all right so now we will finish up our chapter three uh topic with the second PowerPoint here uh this uh is going to look at the um structures of both the proarotic cells which we certainly are going to focus on uh in microbiology but also uh ukareotic uh cell structure and function as well so the first thing we want to understand when we are uh talking about the bacterial or proaryotic world is that these cells are very simple in their uh morphology their shape um what we see here or we have terms to describe the shapes of uh proarotic cells um the first term uh is coxus or coxi c o cci for the plural uh coxus means circular spherical uh then we have a rod is the term for cylindrical uh vibrio is the term for curved rod um I I like to uh have you guys just imagine uh the vshape when you think vibrio so vibrio V-shaped like a curved rod okay so put your V's together there spiralum is spiral shaped so we see a cell that's a little wavy and then finally our last term here pleomorphic um is a term for uh not having a defined cell shape we'll see uh one genus of bacterium that is pleomorphic because it does not have a cell wall and therefore will change in its shape um so whenever we describe uh a bacterial species we'll always talk about the shape of the cell because this is something that is defined with each of the species so um for example as we talk about strep or staff we'll refer to them as being cooxy um cells that are spherical in shape when we talk about ecoli salmonella things like that they will be rods um so we will um always refer to the cell shape as part of the overall description of a bacterial species but what's uh important to understand too is that uh in the bacterial world uh the cells are sometimes going to associate with one another and form these groupings that are characteristic for particular species um the groupings we see include the first one pairs um and we see uh cooxy uh the spherical shaped cells will arrange themselves sometimes in pairs with the example of neria gorrhea um so what we're saying here is that if you were to look at the uh bacterium that's the causitive organism of the disease gorrhea um we would see in the microscope that the cells would be circular in shape and they would be paired up with one another so coox eye pairs um one way that you can uh think about this uh because one of the things you're going to have to do for this first exam is uh match um bacterial species to their morphology um one thing to help you remember this is that remember that ganorrhea is a sexually transmitted disease and these cells that cause this are in coxy pairs which you don't have to be too creative to imagine what piece of the anatomy we might be referring to is sexually transmitted disease anyway okay balls we're talking about balls anyway uh so uh so keep that in mind uh when you see um niceria which is uh the genus we'll see another uh organism that uh is of the same genus it will also be cooxy pairs um but when you see niceria ganori then gori a sexually transmitted disease cooxy pairs okay um next we have chains uh we see that in the case of coxide it can form chain so we see a chain of circular cells um the example here uh strepus uh more specifically uh we'll see for this first lecture exam the species uh strepcus pioynes the causitive organism of strep throat um what I like to associate with that strep throat you know think of how this looks like a pearl necklace that you'd wear around your neck strep throat right um then we have coox eye clusters uh so we see these circular cells clustering um so forming these associations where they're grouped as a bunch and uh we see an example of a a genus that does this a staflocus and we'll see this is the case for staff arius and staff epidermis um both um uh examples of the stafloccus genus um having the cells forming these cooxy clusters um so this helps us in identifying uh an organism um you know going back to uh the previous part of the chapter we said looking at a a cell is not generally going to be enough for us to identify the organism uh but let's say we have a person who um has the symptoms of strep throat you know sore throat enlarged uh tonsils patches on the tonsils all that stuff and then we see it the bacterial sample that we get from the throat has grandpositive coxide chains that might be enough for us to conclude that those cells are strep piogenes because now we have the um Graham reaction that they're gram positive we have the cell shape and we have the grouping along with the symptoms of the patient all that together can um help us draw that conclusion that that organism is very likely um strep pioynes the causitive organism of strep throat now uh groupings are not going to be the only um multisellular um uh structure that bacterial or proarotic cells can form um our next structure here we see the um group of bact of bacterial cells called the mixobacteria um will actually form a multisellular structure called a fruing body in times when the environment is poor um so uh we see the phrase misery loves company as a way to remind you that when the environment is good the cells are happy to spread out and thrive within the environment uh but when the environment is poor uh and the cells are under stress and struggling for survival what they'll do is uh join together and form this multisellular structure uh that uh protects the cells within it and helps sustain the population as a whole okay so the fruing body of the mixo bacteria is a multisellular structure made from cells that are individually uh organisms of their own but the the cells of the same species join together and work together to form this multisellular structure for the population's survival similarly we have uh commonly with environmental bacteria um the ability of the uh cells to form what's called a biofilm and a biofilm is going to be where um cells join together and they produce uh a material called a slime layer that allows for them to adhere to surfaces so think of this like uh you know anything that you would find in the environment like let's say you had a found a metal pipe that was laying in a river um you you know that on the outer surface and the inner surfaces if you were to touch it after it's been there for you know uh months or years that it would be you know slimy in texture it would have this this material on its surfaces um and what that is is a um a a carbohydrate complex that's produced by the bacteria on the surfaces and the bacteria are working together to basically uh glue the whole community to that smooth surface so you know this this smooth surface um with running water coming across it would not be something that the bacteria could stay on for very long uh without being washed away so instead the bacterial population produces this uh secretion this slime layer that helps glue them all down as a population to that surface so we have the slime layer uh oops I didn't mean that one uh we have the slime layer um right here um allowing for this population of cells to stick to this smooth surface and and thrive on this surface that other that otherwise would be um the uh would be difficult for the cells to connect with uh so um we find that in we see the examples of you know rocks and streams the gunk that forms in in uh kitchen drains uh scum in toilet bowls and then also the plaque on your teeth think about your teeth they are smooth they're bathed in saliva we are constantly washing them as we drink beverages and the only way the bacteria are going to be able to stay on that surface is if they glue themselves as a community to the surface and form a biofilm okay so we're going to go and look more closely at the structure of bacterial cells and proarotic cells in general so remember the proarotes included the archi and the bacteria so um but in this course we'll certainly be emphasizing bacteria um but this is going to be true for proarotic cells as a whole proarotic cells are going to be very simple in their structure we learned before that it meant that it did not have a true nucleus and so we see a cell that does not have uh a membrane around its uh DNA we see that has no internal cell membranes at all um so it's going to be much simpler in its structure than ukareotic cells that we studied as we learned about the the human body in um anatomy and physiology so the uh proarotic cell structure uh is uh something we're going to learn from the outside in we're going to look at the structures around the outer surface and then work our way into the cell and we're going to begin with the structures that extend from the surface of the cell the filamentous appendages the first of these is the fleella we see a fleella is a long protein structure that is going to work like a propeller to uh push the uh cell through its environment so we see these fugella these long structures coming out of the surface of the cell and as they whip around they will propel the bacterial cell through its environment okay so this is going to allow for bacteria to move uh if they have the fugella and uh in addition we see that in the case of this organism here helicoacttor pylori this is the causitive organism of our stomach and dadinal ulcers um this organism can use the fleella to drive itself through the protective mucus that coats our stomach and dadum and allows for it to drive through that mucus and then uh uh affect our epithelial cells in that portion of the digestive system so we don't have to worry about most of the bacterial cells that we're accidentally eating because you know they're not going to have that fleella and that ability to power their way through our protective mucus we see here that the uh fleella are produced by a protein called fleellin so great name for it easy protein to remember in bacteria they use fleellin to make the fleella and we see the fleell is anchored to the cytoplasmic membrane and cell wall so it is a structure that is down in the cell membrane as well as in the cell wall it needs to be connected to the cell's membrane uh because it needs to have that connection to the cell if it's going to be propelling it so it can't just be a structure that's just sitting on the surface we see here that the the protein structure is built all the way down into that plasma membrane so that as it's whipping around it is propelling the cell which is of course defined by its uh phospholipid plasma membrane now we have some terminology that comes along with the function of fleella um so as the fugella uh propel the cell uh our term for the movement of a cell is taxis okay taxis means either movement toward or away from and then we will put a prefix on it to describe a stimulus the thing that is determining um how the cell is moving so let's look at the prefixes that we can put in front of taxis chemo chemicals so movement toward or away from chemicals uh chemotaxis was something that we learned about uh in as um important with the immune response where immune cells had to follow chemicals to find and kill the bacterial infection they followed chemicals cheoaxis movement toward chemicals phototaxis uh light so movement toward or away from light arrow oxygen movement toward or away from environments that are rich in oxygen magneetto uh movement toward or away from uh magnetic fields and finally thermo uh heat so movement toward or away from heat or thermal energy okay and so um this uh taxis this movement remember is in response to some kind of environmental stimulus um and this is what's going to drive the activity of microorganisms uh that's summarized here for you um so ultimately when it comes to uh all those different forms of taxes there's always some kind of a stimulus that's that's a driving uh force for the um you know actions of the proarotes okay our next structure that uh is going to project out of the um uh cell wall and outer structures of the cell are the pilli so a pillas is a hairlike structure pilly is going to be plural so hairlike structures um these are much shorter than the fleella so we see if this is a fleella you know this is um the you know the smaller pill and we have a couple of uh types of uh pill to consider the first is the fimrii fimrii uh is going to be needed for attachment of the cell to surfaces so these little hairs allow for the bacterial cells to stick to surfaces because they can be capped with a molecule called adhes so this is an adhesive protein that allows for the organism to stick to a surface so let's think about um bacteria that are going to be sticking to surfaces and how important the fimrii with adhes are going to be in the case of ecoli ecoli um certainly needs to position itself within the digestive tract that has a lot of movement um going on but ecoli is also a very common um source of urinary tract infections and if an organism is going to infect the urinary tract it has to hold on to the uh epithelial layer of the urethra and the urinary bladder to make sure that it isn't just washed away with the urine so the E.coli has these hairlike projections the fimrii that allow for it to attach to the inside of the urinary tract and work its way up as they are also useful in producing what's called this twitch motility slow jerking motions that just slowly move this um cell up the urethra and into the urinary bladder um so this is not as powerful and and dynamic as a fleella but still helps the cell move along and we see niceria donori doing the same thing having those same hairlike projections the fimrii that allow for it to be an infection of the urinary tract once again this is a sexually transmitted disease it's going to infect the uh male urethra that is constantly being rinsed with urine and it so it needs these hairs to hold on so it's not washed away and if you're putting that all together we re uh recently referred to this organism as looking like the features of the male anatomy here but now we just added to it that they are hairy so the when you visualize niceria gorrhea think hairy balls all right and that will stick with you hopefully um and then you just need to name what that more scientifically you know hairy fimrii and then cooxy pairs we see the other feature of pilli is that they can work as sexy which allow for the bacterial cells to share DNA with other bacterial cells in what we will refer to as conjugation which is put in kind of simple terms um like bacterial sex so it's DNA transfer between uh bacterial cells which we will learn about in more detail uh in the second unit of the course now the uh next couple of features are going to be um like the pilli and uh and fleella um they're not um going to be found with every organism so these are unique to certain species um and each one of these uh adds um some kind of function to the to the cells um so our first um uh extra feature here is the capsule and capsules are made from polysaccharides so these are carbohydratebased structures i like to think of capsules as like the candy coat on an M&M okay so polysaccharide you know the the candy coats a sugar on the outside so think of it like that sugar coat uh around the bacterial cell so if we go back to this picture here um this is the bacterial cells plasma membrane in green and we see way outside of that is this thick red candy shell um and that is the protective capsule so capsules are um helpful in allowing for the cell to interact with its environment adhere to surfaces uh but another thing that they do is help to prevent the cell from being uh veetized from being consumed uh by other cells uh and when we relate this to human health uh this is going to uh uh resist the uh body's immune defense uh so as our immune cells try to eat these bacterial cells they're more resistant to being consumed and we see an organism that has a notable capsule is streptococcus pneumonia and we'll learn about later on in the course how it's actually the capsule of this bacterium that triggers um the uh individual to become diseased by the infection next we have the slime layer again we mentioned that a slime layer is produced by cells in order to adhere the population to a smooth surface we have an example is the strepcockus mutans which is bacterial species that uh uh develops the dental plaques and uh and then we'll learn that the result of this uh bacterial growth in the plaque is that it will eventually also de develop um cavities in the tooth as we work our way inward now um we have the the next structure that uh is just so critical to the bacterial cell uh it is the cell wall so the cell wall uh keep in mind again we have come in from these outer structures we have the fleella the pill we have the capsule remember not every cell is going to have any or all of these features um but now we are into this yellow layer here the cell wall that is built around the cell's uh plasma membrane and the cell wall is really the defining feature of bacterial cells uh we see here it is a rigid structure determines the shape of the cell so the reason why EC coli is a rod and uh strep is a coxus is because of the cell wall that they create uh so the wall determines the shape because the wall is that rigid thing that is not going to be changed by uh environmental factors the cell wall holds the cell together and prevents it from bursting we will talk later on in this lecture about osmotic bursting and how um if water goes into a cell it can cause a cell to swell up and explode we saw that in uh AMP with red blood cells that if you put them in hypotonic solution they can burst well if the cell has a wall built around it that wall prevents the cell from swelling to the point of bursting and bacterial cells will use this protein we learned about in the first chapter of the course pepidoglycan peptoglycan was unique to bacteria and we will see how the pepidoglycan is built into the bacterial cell walls in a moment while we're on the topic of the importance of the cell wall we do have the example here of a bacterial uh genus and species that does not have a cell wall so myopplasma pneumonia is an organism that um does not produce the bacterial cell wall that we're used to um it is still a bacterial cell uh it just is one that um in its evolution lost the ability to make the pepidoglycan cell wall and so now it no longer can do this but it comes uh it's a descendant of bacterial cells that could and so without the cell wall it um it is pleomorphic it doesn't have a defined shape anymore since it doesn't have a wall to hold its shape and we see that myopplasma um has a solution to uh the stress of osmosis uh and that is the use of this molecule steriles that um provide rigidity to the plasma membrane so they're um not as at that great risk of um of bursting due to an influx of water so we got that unique bacterium to consider there uh that lacks a cell wall um we're going to compare the two types of cell walls here uh we have a gram positive cell wall and a gram negative cell wall and let's start by looking at them visually the grandpositive cell wall is what we see here what you guys should get out of this when you think of a grandpositive cell wall think lots of pepidoglycan okay so you hear gram positive you go lots of pepidoglycan comparing that to the gram negative cell wall we see the gram negative cell wall is more complex it has a little bit of pepoglycan but then it also has a layer of lipopolysaccharides so a combination of carbohydrate and lipid structure right here um so this is more complicated than the grandpositive cell wall you guys don't have to get overwhelmed with the information in this table um you know gram positive thick layer of pepidoglycan gram negative thin layer great if you know that you're doing awesome um we do see there are differences in the um overall structures here uh the gram positive does not use the lipopolysaccharides the gram negative does we see the lipopolysaccharides um do have significance to the gram negative cell um they can be responsible for um the uh difficulties that we face with bacterial infections um including causing tissue damage within the uh the human body um but overall um what we see is uh a list of things that are shown for you here but what I want you to come away with again gram positive thick layer of pepidoglycan gram negative thin layer the other thing you absolutely want to come away with here um is at the bottom know this today and for the rest of the semester be able to list these four genuses um without hesitation our grandpositive um bacterium fall in these four genuses that we're going to talk about lots through this course they're they're not the only grandpositive organisms but when it comes to this course uh we're going to talk about um almost entirely um just these four grandpositive organisms um and then every other organism that we're going to talk about is going to be gram negative or the myopplasma or acidfast something else but um if you know these four it's going to make your life so much easier the first two basillus and claustrdium are also the two organisms that make endospores so if you know those two facts about them when you hear uh me or somebody say basillus or claustrdium you should immediately go grandpositive endospor if you are doing that this will make you much more successful in this course likewise the other two grandpositive organisms stafloccus and streptocous are two S's the two really most common bacteria that I'm pretty sure everyone knew before taking this course staff and strep if you put those in this group we've got four organisms basilus claustrdium stafloccus and streptoccus that are all gram positive and um and then if I say something that is not those organisms so when I say klebella well it's not one of those four so what is it well it's going to be gram negative you know if I say salmonella it's not one of these four so what is it it's gram negative you'll already know what organisms are gram negative by knowing that these four are gram positive okay so that's why under gram negative it says pretty much every other bacterium we'll discuss with the exceptions of the acidfast and organisms and mopplasma which are just two genuses that we'll learn we're going to take a moment here and explain why the gram positive cells turned that dark purple with the staining method that we saw in the first part of this chapter and the gram negative cells ended up not purple it's because the crystal violet stain stains the uh pepidoglycan and we see here the grandpositive cell has more pepidoglycan and therefore holds more crystal violet stain so when you decolorize these two cells at the same time this one will lose that purple stain faster than this one and that's how we ended up with gram positive cells looking purple and gram negative cells looking pink so we'll take this second here to throw out a staff joke while we're thinking about a gram positive cells and we will move on with our discussion of the cell walls and the differences in their behavior first of all we see the antibiotic penicellin penicellin works by blocking pepidoglycan synthesis so penicellin is an antibiotic that prevents bacterial cells from making their cell walls because cell walls use pepidoglycan so if you block its synthesis you stop the bacterial cells from making the cell wall that is critical to their function we see that in general penicellin is going to be more effective against gram positive bacteria than it is to gram negative bacteria since gram positive bacteria are more reliant on making large quantities of pepidoglycan then we see lysosyme uh lysosyme was mentioned back in we learned about this as an enzyme that we produce in our body's solutions including tears and saliva and we use this enzyme to break down pepidoglycan peptoly uh breakdown is uh going to allow for us then to uh combat the growth of bacteria uh in places like for example the mouth um so the lysosyme is used to combat bacterial growth by destroying the cell wall but do make sure you understand the difference between these two penicellin did not destroy pepidoglycan it prevented it from being made where lysosyme destroyed pepidoglycan so two different things this one destroys what's already been made this one prevents it from being made both of them targeting pepidoglycan and therefore the cell wall of bacteria okay so we move in now to the cell's plasma membrane plasma membrane is something that you learn about in every biology class because this is the basis of how a cell is created all cells have a plasma membrane plasma membranes are made from the phospholipid billayer uh we saw that fluid mosaic model in the previous uh chapter um the plasma membrane is a selectively permeable membrane meaning that it can control uh the movement of some materials it can control uh certain materials will go into or out of the cell it doesn't have control over everything but it does have control over uh many molecules um what freely moves across the membrane is water gas and small hydrophobic molecules but then uh the things that are hydrophilic uh so uh charged and polar molecules and then also larger molecules um are going to be unable to just pass through the membrane without assistance in the case of the bacterial cells um they are going to need the plasma membrane to be the site of the electron transport chain which is uh needed for ATP production um hopefully you remember the electron transport chain uh uh as part of ATP production in um human cells we learned that this happened in the mitochondria and that it happened in the inner membrane of the mitochondria well it required proteins embedded in a membrane to do this the only membrane that a bacterial cell has is its outer plasma membrane so the outer plasma membrane is the only place where you can put proteins that can do the electron transport process and finally the plasma membrane is going to be the site of secretion uh so we will learn about how bacterial cells will secrete enzymes uh for example in order to uh manipulate things in their environment they so this membrane needs to have that ability to release material from inside the cell to outside of the cell so we see the structure here the phospholipid billayer embedded with proteins the proteins can work as channels the proteins can work as enzymes the proteins can work to drive things like the electron transport chain for ATP production this summarizes what molecules can go um pass through the phospholipid billayer remember that uh gases small hydrophobic molecules and water can all just go right through this membrane so it is permeable but we said it is selectively permeable because not all molecules can pass through it we see here that sugars ions amino acids ATP macroolelecules so large molecules none of these will be able to pass through this membrane because that membrane is hydrophobic and since it's hydrophobic it's going to repel all of the things that have charges or polarity this reinforces that water moves freely into and out of cells and uh that's we have the additional structure the aquaporin that reinforces this free movement of water so let's do a quick recap on the movement of uh molecules into and out of a cell um by remembering the uh types of movements through a membrane we have um the first two that we'll talk about are going to be um simple diffusion and facilitated diffusion so diffusion was the movement of molecules from an area of high concentration to an area of low concentration and so what I like to do is have us imagine a membrane that separates two solutions solution A and solution B in solution A we have more sodium than we have in solution B everything that is white is water okay so solution B is all water solution A is water with sodium floating around in it and right here is a permeable membrane so this membrane is separating A from B but it does let sodium go through it it's permeable if we give this time the sodium molecules are moving freely around in this water and can pass through this membrane so these sodium molecules will eventually spread out to the point that a couple of these sodium will end up on this side and a couple will be on the other side and the overall effect here is that the sodium has spread out evenly this is simple diffusion this is what we see when we make tea with tea you put uh you know we put the a mix of molecules that have color and flavor and all that stuff into water and those molecules naturally spread out and they spread out evenly okay so you don't have a a cup of tea where the top of the cup of tea is like water and the bottom is dark brown they're spread out evenly um your can of Coca-Cola is evenly um distributing all of the colors and flavors that is diffusion so diffusion the solute the molecules floating around in the water spread out and go from where there is more to where there is less of that solute that is simple diffusion building on this we said that ions like sodium would not be able to go through a cell's plasma membrane it was selectively permeable so to make this more like a cell's plasma membrane what we're doing here is just showing that sodium is only able to pass through ion channels so making this look like a cell membrane we see that the sodium doesn't just go through the plasma membrane it has to go through the ion channels in this case our term for this process is facilitated diffusion facilitated diffusion uh is the movement of uh is the movement of the solute um through a channel so facilitated diffusion movement of the molecules from high concentration to low concentration through a channel whereas simple diffusion did not require a channel and actually doesn't even require a membrane civil diffusion is just molecules spreading out in space okay osmosis is the movement of uh water across uh a membrane in this scenario here uh what we're going to do is clear this and imagine a scenario where the membrane just like the cell's plasma membrane is not permeable to sodium so the sodium is on this side uh and we have no sodium on the other side uh so this side is water and sodium this side is all water this membrane is only permeable to water just like the cell membrane the sodium can't pass through it freely uh but water can so the question here is in the case of water uh will water move across this membrane and if so where will it move to well there are more water molecules on this side than there are on this side and so what's going to happen is naturally water molecules are going to find themselves moving uh toward the side that has more solute so osmosis is can be described two ways it's the movement of water from an area of more water to an area of less water or the other way of describing this is the movement of water from an area of low solute to an area of high solute okay two ways of describing the same thing that's happening here water moves to the side that has more solute water moves from where there is more water to where there is less water where there's less water it's less because there is more solute so that is osmosis okay okay that's described for you where we see osmosis movement of water from high concentration to low concentration through a membrane in other words movement of water from high concentration of water to low concentration of water or like I just described moving from where there is uh less solute to where there's more solute our last form of movement across the membrane is active transport active transport is the only one that requires energy everything else that we've described so far happens naturally you put a teab bag into water and the tea molecules spread out all by themselves um osmosis water moves across the membrane all by itself but this last one here is active transport this is going to um require the use of energy because it's going to go against the natural movement of molecules in this case you would think that sodium would go from A into B uh but if these channels are built to only allow for sodium to go from B into A uh the sodium's going to stay in A but what can happen is these channels can use ATP to grab this sodium and pull it to the other side using energy using ATP active transport is the cell using energy to pull molecules across its membrane molecules that wouldn't have gone ac wouldn't have gone across the membrane on their own so this is working against the normal movement of molecules so we see here active transport uses ATP and it moves molecules from an area where there is a lower concentration of them to an area where there's a higher concentration of them and that's why it requires energy because it's working against the normal movements that we saw with diffusion okay so what we're going to discuss right now is what happens to a bacterial cell if we place it into um solutions with varying amounts of um solute in them hopefully these terms are familiar to you from uh study of uh um but we're going to explain them for you here um so um if we have a cell that we have placed first into hypotonic solution hypotonic solution means more water and less solute more water less solute more water and less solute than the inside of the cell that means the cell has less water more solute okay and what we learned is that uh the solute does not just freely go into and out of the cell but water does so if we put this um cell into hypotonic solution then where there is more water this water will go to where there is less water or remember water goes to the area with more solute so water is going to go into this cell and so the question is what's going to happen to this cell in A&P we learned that red blood cells are going to swell and burst when you put them into hypotonic solution but we are talking about bacteria now and we have to remember that bacteria have a cell wall the cell wall is going to hold their shape so what happens when you put a bacterial cell into uh uh hypotonic solution the answer to that question the answer to this question nothing what happens to a bacterial cell water's going to go into the cell but the cell's not going to swell because it it doesn't have room to swell so the answer to this is nothing no change to the cell but let's hop down and think about what happens if we put into hypotonic solution with lysosyme lysosyme was the enzyme that destroyed bacterial cell walls so if you put this cell into the uh solution with hypotonic solution with lysosyme if it does not have that protective cell wall then what's going to happen here is it doesn't have that structure to keep it from swelling and bursting so with no cell wall the cell will swell and burst right it's going to take on so much water it's going to swell and actually explode and you know break apart so our term for that what you want to write out is lis cell bursting the cell is going to swell and burst so that that is our answer for this scenario here hypotonic solution with lysosyme lis the cell will swell and birth now let's consider hypertonic solution hypertonic solution is going to be the opposite of everything we just described here hypertonic solution is um low water high solute so like salty water you know lots of salt not a lot of water so we have a cell now that is by comparison uh high water uh low solute by comparison to the hypertonic solution around it since we have more water inside the cell comparatively high water here that means that the water is going to go out of the cell and it would be easy for us then going back to talking about red blood cells we said that red blood cells shrunk when this happened um but remember the cell wall again if there's a cell wall does the bacteria shrink well what happens is the bacterial cell is going to um shrink inside of this wall but if I were to try to look at this bacteria what am I seeing when I look at a bacteria in a microscope well what I see is their cell wall i don't see anything inside of the cell wall i'm I'm seeing the outside structure so if this cell shrinks it still looks like it's the same size cell because the cell wall has not changed our term for this is plasmolyis plasmolyis the loss of cytoplasm the shrinking of the cell inside of its wall so plasmolyis is the is the answer that you should put right here hypertonic solution what happens to a bacterial cell it's placed in hypertonic solution plasmolyis but what about a hypertonic solution uh with lysosyme well a hypertonic solution with lysosyme uh now now you could actually say that the cell has truly shrunk uh because now you can actually see with the removal of the cell wall with the lysosyme eating that away uh we have a shrunken cell so that's what you could answer there uh a shrunken cell with no cell wall our final term is isotonic isotonic is when a solution is the same in the amount of solute in water as the inside of the cell isotonic solutions um are going to not have an effect on the inside of the cell the answer to that the isotonic solution is going to result in no change and this was something that we talked about in AMP when we talked about uh the importance of maintaining homeostasis is that you want to create environments that don't put a stress on the cells and those environments should be among other things isotonic have the same water and uh solute concentration inside the cell and outside the cell okay looking inside the bacterial cell this is where it gets very simple so proarotic cells very very simple internal structures they have a single chromosome the single chromosome is circular DNA instead of a a a linear DNA so our chromosomes are one long line of DNA where the bacterial chromosome loops around and connects to itself making a circle and we describe it as being in the nucleoid which means that it's um it's not in a nucleus it's just in an internal region um that's not a true nucleus so we see here the DNA is you know all bundled up in one spot that we call the nucleoid that is not surrounded by a membrane it is not a nucleus so the chromosome has the genetic information that's needed for the cell's survival all bacterial cells all proarotes are going to have a um chromosome um but the next piece of DNA here the plasmid is something that is optional some organisms will have plasmids plasmids we see are small sections of DNA about 1/100th to onetenth the size of the chromosome and this is genetic information that is not required for survival because as I just said not all bacterial cells will have plasmids um an example of something that's not required for survival antibiotic resistance um this is uh helpful genetic material but not all cells will have it we see that shown here this small piece of DNA that is separate from the chromosome that small piece of DNA is the plasmid it is extra DNA that once again is not essential for survival some bacterial cells will have it and we'll learn more about the importance of plasmids in the next unit of the course next we have the uh ribosomes uh ribosomes are the structures that make uh protein so ribosomes make protein all cells both proarotic and ukareotic will use ribosomes to make proteins what we see here is that even though we all have ribosomes um our ribosomes are not the same so bacterial ribosomes are described as 70s where our ribosomes are described as 80s long story short we all have ribosomes but they are not the same as the you know the ribosomes of bacteria are not the same as ukarotes and they're not the same as archa so we'll actually see that um those three groups all have different distinguishable ribosomes we have a cytokeleton as a another structure to consider so proteins are going to help um organize the inside of the bacterial cell and then finally we have areas of gas and uh molecular storage within the cell but notice that they do not have membranes so they're deposits of material but they do not have any membrane that surrounds them because um bacterial cells proarotes do not have any internal membranes a final feature to consider with the um cell structure we learned about endospores we said that these were the dormant cells that were produced by these two genuses basillus and claustrdium remember basillus and clustrdium the only two genuses that we will learn about that make endospores and they are both gram positive endospores are dormant cells that are produced by the growing vegetative cell so we have the vegetative cell here and inside the endospore and endospores are special because we learned that they could survive first of all since they're dormant they can survive when the environment has no water or nutrients for them but in addition they survive the boiling process in Tindle's experiment the reason why they're able to survive boiling is because the DNA in their core is protected by this molecule dipolinic acid so diplolenic acid in combination with calcium forms a protective coat around the DNA that prevents the DNA from denaturing when the cell is boiled so we see that the protected endospore actually germinates it wakes up and starts growing after it's exposed to the heat that caused that outer uh protective coat to u break open and allow for water to enter the cell and that activates it to become a vegetative growing cell the cell actually survives under these very extreme environments that would have otherwise killed any normal vegetative growing cell now we'll take a moment to talk about ukarotic cell structure this is a review of uh topics that are covered in uh&p so I I am going to move through this fairly quickly um hopefully you guys remember these structures um and if you didn't cover an am you should have covered it in let's say like a principles of biology or something so hopefully all these structures um that are unique to the ukareotes um are something that you recall um so the ukareotic cell is much more complicated than the proaryotic cell instead of just uh um DNA and ribosomes inside we see the DNA is inside of the nuclear envelope we see the um complex areas of uh internal membranes creating the endopplasmic reticulum Golgi apparatus we see the uh mitochondria and lysosymes all sorts of structures built inside of this ukarotic cell um using internal plasma membranes to create them um so first of all the ukarotic plasma membrane what is more complex than the proarotic because it is able to go through um these uh activities that the proarot could not do um endoccytosis and exocytosis endoccytosis is where the cell draws material into it by uh bringing its plasma membrane inward the cytokeleton pulls the membrane inward the membrane pinches off and in doing so endo inside cytosis the cell the cell pulls uh molecules that were outside of it into the cell so endocytosis is a a cell's ability to draw material into it material that could not be brought in through just simple diffusion we see fagocytosis uh this is a term we've already used uh it's goes back to you know our earlier biology classes vagocytosis is the ability of a cell to consume another cell or large particulate matter it's the same process just replace these small molecules with a bacterial cell and in this case let's say a human white blood cell is able to gobble up and destroy a bacterial cell through the process of fagocytosis exocytosis is going to be in the opposite direction where we have uh internal membranes uh surrounding uh molecules that were created inside of the cell and those molecules can be shipped to and released to the outside of the cell exocytosis leaving the cell the cell is able to push um larger molecules and larger quantities of molecules out through this process exocytosis once again this is unique to ukarotes proarotes don't do this because their plasma membrane does not do this process of pinching off and and reforming like we see here um because uh we as we saw before um the the cells don't have any internal membrane structures ribosomes make proteins in the ukarotic cells just like the u proarotic cells the difference was they are 80s instead of 70s so they're different structure but still the same function just like the proarotic cell ukarotic cells need a cytokeleton they need proteins that create scaffolding and organize the uh internal structures within the cell uh so we see the cytokeleton using molecules like tubulin and actin to create that network of protein that holds everything in place within the cell the fleella and psyia um are going to be structures that stick out of the ukareotic cell the fleella in the ukarotic cell is bigger and more complex than the fugella in the proarote but it's the same overall concept a whip-like tail that propels the cell um it's not made from fleellin like it was in the bacterial cell instead it uses the microtubules and other proteins um so not the exact same thing as bacteria but it has the same general function and psyia are hairlike structures that stick out of the surface of ukarotic cells and that helps them increase their surface area and manipulate material around the cell the nucleus is uh what defined the ukareotic cell dna is surrounded by a membrane the nuclear envelope and creating that true nucleus mitochondria are the organels within ukarotic cells that create ATP so mitochondria generate ATP they're the powerhouse of the cell and in photosynthetic organisms including plants and algae um they will have an additional structure called the chloroplast so the site of photosynthesis that uh uses light energy to make organic compounds um so um we would not see the chloroplast in the animal kingdom but we see it in plants and algae now an interesting note about mitochondria and chloroplast these two uh uh organels are absolutely essential to ukareotic cell function and survival right the chloroplasts are what allow for plants and algae to do photosynthesis that's what makes all their organic compounds then we go and we eat those photosynthetic uh plants and algae and that's where we get our organic compounds and then both plants and humans and algae we all use the mitochondria to take organic compounds and create ATP from them so we are all dependent upon these organels to uh create um high energy molecules and then uh release the energy from those molecules well when we look at their structure what is amazing about these two uh organels is that they contain their own circular DNA and their own ribosomes that are 70s let's remember bacteria use circular DNA not the ukarotes and bacteria use 70S ribosomes uh we uh ukarotes use 80S ribosomes so in other words what we're saying is that mitochondria and chloroplasts have bacterial DNA and ribosomes inside of them because they evolved from bacterial cells okay let's explain that what do we mean by they evolved from bacterial cells well here is the history of it this is the um early uh ukareotic cell the cell that's on its way to becoming the ukarotic cells that we know of today here is the uh bacterial cell and the bacterial cell um remember what's inside of it inside of the bacterial cell we have um circular DNA and uh 70s ribosomes well when this gets gobbled up through endoccytosis and actually fagocytosis more specifically um let's see we're going to show you the faggoytosis taking place here um Oops uh so here is the uh cell gobbling up pulling in this bacterial cell so here it is the bacterial cell that has just been eaten right so bacterial cell that has just been eaten still containing of course its DNA and ribosomes right this is a mitochondria remember how a mitochondria had an outer membrane and an inner membrane the inner membrane was where ATP is generated through that uh the uh electron transport chain right that that it was part of that process of ATP generation remember what we said the bacterial plasma membrane was the site of the electron transport chain just like the inner membrane of the mitochondria is the site of the electron transport chain um so putting that all together the way that we as ukarotic organisms today have uh an organel that is responsible for making ATP for us is we basically captured uh bacterial cells in our evolutionary history and we forced them to make ATP for us okay so our cell by itself does not have the ability to make ATP it's what's left of a bacterial cell that's still doing it the benefit to the bacterial cell is of course here it is you know uh you know hundreds of millions billions of years later and you're still you're still in existence you're just living inside of a ukareotic cell now and you know you're no longer an active living individual cell but you're part of a bigger cell that's still alive and then of course the benefit to the ukarotic cell is uh it has a structure to create ATP for one final point to drive home that ukareotic cells do not make their own mitochondria that they are not capable of uh creating a structure like this on their own is that um your mitochondria came from your mother okay your mother's mitochondria are in the egg that's produced when the sperm fertilizes the egg it just delivers the DNA in your DNA you do not have instructions for making mitochondria you can't make these mitochondria make themselves so mitochondria with their own DNA and ribosomes are capable of replicating themselves so your mitochondria are genetically genetically identical to your mother's and not related to your father's okay so putting this all together this is what's called the endo symbiotic theory endo inside of symbiotic that relationship a symbiotic relationship is one where um both individuals benefit with the relationship so a a symbiotic relationship inside of ukareotic cells endo symbiotic theory states that mitochondria and chloroplasts are evolutionary descendants of bacterial cells okay so I hope you're amazed by that i hope you appreciate that that as we are learning about the bacterial world one of the things that we want to remember is we're part bacteria okay uh you would not consider the mitochondria to be bacteria anymore it's long evolved away from that but the mitochondria was created by endo by endocitizing or fagocitizing a bacterial cell okay the next few features I hope are just reviewed we have the endopplasmic reticulum which is a network of uh membranes inside the cell the rough endopplasmic reticulum works together with the Golg apparatus for the cell to make uh proteins that are then packaged and shipped to the outside of the cell and then the smooth endopplasmic reticulum is the site of lipid synthesis and metabolism and degradation and um also the smooth endopplasic reticulum um could serve as a site of calcium ion storage in examples like muscular tissue um so uh you know I won't take a lot of time here uh describing these hopefully you remember the uh actions of the endopplasmic particula um structure so we had the smooth and the rough endoplastic reticulum and gold g apparatus um so make sure that if you don't remember it that you go back through and you know refresh your memory on these but uh right now we're just keeping it to the general functions of each of these structures um we have two structures within the ukarotic cells that I like to describe as being the stomach of the cell the lossome is a membranebound structure that's filled with uh digestive enzymes and peroxomes are a membrane bound structure that are filled with oxidizing substances and in both cases the loss and peroxomes are structures that break down material that the cell um brings in through endoccytosis and fagocytosis so as material comes into the cell we have these structures waiting to connect to um to connect to what's been consumed and um introduce the digestive compounds to um break that material down so the cell can use it and with that uh you know I hope uh I hope everything uh you know came together well for your understanding of this topic um and as always throughout this course uh if that was you know if there's anything that was confusing about that I know a lot of this I I said I hope you recall this if you need any extra explanation on it uh please reach out to me and make sure that uh all this is making sense as we're going to be building on a lot of these concepts as we go through this semester