannot go do your homework all right so when I look in a eukaryotic cell well there's the master bedroom there's the nucleus with all the decisions are made okay there's the kitchen right here these are the mitochondria is where we make K our ATP right so there's compartmentalization occurring in these eukaryotic cells why because the stuff that it happens in the mitochondria I don't want to interfering with the stuff that's happening in a lysosome the stuff that's happening the nucleus I don't want it okay it's have anything interfere with the stuff happening okay within a peroxisome so we have compartmentalization now when we talk about eukaryotic cells okay so you've gotta go we're gonna be unicellular like like like an amoeba for example or a Paramecium right or they could be multi-celled like human beings I could dog like your cat like the tree outside okay good examples of multi-celled organisms now within our bodies there are many different cell types right so we have a hundred trillion cells okay we have 210 distinct cell types okay the thing is though we're not gonna spend the entire term saying well let's go through all 210 one by one okay saw one will talk about the liver and then cell 2 we'll talk about epithelial and cell 3 we'll talk about neurons you know that take forever maybe a boring class okay so what we're gonna do is we're saying yes we have 210 different kinds of cells but at the same time what are we saying well yes they're different but yes they're similar okay so virtually they share the same basic parts and can be described in terms of what we call a generalized cell alright so this is a generalized cell okay so I'm going to describe a cell that is what that's basically pimped out it has every single thing a cell can possibly have right so we all ready to walk through your house right we saw the foyer and everything in the Nook okay so let's see how well you're doing right let's look in the garage what kind of car did you get okay and this kind of go back in time when you actually went shopping from that car okay so let's go okay what kind of car do you want to get some people say some wild crap sometimes right we'll just get basic here okay let's say we go to long go Toyota right and we're gonna buy I don't know a tundra or a Sequoia all right some big some big car okay and you go there right and salesperson walks up and this says what kind of car do you want well I want to get us a coil alright well what color looking for what do you know what kind of options do you want hey well you say you know I'm doing pretty well okay let's look at the limited and let's see okay the limited with all the possible options okay the different wheels okay sunroof okay radio leather trim alright everything I want to see everything the third row why are you doing that well because you want to see the pimped-out okay Sequoia okay and then the salesperson busts out the prize well this car is like you know eighty thousand oh heck no I just started my job I just bought a new house so I'm gonna say oh okay you can't you can't get the one that's all pimped out what about this one okay this one's just like the one you drove but it doesn't have this or this okay and can you picture that in your head yeah yeah you can picture their head you just saw the Sequoia that everything all you had to do is just subtract the two things that he said or she said isn't in this now okay cheaper models so it's the same thing yes we have 210 different kinds of cells they're all different than what they have inside them all right but we're gonna say well we're gonna talk about a generalized self this is the pimped-out cell it has everything so that when we approach another cell a couple weeks from now and we say well you know guys this is just like that general I saw that we talked about back in chapter 2 but what oh it doesn't have any of this or it has a lot of this okay and we can picture that why because we are talking about the pimped-out zone about the general I sell all right so what are the three main parts of a cell okay the three general parts are okay this outer white thing here separating the inside of our cell from the outside of salt we call this the plasma membrane okay the nucleus this large purple thing here okay and then everything else inside the cell except the nucleus right so the yellow fluid okay this purple stuff this green stuff this reddish orange stuff everything inside the cell except the nucleus we call that cytoplasm okay so generally speaking you have a plasma membrane okay a nucleus and everything else inside the souks at the nucleus we call cytoplasm okay so we're gonna start off okay checking them off one by one okay and we're gonna start off with something called the plasma membrane okay so the plasma membrane does what well it separates the inside of the cell from the outside of the cell okay it separates the intracellular inside from the extracellular outside compartments okay so if you think of the cell is the basic unit of all life well then it separates what it separates the living from the nonliving all right so if the cell is a living thing won't then the insides alive and then the outside is not alive so if we draw something okay on our pseudo white board and something that looks like this right so let's say here is a cell and there's the nucleus well then we consider it inside the solid this is what we call intracellular well then we can have another cell over here so here's another cell okay and there's the nucleus well then inside the cell would be considered also intra cellular so that's alive and that's alive okay so what's this stuff outside the cell well this is what we call the extra cellular space okay so what we drew in blue here this is our plasma membrane okay that separates the intracellular from the extra cellular all right now what is a plasma membrane made out of them well it's made of what we call a phospholipid bilayer phospholipid bilayer okay now a phospholipid represented by here yellow circle and these gray squiggly lines this is one phospholipid right here okay and in this picture you see many phospholipids coming together to make your plasma membrane okay so why do they call that a phospholipid bilayer because there's one layer phospholipids and then a second layer of phospholipids okay where the heads point out and point in and then the tails point towards one another all right so so in order to describe why it does a bilayer in order to describe why it ranges itself like this we have to know the chemical nature okay both inside and outside the cell okay so what kind of environment is out here outside what kind of environment is out here inside and also we have to know the chemical okay nature of our phospholipids so a phospholipid is composed of two parts okay the first part is this yellow part right here okay this is the phosphate group this is the head of our phospholipid okay and then coming off with that one phospholipid these gray squiggly lines here these represent what we call the fatty acid chains and there's two of them okay so here's my phosphate head here are my two fatty acid chains okay now the phosphate head is poor okay which means it likes water it is water-loving okay so this this yellow stuff part right here these are polar these phosphate heads are polar the tails on the other hand if you look at the chemical structure here that are made up of carbons and hydrogen's so here's my phosphate head which is polar and then here are my two fatty acid tails okay made up of carbon and hydrogen well these are nonpolar all right you guys remember hey your chemistry nonpolar means what well these do not like water these are hydrophobic so I have a hydrophilic head and I have two hydrophobic tails right so that still doesn't explain well why do I form two layers of phospholipids and why do they arrange themselves like I see in this figure right here well if we go to our pseudo whiteboard again all right the inside of our cells okay the inside of ourselves it is a very water like environment okay so inside of ourselves very water like very water like outside of ourselves okay it's also very water like so I have a water like environment inside intracellular E and have a water like environment outside extracellular ly all right so if I go over here okay and I start to draw a phospholipid okay plasma membrane okay so here is my okay polar head and here are my fatty acid tails okay would it work if I just had a single layer of phospholipids okay so let me just draw a single layer of phospholipids that look like this okay and if we recall again okay this is the head this is polar so this means what it likes water okay and these are the tails okay these are nonpolar okay in between what well they don't like water so if I had a single layer of phospholipids arranged like this would these polar heads have any issue interacting with the water like environment that's found in this extracellular space okay and the answer's no because these polar heads are polar they like water they're perfectly fine interacting with this water like at cellar space now are these fatty acid tails okay gonna have any issue interacting with the water like intracellular environment inside the cell and the answer is yes these tails do not like to hang around water okay so this would not be a stable membrane well what if I just flipped it then okay what if I put then okay the polar heads touching the intracellular part and then I had the the the fatty acid tails pointing outward okay is this going to work well the answer is no why because yes these polar heads now like interacting with the water like intracellular environment but these fatty acid tails now are not gonna want to interact with this outer okay water like it right this extracellular environment so to make this stable what do you do well you create two layers of phospholipids right where the outermost layer the polar heads are interacting with the outside extracellular environment and then you put a second layer of phospholipids okay where again the polar heads are interacting with the water like intracellular environment at the same time okay are these fatty acid tails okay I'm gonna like hang around these fatty acid tails okay yeah they're gonna be perfectly fine because these are nonpolar and these are nonpolar okay so when we think about your plasma membrane your cell membrane it is a phospholipid bilayer okay where the polar heads are pointing out okay polar heads okay and then the fatty acid tails are pointing inward okay into your plasma membrane all right now when people talk about plasma membranes okay they always think about right the phospholipids okay now plasma memories aren't just phospholipids it's not just the phospholipid bilayer okay in addition to the phospholipids you'll also find proteins embedded within the phospholipid bilayer okay you'll also find proteins embedded in that bilayer okay in actuality okay proteins make up half of the plasma membrane mass and so you kind of think of half phospholipids half proteins embedded within that phospholipid bilayer now one thing to note about these proteins is that they're not stuck okay so for example this protein here okay it's not like it's stuck in cement you can kind of think of these proteins as vessels in the ocean and ocean the phospholipids okay and what can happen is that this can float over here it can float all the way over here right so if if we kind of think about okay how these proteins are present within a cell membrane and if I come over here and let's say right now I have a protein and blood in my plasma membrane at the 12 o'clock position if I come back maybe an hour later maybe that protein is down here okay at the five o'clock position it drifted it floated okay in that ocean of phospholipids okay so these proteins aren't stuck okay they can actually drift and float around within our plasma membrane all right now in addition to being able to move move freely within our phospholipids okay we also have a variety of different proteins okay so example this protein is different from that protein for example right it's different from that protein so the word we use is that there's a mosaic of different proteins present within our plasma membranes so if we combine the two together okay the fact that they can drift and the fact that there's a variety of different proteins we say that our plasma membranes are a fluid mosaic right model of lipids and proteins all right it's a fluid mosaic okay model of lipids and proteins okay now there's different types of proteins okay present within our plasma membranes okay you can have proteins that are for example firmly embedded right for example here is a protein firmly embedded I actually pops out on one side of the plasma membrane that pops out on the other side of plasma membrane okay we would call this an integral membrane protein okay that's an integral membrane protein whereas proteins that are loosely associated with the plasma membrane right for example this one right here okay it's not firmly embedded loosely associated we call these peripheral membrane proteins okay they do not span the entire membrane but are loosely associated with other proteins or other phospholipids okay you can actually draw you can put another protein attached to that protein if you want to that would be considered an integral membrane protein right so you also have cholesterol present here okay five to 20 percent okay this makes now the inside your plasma membrane even more hydrophobic so water that's on one side of the membrane simply cannot pass through our phospholipid bilayer okay now you also see these green things coming off right these are carbohydrates these are and sugars so you can have the sugars attached to a protein we call that a glycoprotein or you can have the sugars attached to the lipids we would actually call these glycol lipids okay and these are kind of used for cell recognition okay the ability of your cell to be a recognizer for example okay so your immune system does what well it recognizes foreign cells well your immune system has to also have the ability to recognize cells that belong to you all right it's been kind of thinking these glycolipids okay as kind of cell recognition markers all right so what is the function right of a plasma membrane so where do you find it again well you find it separating the inside of the cell from the outside of the cell so if it something's got ever gonna come in contact with your cells the first thing it's going to come in contact with is the plasma membrane all right so what are some things you think about okay that can happen at the very surface of a cell so one thing okay is that outside and in between your cells okay again is this extracellular environment okay it's a very water like environment hey you can find out here fibers right there might be fibers running outside and in between your cells right these could be elastic fibers these can be collagen fibers these can be reticular fibers hey we call this part of what we call your extra cellular matrix okay it's called your ECM okay is your ECM alive no because it's outside in between yourselves right cells are alive so that cell and matrix consists of fibers okay by definition the tissues groups of cells closely associated that work together by a common function so what's holding these cells close enough so they could working together well they anchor themselves onto this matrix so if I go back here okay you can see here is an integral membrane protein embedded within our phospholipid bilayer and here are these fibers that are running outside and in between my cells and here I see myself grabbing on to one of these fibers and this cell grabbing onto the money fiber so it keeps the cells close to one another okay it's anchored by that matrix all right what's another function well how is siding in between yourselves you can have blood vessels right so if I put a blood vessel out here okay what travels in your blood pretty much everything right okay so let's say there's a hormone okay that gets filtered out of your blood okay so I'll push that hormone out so now that hormone is in this water like environment right what's gonna make it possible for let's say this is cell a okay and this is cell be okay which one of these two cells could respond to that hormone well in order for it to respond that cell has to have a receptor on its surface okay so let's say here okay this cell has a receptor that's gonna receive something that's shaped like a triangle hey this one over here this is gonna have a receptor that's gonna receive something shaped like a circle so which one of these two a or b is the target cell for this triangular hormone well it's gonna be a okay because a has the proper receptor for that hormone okay so another function we can think about in terms of our plasma membrane is cell signaling okay that's another function another one is what transport so what else is carried in your blood okay you can have nutrients care in your blood so let's say this is for example right glucose okay so glucose gets filtered out of your blood okay so how am I getting a glucose okay across my phosphor loboteca can King glucose simply pass through a plasma membrane no so what has to be present okay you need now these channel proteins okay so if I put up a protein here okay that has a little tunnel well now glucose okay is able then to pass through that tunnel okay and enter myself okay so you actually can see a better picture of that here okay labeled D we see that okay if I want to get something into my cell or out of my cell well then you need to use okay these channel proteins okay which are part of your plasma membrane again or you can join cells together or this idea of these glycoproteins gate pertaining to cell to cell recognition okay now up here these are G proteins we'll talk about this more in in Physiology all right now if someone to ask you what are the function cells you wouldn't be wrong saying any of these would be the function of a plasma membrane okay so if someone asked you what the function of plasma membrane is you can say oh it attaches this the cell to the cytoskeleton its and plasma membranes are involved in cell signaling plasma membranes are evolved and transport so forth and so on but kind of the main function of a plasma membrane is what it acts as a selectively permeable membrane okay your plasma membranes act as a selectively permeable membrane so what does that mean selectively permeable permeable means allow to pass right so if I had the words selectively to that what does that mean well not everything passes right it discriminates right whether you can pass in or out of the cell depending on properties all right so one analogy I can probably be give is let's say okay there's a there's a brand new cake club that opens up all right back in the day when I used to do that kind of thing right I wouldn't show up until the very end okay you gotta be that's how you did it don't come you know you don't go the right when it opens and you go in there I'm right on top of a clock or something I that midnight okay so the plasma membrane is kind of like the bouncer of that Club okay and what's the job of the bouncer okay or the person at the door okay is to regulate who comes into that Club okay who gets kicked out of that Club so if I'm showing up at midnight okay with all my boys it's like me and like five other dudes okay and we're rolling deep right yeah yeah midnight it's already packed all right what's probably not gonna happen well we're probably not gonna get in why because it's packed and it's all dudes and then right behind us are six girls right and what happens what possibly lets them in and I'm looking at my boy just happen here you didn't let us in but you're gonna let them in what's going on here selectively permeable all right that's the kind of the same thing as applies a membrane okay you're not gonna let everything in or out of the cell you're gonna be selectively permeable what comes in or out of the cell so what are some properties of those substances that's gonna dictate whether or not they're gonna be able to pass through the plasma membrane well size can be one thing okay so if I go back to this picture here okay these are probably very small things that can pass through that little tiny port to get into the cell if I now draw something five times the size of these things it's not gonna pass through here all right so size can be a limiting factor okay what's another factor okay it can be what well it can probably be charged chemical property if I'm dealing something that's very small and uncharged I pop you can pass right through the plasma membrane but if I'm talking about glucose glucose is not going to pass right through a plasma membrane right so when I think about what's the kind of the things that limit whether something can enter XSL is gonna be sighs it's gonna be charged all right all right so questions for you guys okay what is diffusion what is osmosis okay what is diffusion what is osmosis well diffusion Gate results from the movement of particles could be ions it can be something that glucose can even water right diffusion is the movement of a particle okay a substance from high concentration to low concentration all right so if I see this picture here right here on one side of this filter this is the filter in these little tiny pores all right this side of the filter high concentration of a solution okay on this side of the filter low concentration of a solution well what's gonna happen well these molecules here whatever they are these these little yellow spheres they're gonna move from high to low okay so you're gonna see a net movement of these yellow balls here going from the left to the right all right now very important this is a passive process okay meaning that I don't need to blow really hard or shake this and okay or stir it it's gonna happen on its own is they passed that process no input of energy is required for diffusion to occur it will happen on its own okay now eventually what's gonna happen is that the concentration of the solution on both sides of that filter are gonna be equal right which means that there's no more net movement of these yellow spheres from left to right okay you're gonna reach what's called equal Ehrman what does that mean though is does that mean that this yellow sphere is stuck here forever okay no it means this can still go this way but most likely then you're gonna get an equal movement of a molecule in the opposite direction you reach what we call equilibrium at that point okay now before we move on with diffusion and osmosis right we have to define what a solution is okay so what is a solution well the solution has two different parts okay and what are the two different parts of a solution what are the two different parts of a solution okay well the first part we can't is a solute okay the second part of a solution is the salt event today so we have a solute solute I'm sorry and a solvent okay what's the difference between the solute and the solvent well the solute is what gets dissolved okay the solvent is what does in the dissolving right so if I had for example okay a pitcher of kool-aid all right is that a solution yeah because it has a solute and has a solvent okay so what's the solute of kool-aid well what's what gets dissolved well the the the red powder right the sugar so for the solute we're talking about okay the red sugar powder that's what gets dissolved well what's the solvent portion of kool-aid well then the solvent portion is water okay it's what does the dissolving water is a very powerful solvent okay so a solution consists of two things solute and solvent so if I talk about okay let's say okay look kool-aid solution that's very concentrated right concentrated solution of kool-aid what does that mean okay which one's higher the solute or the solvent and what would it taste like well it tastes very sweet right something was very concentrated kool-aid okay it'd be very sweet why because you have a lot more solute okay and not so much solvent water you put way too much of the sugar powder okay and not enough water right or if you had a daily diluted solution okay of kool-aid what does diluted mean well he's gonna taste more like kool-aid or more like water it's gonna taste more like water why because you put way too much water solvent okay then the sugar the solute right so if you remember these things concentrating means solute is high solvent is low and dilute means that Solomon is high in solute is low it's gonna help you guys figure out the movement okay during diffusion or osmosis all right so let's go back to our to our PowerPoint here okay so again here concentrated solution diluted solution right so we're gonna go from high concentration to low concentration all right another type of diffusion is called facilitated diffusion all right so let's say these are glucose again right these green dots right okay glucose is high outside the cell glucose is low inside the cell so this is the extracellular fluid this is the cytoplasm right this is the intracellular side can glucose simply pass through the phospholipid bilayer okay it is the charged molecule can it go through here the answer is no because the second that glucose Peaks its head inside okay it's gonna see these hydrophobic tails like a heck no I'm not going in there okay this is like Indiana Jones here's the inside of the temple and Indiana Jones wants to get in Temple okay well one thing you know about Indiana Jones he doesn't not like okay snakes so he's gonna try to go this way he's gonna see lots of snakes go I'm not going that way okay he's gonna figure out another way to get into the cell to get into the temple all right so right here this is a channel protein this is an integral membrane protein that is shut that is closed so if you wanted to answer you can't it's shut off but let's say here is another channel protein where the channel is open okay so what happens now you're able then to diffuse from high concentration to low concentration so in the absence of this channel protein you would not be able to diffuse from high to low okay you just be stuck outside but the fact that there is a channel protein and allows you now to now go from high concentration to low concentration it means that you were facilitated you were helped okay so this type of diffusion facilitated diffusion requires specific transport proteins that act as selective corridors to get in or to get out of the cell all right now what a Barret one porn thing to note about these things as you learn this in Physiology that these transport proteins are very specific okay so for example if this was glucose this is a glucose transport protein okay it's not gonna let anything else pass through but glucose in many cases alright so facilitated diffusion requires the presence of these proteins let me ask you this question right is facilitated fusion a passive process or do you think it's gonna require energy okay so we define diffusion as what one would find it as a passive process no energy is required so it is facilitated diffusion a passive process the answer is yes its diffusion ii used the word diffusion it's a passive process okay the only reason why we say facilitate diffusion is because we needed the presence of this protein in order for it to occur okay so helps diffusion helped why because now we have the presence of this transport protein so I can make up a diffusion starwars diffusion you can ask me a question is starwars diffusion a passive process there's require energy I'm gonna say it's a passive process I don't know what star wars defeat it sounds cool it sounds really cool actually okay I don't know what it is though but I know it's a passive process because you said diffusion alright okay so moving on from diffusion okay we're gonna talk about diffusion of water specifically okay and the diffusion of water specifically okay we call osmosis okay and so more specifically osmosis is the diffusion of water across a selectively permeable membrane okay so water is a molecule right water again is a solvent so whenever people talk and think about solutions and diffusion okay they always think about the solute they always think about this all you going from high concentration to low concentration they never think about the solvent the water going from high concentration to low concentration all right so if I go back to this picture okay over here when we first describe what diffusion was all about right and if I draw on this okay I shouldn't want to drawn it okay I'll just I'll just I'll do it over here okay so if here is my membrane okay and this was our concentrated solution okay and this was our dilute solution okay and you guys this is what it means right okay the concentrated solution it had a lot more of the glucose on this side okay the dilute solution not so much glucose over here okay so if I look at this which way is glucose is gonna want to go well it's gonna want to go from high concentration to low concentration high concentration to low right so you're gonna get a net movement diffusion of the glucose from left to right okay and that's where people would leave it but the thing is though solutions not only have a solute they also have a solvent okay and the dilute solution has a higher solvent concentration okay so water is higher on this side it's lower over here so which way is water gonna go well water it now is gonna go in the opposite direction it will diffuse from high the dilute solution to low the concentrated solution alright so one thing you if you ever want to remember this water follow solute okay so look at the site it's really concentrated water always wants to go to that concentrated site okay so this diffusion of water from high to low is called osmosis okay so diffusion water across a selectively remember and that's what we drew here we drew a selectively permanent right here okay we call that osmosis all right so let's look at this YouTube experiment right here and we see that here is a diluted solution over here is a concentrated solution all right and separating the two solutions is a selectively permeable membrane all right now look at the pore size of our membrane okay and look compare it to the pore size of the sugar okay do you think the sugar can pass through that tiny pore okay well it can't right so here we're actually selecting on size we're not gonna able to allow sugar to pass through but water is small KDK water can pass through those tiny pores of our selectively permeable membrane okay and the answer is yes so we're gonna allow water to pass but we're not gonna allow the sugar to pass okay so what's the consequence of that now this is a concentrated solution this is that dilute solution so yes the sugar doesn't want to go to the luck but we're not gonna allow it because we're blocking in here okay water though can pass where is water more concentrated well this is the dilute solution okay this is the concentration okay water is gonna want to go from left to right so what is this can look like if I do this for an hour okay what is this gonna look like after an hour okay well I'll expect this to drop and this then to go up it's gonna look something that looks like this right so when is this gonna stop rising when what well when the concentration in both sides of the filter are now equal so water is now going equally to the left and also equally to the right right we've now reached what's called equilibrium all right so this is an example of osmosis we're showing you that water actually can also diffuse from a region of high concentration to a region of low concentration okay so why is that important for animal cells well it's important because okay we gotta make sure that we bathe our cells okay an environment that we don't cause ourselves to blow up we don't cause ourselves to it's to shrink okay we got to make sure the environment okay inside or outside ourselves is relatively the same so let me draw this here okay on our pseudo whiteboard in terms of what's going on on that slide okay so let's say okay we have a cell all right so here's our cell here okay I'm not gonna draw nucleus guys okay all I'm gonna draw is that inside the cell okay it has some sort of solute in here okay I'm dropping this green dots now we're gonna place our cell okay in different gate solutions so say in one solution okay here's our cell okay here's our solute okay and we're gonna put in a solution that has equal concentration of solute all right we're also going to put our cell in what well let's put it in a solution okay that is more concentrated in the inside of our cell so the entire cell has okay let's say two green dots the outsider saw okay let's put it three green dots now so what's a more concentrated solution and the third type of solution we're gonna place our selling okay we're gonna put in a solution okay that is more dilute compared to ourself okay so here is our cell here's our solute okay I'm put one green dot outside all right so what's gonna happen okay for example when I first put myself in this solution all right so let's do a little checklist here right so we'll compare the inside of her cell with the outside of ourselves okay so we'll do an inside versus outside okay so the inside is a solution there's a solute okay and there's a solvent okay if I put brackets around it guys this means concentration okay outside of myself has a solution there's a solute okay there's also a saw bent so where is the solute concentration higher okay inside my cell or outside of myself hey where is solute concentration higher inside myself or outside myself I'll do the same right two dots two dots okay so I'm putting equal in terms of solute okay where's solvent concentration higher right people always raise your hands they go outside the beaker right here all this there's more water out here and then inside the cell I'm not talking about volume guys I'm talking about concentration where is solvent concentrated where is water concentration higher okay they're equal right so basically I place myself in an environment that is equal right now this is our plasma membrane here guys right in black okay we're gonna make it selectively permeable okay we're not gonna allow the green sugars to pass but water can pass okay so which way is water gonna go okay given that I put myself in an equal solution well water is at equilibrium okay so water is gonna go into my cell at the same time water is been and then exit myself okay at the same rate so we call this solution guys okay where the the the concentration okay is equal inside amounts I saw inside and outside my cell we call this an isotonic solution and that's what we're striving for in our body okay we got to make sure our cells are bei the Knights of tonic solution so is my cell gonna shrink or is it gonna swell or is it gonna stay the same water is entering water is leaving okay so if you put your cells in isotonic solutions they're gonna stay the same okay all right so let's do a checklist for now here what if I put myself okay in a more concentrated solution right so I have inside I have outside right I have a solute concentration I have a salt vent concentration inside myself okay same thing outside my cell have a solute okay have a solvent so where is solute concentration higher okay I see three green dots I see - okay so solute concentration hires outside myself my solute concentration is lower inside myself right so another way you could have done this is you can say which one's dilute which one's concentrated well this is concentrated right here okay so what does it mean that outside is concentrated so I go back to this concentrated means concentrated means that the what the solute is high and the solvent is low right so if I go back here this is concentrate so solute is high okay solvent then is low okay inside is more dilute okay we did dilute me well dilute meant meant that the solute was low and the solvent is high so here the solute is low okay and now our solvent is high okay so again this is a selective remembering okay glucose cannot pass through but water can pass which ways water gonna go into my cell or out of myself if you place it in a more concentrated solution won't look at it again right you're going from a region of what a region of a high concentration inside my cell to region of low concentration outside my cell so what what is water gonna want to do okay water is gonna want to leave yourself alright so when you place your cells in a more concentrated solution that solution is what we say hypertonic to ourself okay and when you play cells and hypertonic solutions are they gonna swell are they gonna shrink or they gonna stay the same well they're gonna lose water so your cells you expect them to shrink okay all right so what happens guys if we put ourselves then in a dilute solution then right so here's inside my cell okay here's outside myself okay I have a salt judt concentration inside I have a solvent concentration inside same thing with outside I was so ute okay I have a saw vent right so which was more concentrated which one is more dilute okay the inside is more concentrated right then inside has a higher solute concentration which means that it's solvent concentration is low okay the outside is the dilute one which means what well its solvent is high a lot more water its solute is low alright so which way is water gonna want to go well if I look at that what's which way is water gonna want to go it's gonna want to go from a region of high concentration to a region of low concentration so water is gonna go from outside yourself inside yourself okay so when you place eight cells in what we call hypotonic solutions okay more dilute than the cell itself well is it gonna swell is it gonna shrink or is it gonna stay the same well it's gonna gain water it's going to swell okay so that's why we're talking about osmosis when we talk about the plasma membrane right and the reason for that is because you want to place your cells in this case a red blood cell you want to place them okay in isotonic solutions okay you don't want them to gain water so here are red blood cells placed in isotonic solutions you put them in hypertonic solutions they're gonna lose water they're gonna shrink okay do you think a red blood cells gonna function properly if it looks like this and the answer is no right okay what happens you can put in red blood cells in hypotonic solutions and they gain water well they're gonna swell if you put in an extremely hypotonic solution what can possibly happen they can blow up all right taking it the internal use for that they can lyse in that case all right so this regulation of water there's water balance animal cells we call this Osmel regulation all right all right this next part of your plasma membrane okay is this idea well how do I get large things into my cell or out of myself or how do I get lots of things into my cell or out of my cell at one time well you're gonna use something called vesicular or bulk membrane transport all right now bringing stuff in we call that endocytosis getting stuff out we're gonna call that exocytosis so let's start off with the first part here let's start talking about endocytosis let's talk about bringing stuff in to our cell all right so here okay when you go to Costco what do you do well you buy things in bulk right you're not gonna walk out with just eight rolls of toilet paper you're gonna walk out with like 32 rolls of toilet paper right so here we're showing you getting lots of these green things into our cell wall at one time alright so there's actually three different forms of endocytosis okay the first form is called phagocytosis which means cellular eating alright another one is called pinocytosis which means cellular drinking now the first two they're very general if you're in their general vicinity of an endocytosis involving phagocytosis or endocytosis you're you're coming into the cell even though you didn't mean to get into the cell if you're in the general area with one and two you're getting into the song okay now three is a more specific form of bringing things into a cell and it involves receptors that are embedded within the plasma membrane okay and involves whatever this is binding to that receptor and whenever we bind to the receptor then we bring that thing into ourselves okay so this one's very specific receptor mediated endocytosis all right so start first about phagocytosis means cellular eating all right so let's say here is my phospholipid bilayer and what you can see guys your cells they don't have to keep you know a nice spherical shape we actually can now change the shape of our plasma membrane okay and we start to form are these little finger like extensions here okay and these little finger like sergey's foot like extensions as we call these pseudo pots okay so you can see a pseudo pod here in a pseudo pod here in the pseudo pot here alright and what happens is that the two come together okay this pseudo pod will fuse with that pseudopod and what it does it creates this vesicle that then brings in whatever this red structure is okay but the fact that these fuse together they make sure that the plasma membrane is always continuous and no point do you create a gaping hole in yourself okay so picture this moving this way picture this pseudopod moving that way and when they come together they fuse okay and when they fuse you form a vesicle okay that contains whatever EU factors are toast at the same time you reform the plasma membrane okay so that's how white blood cells for example that's how white blood cells okay eat things that don't belong in your body okay so this vesicle now that's found in the cytoplasm of that cell we call this vesicle it is known as a fat goes on all right now if cells can eat they can also drink right so what type of environment do we find outside ourselves remember it's a water like environment okay it's a very water like okay extracellular environment the water we call interstitial fluid so if there's something dissolved in that fluid well if I drink the fluid well whatever will is dissolved in it is now inside the cell so here's my plasma membrane here's my phospholipid bilayer and now all I'm gonna do now is I'm just gonna imagine a and when you invention ate okay what happens is that this and that will fuse and when these fuse will one you reform the plasma membrane and two you create what's called a Pino site on of ethical containing the fluid that was outside the cell you essentially you drink the fluid you drank that extracellular interstitial fluid okay so we call this Pino cytosis and then the last one okay the two first two were very gentle if I found in that general area here I'm getting in all right this one here requires receptors so here's a liver cell here in yellow okay is my plasma membrane right there and these purple things represent receptors okay now here's a cholesterol in a low-density lipoprotein particle an LDL particle okay and inside okay its cholesterol outside you guys can see hey are these proteins okay embedded within this phospholipid code so when that protein binds to that receptor this is what actually then triggers endocytosis to occur okay without those proteins or without receptor this is not getting into the liver cell okay but once that protein binds the receptor endocytosis occurs and now that LDL particle is contained within a vesicle inside of my liver cell okay so the liver actually has 500 different property of functions one of the functions of the liver cell is to lower your cholesterol levels okay what would happen guys if there was a such thing as a disease okay where the liver cell doesn't make these receptor proteins what's going to happen to that person can they have receptor-mediated endocytosis and the answer is no so describe the cholesterol levels of that person who has no receptors on the surface of the liver cell higher low well they're gonna have high cholesterol levels okay we're actually gonna see that okay when we do the genetics packet there's a disease called hypercholesterolemia okay where individuals okay produce a reduced amount of receptors on their liver cell or in some cases a very severe case don't produce any receptors for cholesterol on the surface of their liver cells all right so that's endocytosis right so this next one is exocytosis so instead of bringing things into the cell okay we're gonna bring things out of the cell in bulk all right so here's the cytoplasm down here this is intracellular this is outside the cell this is extracellular out here okay so here are these green dots that I want to bring out of myself okay and to do that you need to put it in a vesicle alright so here is a phospholipid okay bilayer and inside that is the things I want to secrete okay now embedded in that are these proteins we call these ones V snares or vesicle snares okay these are the ones embedded within the membrane of my vesicle now embedded in the membrane of my plasma membrane are these these light purple things here these are called plasma membrane snares okay they're also known as a T snares or target snares right and so what happens is when this vesicle gets close to the surface of the plasma membrane the vesicle snares they start to intertwine with the target snare so it looks like this okay and what that does it brings the vesicle close to the cytoplasmic side of the plasma membrane well these are phospholipids and those are phospholipids what can phospholipids do when they come close to another well they confuse okay so the phospholipids of my plasma membrane fuse with the phospholipids of my vesicle so what happens well it creates a pore okay so whatever it was inside my vesicle now is exocytosed out of my cell okay on top of that the vesicles that were amines mean the phospholipids that were once part of my vesicle okay those phospholipids now will become part of my plasma membrane okay so here we see an example of what's called a goblet cell you guys will see goblet cells later on in the term okay and what we're exercising is a glycoprotein called mucin okay and when mucin mixes with water well then you produce something called mucus all right okay so we'll stop there for this particular lecture guys right and then we'll pick up with part two of this okay cell packet will actually start with the cytoplasm on the next lecture all right I'll see you guys on the next one bye