as I've said before we spend most of our time in micro talking about the procaryotic cell we probably have more experience in dealing with eukariotic cells so if you've taken a general biology class or anatomy and physiology class we tend to spend more time talking about eukaryotic cells which are a little more complicated so just to refresh our memory a little bit of the similar arities and differences of procaryotic and eukaryotic cells procaryotic cells are very simple cells so they are the oldest cell type so this is actually the precursor for eukaryotic cells there's no nucleus in fact it basically means pre- nucleus no fancy organel like the mitochondria they do of course have DNA and of course they're going to have to undergo all of the things that living things do they have to undergo metabolism they have to undergo generative properties they have to maintain homeostasis eukaryotic cells are much larger and they're more complex they do have several things in common as I said before they both share characteristics of living things they have DNA ribosomes if you remember learning about ribosomes that's where proteins are made so bacteria they need proteins just like we need proteins they both have cytoplasm and of course they both have a plasma membrane they're very very simple cells so in this chapter um we're going to spend more time talking about the basics of procaryotic cells I'll also give you some examples we'll also talk about some shapes and Arrangements of the bacteria what we're going to expect to see in lab so bacteria come in a variety of shapes as I mentioned before these are very small so to visualize them underneath the microscope we need that oil immersion lens we're going to need the highest magnification that we can get on our compound like microscope so because of their cell wall which is a little different procaryotic cells have a cell wall that will spend some time I'm talking about UK carotic cells unless we're talking about plants or fungi they do not have a cell wall cell walls are completely different so bacterial cell walls are different one of the things that the cell wall does is that it helps to give them their shape so these are the different shapes of bacteria and the different shapes that we will be seeing in lab so a very common shape that we see is a circle um and that shape would be a coxis if we're saying plural it would be coxy so you'll notice that I really like a lot of letter associations so I think about Circle begins with c coxide begins with c and you can see that that blue cell that looks like a sphere looks like a circle that is a coxis if we had multiples we would call it a coxy the other common shape that we see on the other side of the screen is the basilis or basil for plural and that is a rod shaped bacteria to me it kind of looks like a Good and Plenty candy um or almost like a capsule like if you're taking a Tylenol or maybe even a Mike and Ike candy so it's a little more elongated some look a little more like sticks um but it is certainly longer than the circle that we see with the cock's eye some that we'll see sort of an amalgamation of both of those and this is a coob bacillus coob bacillus to me kind of look like a little Tic Tac uh where it's a little oval but it still has sort of that rounded shape those are going to be the most common shapes that we will see this semester in lab there are some other shapes um and I'll talk a little bit about some examples of bacteria that would fall under these shapes one is vibrio and Vio is a comma shape or almost like an apostrophe shape spirillum has a little wave to it um sometimes in our prepared slides we're able to actually see that shape and spyroy is a little more like a cork screw shape as I said before the two shapes that we are going to be seeing the most is the coxy and the basili now I know that I use very different terms to describe just so that we kind of have a reference I'll call it a circle or a sphere what I want you to do is to get used to using those micro terms so instead of saying Circle instead of saying Rod make sure that that you're saying coxis and basilis we have lots of different terms to kind of describe what we're saying but in micro we want to make sure that we're using the correct terminology so this is an example of a Spyro and you might actually be familiar with this particular Spyro um an example is leptospirosis um and this is caused by a Spyro and humans can get this as well as animals and so if humans or even other animals are in contact with contaminated urine from maybe wild animals like birds or rats or mice they can actually contract um leptospirosis now there is no human vaccine for it however if you have pets um your dogs might have actually gotten a vaccine for this so sometimes we can actually see this disease arise in places where there's a lot of staining water so if there's a lot of flooding um if let's say that there was a disaster like an earthquake or a hurricane and now we've got standing water this is going to be a quick way for a type of bacteria like this to be transmitted so this is also the reason why if I'm drinking a can of soda or seltzer I'm always wiping off the top of the can one of the things that you will hear me talk about is that my mother was a nurse and that was one of those cases of a little bit of knowledge was probably too much because she was I I don't want to say paranoid but certainly aware of a lot of things and so one of the things that she taught me to do is to wipe off soda cans or even canned goods before you actually open them because that could be a way that leptospirosis is transmitted so if you think about these cans in warehouses um they're not the cleanest places they're going to be mice and rats running around and they could actually be be transmitted so my mother at an early age taught me to to wipe the cans of my soda and canned goods a few years ago I remember hearing in the news um and this was right after the earthquake in Puerto Rico and of course there was a lot of flooding there was a lot of Devastation uh there are a lot of dogs in Puerto Rico um that are running around that don't have homes that are Strays in fact my one dog um was a rescue from Puerto Rico and at the time after the earthquake of course they were sending help they were trying to get supplies in and one of the things that they were doing was that they were rescuing puppies so they brought the puppies back to New Hampshire and um they actually had the puppies at a local pizza place and I honestly can't remember the the town in New Hampshire but I do remember hearing this on the news and the reason I heard about it on the news was that people that had gone to the pizza place and visited with the puppies because they were trying to get them adopted uh they were putting an all call out on the news to say that if you had been in contact with these puppies you may want to get in contact with your doctor because the puppies had leptospirosis because of course they were coming from a place where there was staining water and Devastation so people were warned that if they were at that pizza place if they had come in contact with the dogs um to make sure that that they were going to see their doctor um again dogs can get the vaccine in fact I believe that both of my dogs um have actually had the vaccine for that an example of vibrio is Chala and we've probably all heard of chalera again in some areas where there is a lot of Devastation in standing water um this is how Cal can be transmitted and of course symptoms lots of horrific GI issues of course if you have GI issues then you risk dehydration which is not going to be a good thing um so sometimes we often hear about chalera as kind of a secondary um after devastations like earthquakes and hurricanes uh we will not be seeing any vibrio chera in lab we will also not be seeing any Spyro ketes in lab um but these are just a couple of examples since we are talking about some bacterial diseases um this is not a human health and disease class so even though we talk about these diseases it really is a standpoint from recognition not a lot about the pathology and all of the symptoms and treatments we won't be getting into that it's it's mainly for recognition so if you're like yeah I've heard of vibrio um you're going to know that yes that is a bacteria we will also be talking about some viral diseases so that you know the difference between okay yes I can recognize that as being a viral disease I can recognize that as being a bacterial disease so it really comes from a recognition standpoint so another thing that I have mentioned before is Arrangement and Arrangement happens when the bacteria are dividing so that cell wall helps to um give some protection to the bacteria it also is the thing that basically helps it form the shape when bacteria are dividing and we'll be getting into how they divide in the next chapter if they get stuck together this is when we can see different arrangements so it's not a complete separation they kind of get stuck together so some common Arrangements that we will be seeing um you will see mono so some just kind of like to hang out by themselves they separate very well during cell division and so they're not going to be stuck 2 by two or 4x4 so some you will see that are going to be by themselves and I usually call that mono Diplo is when we have two bacteria stuck together and we could see Diplo with coxy we could see two circles stuck together together we could also see Diplo with basili where we see two rods stuck together if we saw four that would be tetrad and we tend to see that with coxide not with basil just because the basili actually divide end to end so if we were to actually draw out a basill and I'm going to attempt to draw a basill right here if it were to divide it's actually going to divide end to end so we would see Diplo we could actually see a chain of them together and that would be strepto of course we could also see strepto with coxy as well but we tend to see fewer arrangements with the basili just because they're going to be dividing end to end and that's how they would get stuck whereas if you think about a circle they could actually be dividing around that all of the planes of that Circle so like I said we tend to see more arrangements with coxide than we do with basili so common Arrangements that we will see Diplo strepto tetrad another common Arrangement that we will see is staff and staff is when they're arranged in sort of a grape cluster and we would only see staff with coxy and I'll Circle the picture where you can actually see staff so if you look at these individual cells they're these little tiny circles and they're stuck together and almost like this grap like Arrangement and so to me they kind of look like Bunches of grapes or Bunches of balloons if you look at this picture it almost looks like lace so where they're kind of gathered together and then you kind of see the spaces in the middle we would only ever see um staff with coxy so the most common Arrangements that we'll see mono Diplo strepto and staff we will see one organism that um likes to hang out in Arrangements of four tetrad if they like to get stuck together in groups of eight that would be saren and saren is kind of like a strange sounding word um to be honest I don't believe that I've ever seen sarsen SAR can also would be kind of difficult to see because if it is in tetrad um you might kind of mistake that because you might see four up front but there's actually another four behind it it's possible to also see like rosette or a star shape I'm going to be honest with you I've never seen star shape underneath a microscope I've only ever seen it in pictures so we are going to spend um quite quite a bit of time looking at cells identifying their shape and Arrangement so here's my little drawing right here and this kind of shows you the different Arrangements that you can see um if you notice that bottom picture I have a big X through it we would never see unless we had a really thick sample it might kind of mistake it for this arrangement we would never see kind of piled high like a stack of pancakes just because that's not how they divide so the only way that the basili are going to get stuck together is end to end so we would see mono we would see Diplo we would see strepto as I said before because of the coxide because of the circles and dividing on those different planes that's when we tend to see more arrangements so this is just a little reminder that we are not going to be seeing basili in staff we won't be seeing them stacked up like pancakes so we'll be talking a little bit more in detail about the bacterial cell wall as I mentioned it is completely different makeup than something like a fungi or a plant that has a cell wall it's completely different it helps to give it its shape it also helps to protect it to a certain extent um and one of the things that will be be doing in lab is doing some stains so that we can differentiate and again one of those differential stains where we can differentiate between bacteria based on their cell wall so we're going to be looking at a little comparison of our bacteria and the different types of cell walls but first we'll talk about some of the components that we might see in a cell wall so first up is pepti glycin another name for pepti glycin is murine this is really the most important part of the bacterial cell wall eukariotic cells are not going to have peptido glycin this is going to be something that we're only going to see with bacteria these procaryotic cells this is like the fence-like structure so this is going to be outside of the cell membrane and it's going to help to keep things out and of course keep things in we're going to be seeing pepo glycin although it's in different thickness in both gram positive and gram negative organisms and before in chapter 4 when I was talking about the Graham stain that Graham stain because it's a series of stains is going to allow us to see if that organism is gram positive or gram negative that's going to tell us about its cell wall now as far as a clinical standpoint why would this be important this would be important because if you have a patient that has a gram positive infection you want to make sure that you're finding an antibiotic that is going to be targeting those particular gr positive bacteria so this is why it's important from a clinical standpoint to do our Gram stain so we are going to see this peptidoglycan in gram positive gram negative and even acid fast bacteria that I'll talk a little bit about another thing that we would see in gram positive organisms is teic acid and we only see this with grand positive organisms and they believe that perhaps it has some ion transport function and this also kind of serves as a docking station for certain viruses and there are certain viruses that only attack bacteria and we call those bacterio phases and so this serves as a docking station for it if that virus can't attach to a cell then it's not going to be able to replicate so that's why that attachment point is going to be really important um in regards to the virus um and its ability to replicate we can also see an outer membrane so we would only see an outer membrane in gram negative um and when I show you the picture of the gram negative organisms I kind of describe this as kind of like a peptidoglycan sandwich where we'll see an inner membrane a a layer of peptidoglycan and then an outer membrane on the top we would only see that in gram negative something else that we talk about with the outer membrane is LPS or lipopolysaccharide this is actually an endotoxin so it can be really toxic if it's found in large quantities and this is actually something that can cause endotoxic shock which sometimes happens with the elderly so if we have a massive kid of gr negative bacteria as that cell lices it's going to be releasing a lot of that endotoxin and this can actually cause endotoxic shock where the person has a high fever it causes blood vessel dilation and their blood pressure can start to plummet we can also see in gr negative bacteria this perlas space so this is kind of like that gap between the cell wall and the cell membrane remember bacteria they don't have a mitochondria if you remember mitochondria is where um ATP is made so they can actually use this space to undergo some cell metabolism with some of those electron Transporters I'm a visual person honestly so I think it's a little easier to see the makeup of the cell wall by looking at pictures so this is just a little summary page of of what I talked about before so gr positive bacteria and one of the things that you will notice is that um I like a lot of letter associations so if we think about gram positive positive begins with P they will also retain the crystal Violet in the Graham stain that is the primary stain so they will appear purple and they also have a thicker layer of peptidoglycan so we're looking at three words that begin with P positive pepti olyan and purple so that's how I like to remember our gram positive organisms gram negative organisms they will actually retain the counter stain and they will look red underneath the microscope because that counter stain is safranin or saffrin however it is that you'd like to say it so as I was saying before um the gram negative organisms I think it's kind of like a pepo glycin sandwich so here's the inner membrane and then here is the peptidoglycan and then here is that outer membrane so what happens in the staining procedure is that we add the primary stain then the Morant which is the iodine so that we can get this complex to stick to Grand positive cells but but then we also go through a really critical step which is called the decolorizing step in that decolorizing step we use alcohol and what it does is that it basically wipes away this outer membrane and strips out that Crystal Violet so then when we apply the counter stain then that safranin will actually stick to that pepto glycin and it's very convenient that this pen is red right here and that's why that organism looks red in color um it really looks more pink but I don't want to confuse you with the P's that we already talked about um with our grand positive organisms so that's the difference between gram positive and gram negative acid fast bacteria they do have a thin layer of pepo glycin but they have this really thick lipid layer this molic acid and they are really hard to stain because of it so we actually have to use a special stain carbal Fusion which is a lipid die that will actually adhere to that molic acid then we do an acid wash and this acid fast bacteria will resist that acid wash and hold on to that pink dye so they will actually look pink underneath the microscope like a really bright pink now because of this heavy lipid layer which is almost like a suit of armor they are really resistant because of this so really hard to kill there's not a lot of um disinfectants and antibiotics that will work on them and because it's tough to get those waste products out and nutrients in they are very slow Growers and we're going to be talking about the growth curve and generation time acid fast bacteria are much slower Growers than our typical bacteria that we will see so as I mentioned and I promise that we would be looking at a picture and here is our picture of our gram positive and gram negative bacteria so if you take a look at that top picture that big purple layer that's aepo glycin that popsicle stick looking structure that's that toic acid that has a role in ion transport also where the bacteria phase can adhere and then if you look underneath that big purple layer there's that inner membrane and so they have a phospholipid by layer just like we have a phospholipid bil layer if you look at the second picture here's that Pepto glycin sandwich that I was talking about we've got that inner membrane a thin layer of peptidoglycan and then that outer membrane you'll notice that there's that lipopolysaccharide that endotoxin which is part of that outer membrane so you can see where it kind of looks like that Pepto liken sandwich by contrast if we look at our acid fast bacteria there's a thin layer of pepti oen but there's that really thick lipid layer that's going to act like a suit of armor to help protect them on the flip side of that it makes it really difficult to kill them because of that suit of armor they're also very slow Growers so an example of an acid fast bacteria that I know that you've heard of is tuberculosis and tuberculosis affects millions of people worldwide um sometimes people can actually have tuberculosis and not know because it's such a slow grower that their immune system just kind of keeps it as Bay there are also different um different strains um the genus of um bacteria that do cause tuberculosis are mobac ium we will actually be doing an acid festing with a myobacterium don't worry it is not myobacterium tuberculosis it's microbacterium Smeg modus um which is not varent like tuberculosis is and what happens is it most of the time affects the lungs um and it they can actually multiply inside a v macroasia so if you remember the lvi those are the functional units of the lungs um and our body body can't really handle it so we end up building like these granulomas these walls of cells to basically kind of keep it isolated most often we think about tuberculosis in the lungs it can actually spread to other organ systems this is ter milary tuberculosis one of the things that you will hear me talk quite a bit about is that my husband has Crohn's disease and it took a couple of years to actually diagnose him and they ended up doing an explo oratory surgery trying to figure out what was going on and when the surgeon came out he said If This Were another country I would think that this was tuberculosis and that was because of the inflammation that was actually in a small intestine so it can actually affect other parts of the body problem with tuberculosis because it is such a slow grower and it's got that suit of armor that lipid layer it's really tough to kill so there are not a lot of antibiotics that work on it people that are on antibiotics for tuberculosis are usually on for a long period of time and of course we know that some strains are drug resistant and so that makes it particularly nasty to try to control so that is an example of an acid fast bacteria another example of an acid fast bacteria is leprosy and this is caused by myobacterium lepre now I remember when I was a kid hearing stories about leprosy like people's limbs falling off and I was like what on Earth is that it's not quite as bad as that they're of course lesions I used to hear stories about people being shunned like they had to live in um islands and Far Away places because they couldn't be around people um again it's not that highly contagious of course people that do have it uh they have to be very careful about Linens and utensils um but again because we live in the day of antibiotics um it is not quite the horror story that it was and we certainly know more about bacteria again just uh just so you're aware we are not going to be looking at this particular acid fast bacteria either and again just as a reminder as we are talking about the different types of bacteria this is more for recognition um than than anything else all right so a little bit more detail on our bacterial structures so first off our internal structures so those spet those um Quirk screw shape bacteria in order for them to move they actually have axial filaments that kind of allow them to twist so that's how they move of course bacteria are going to have cytoplasm just like our eukariotic cell would have cytoplasm they also need structures to make proteins and those are going to be the ribosomes coming up in a chapter we're going to be spending a lot of time talking about protein synthesis and if you've learned protein synthesis and how it works in eukaryotic cells it's very similar in procaryotic cells of course because they are bacteria the enzymes are going to be a little different the ribosomes are also a little different structure so just like eukaryotic ribosomes there's a small and large subunit small subunit is 30s and the large subunit is 50s and we would term those 70s ribosomes now I know you're looking at 30 + 50 and you're going that does not add up to 70 yes it doesn't have to do with the math that s actually means the sediment coefficient so if you were to spin them down in solution with a centrifuge that's actually how they would settle out so this is just to show you that the ribosomes are a little different and we're going to talk a little bit more about that detail later on because there's not a nucleus they don't have a area that is going to enclose their DNA of course they are going to have DNA but if we had a very strong microscope we might see a nuclear region where it was a little darkened that's going to be their circular chromosome so their chromosome they've only got one is a circular chromosome sometimes they could actually have a plasmid so if I draw out a picture of a bacteria right here very simple cells so here would be their circular chromosome and some of them might have a another piece circular piece of chromosome which would be a plasmid and a plasmid is extra DNA so this is not necessary for the survival of the bacteria this has nice to have genes so all of the necessary genes are to be on the circular chromosome but some bacteria can have plasmids that can offer some useful genes like maybe some antibiotic resistant genes so not all of them have plasmids some of them do and um it can offer some useful genes for them for example antibiotic resistant genes some would have chromatophores so we would find these in photosynthetic or cyanobacteria so that means that they would have pigments that absorb light energy so that they could actually make their own food because this is more of a clinical based class than an environmental we're not going to be seeing any bacteria with chromatophores again if we had a really powerful microscope we might see some small inclusions like little granules or vesicles and another structure that we might see is an endospore and I mentioned endospores before these are not means of reproduction these are means of protection and I mentioned that coming up soon we will be doing the Spore stain and this allows us to see whether or not the bacteria makes a Spore so a bacteria would make a Spore when times are tough so if they think that conditions are rapidly declining there's not a lot of water not a lot of nutrients maybe they've been exposed to a lot of UV radiation or chemicals they're going to go into this Sur survival mode so basically they're going to go into this protective mode where they develop this protein coat and then they've just got that DNA protected by that protein coat so they're just dormant waiting for better times and a lot of these endospores can actually stay in soil for years and years like they've even found thousands of years the metabolically active cell so the cell just going about its business doing its job this is what we call a vegetative cell they haven't quite gotten the memo yet that they need to go into this protective form so as I mentioned with the Spore stain that differential stain is going to allow us to see the differences between those vegetative cells the metabolically active cells and the endospores the cells that got the memo conditions are really deteriorating and now they need to go into this protective mode where they've developed this protein coat around their DNA a Genus that we see as a Spore forer is claustrum and so we'll give you a couple of examples of claustrum um if you've ever worked with patients with C diff that is a spor forer and that is what makes it very very tricky to treat and get rid of so we'll be talking a little bit more about those endospores some other ctle structures so some bacteria might have pilli or pil whoever it is that you'd like to say it these are Hollow projections as we get into our molecular biology chapter we will talk about how bacteria can actually transfer genetic information so one bacteria sitting next to another bacteria can actually transfer some genes like some useful genes like antibiotic resistant genes in order to do that they would need a conjugation pilli and so we'll be talking a little bit more about that process some of these pilli can actually be attachment pilli so almost like these little stickers that allow them to stick to surfaces if a bacteria can stick to a cell that means it's going to be more dangerous to that cell and that means it can be pathogenic some bacteria will have a glycocalix a thick layer of polysaccharide on the outside of the cell um a really thick polysaccharide layer that glyx would be a capsule and again that capsule is going to help to protect the bacteria and again if it's protected it's going to be more dangerous some will have a thin layer of glycocalix almost like a slime layer that will allow them to adhere to things it also helps them to resist drying we would actually see this with um Dental carries and dental plaque so this is what is keeping our dental hygienists in business bacteria can also move just like UK carotic cells do they can have fella just like you carotic cells can and a flagella is a tail probably about half of bacteria are modal they can move and they have these flagella their Arrangement is a little different than UK carotic flugel in fact you can see with the picture um how simple they are compared to a complex fella in a UK carotic cell the way that they move is also a little different as well and we can have a variety of configuration so manatus would be one Vella andricus would be two Vella one at each end latus two or more fella at one or both ends petrius means that they would be all over the surface so peri means around so they would actually have all of these flagella around the perimeter and they can actually move this fella in different directions to help them move towards things that are good like nutrients or even away from bad things like maybe chemicals or hazardous things so this is another picture of the different configurations of fella so you can see that petrius where it's got those fella all around so here is sort of a generic version of a bacteria where we can see the inside you can see that chromosome this one happens to have a plasmid we can see ribosomes again we're not going to see mitochondria endoplasmic reticulum they are not that complex on the outside you can see where this one has a glycoala we can also see the cell wall and the cell membrane and also this one has a flagellum as well so relatively simple compared to our eukaryotic cell that we will talk about so I mentioned that bacteria can actually move their flagella in different configurations to allow them to move towards things that are good like if there was a plate of chocolate chip cookies on the other side of the room I would run towards it or to steer away from things that are bad if maybe there's hazardous waste or chemicals um in their vicinity so this movement of either going towards something or away from something is what we call chemotaxis now if you were to Google chemotaxis and look up videos on YouTube it's really complex so these bacteria would have receptors those chemicals are going to bind to The receptors and then it kind of kicks off this whole cell signaling to actually move the flagella in different directions so if the fella moves the um if the bacteria moves their fella counterclockwise that would equal a run where it kind of goes towards something if they were to move them in a clockwise direction that would result in a tumble so of course you know that I like letter Association so I think of counterclockwise counter has an R run begins with R now this is not as sophisticated as like running towards something like a plate of cookies this is what they call more of a random bias walk where they're kind of like sighing back and forth almost like to me like a toddler you've ever seen a toddler learn how to walk they're kind of like you know moving all over the place kind of like winding around they can't quite make that beine yet so this is not like okay they're going to move right towards that nutrient or right away from something that's hazardous they kind of like go towards something and then kind of tumble away um I did post a video on this just so that you can kind of see um the movement of the FL um and how they can they can do this random biased walk but it allows them to go towards something or away from something and we turn this chemotaxis so by comparison our eukariotic cell is much more complex and this is probably what we're more familiar with so here is a generic eukaryotic cell where it's going to be bigger and if you look inside we've got all of these fancy cell organel this one has a chloroplast so this must be a plant cell we've got the nucleus where we're going to contain the DNA mitochondria we're going to make ATP this is much more complex so how is it that these complex cells came to be well procaryotic cells were the first on the scene so they arrived way before eukaryotic cells did and UK carotic cells did not evolve until about a billion years ago so this theory of endo symbiosis is how eukariotic cells evolved from procaryotic cells so if we kind of dissect the word Endo symbiosis Endo means in symbiosis is when organisms are living side by side and the theory of endosymbiosis is that there were larger procaryotic cells that gobbled up smaller procaryotic cells and they lived side by side eventually those procaryotic cells living inside that larger procaryotic cell evolved into organel and we can actually see this with our mitochondria and our chloroplast so if you look at this first set of pictures we've got this larger procaryotic cell and the smaller obic bacteria moved into this larger procaryotic cell now they were both happy because the smaller arobic bacteria got a home it got shelter and it was able to make energy for the larger procaryotic cell so they were both very happy living side by side over time that aerobic bacteria ended up evolving into the mitochondria so it's not like you could actually take out that mitochondri and then it could live by itself it had evolved to be this specialized organel if we look at the evolution of the chloroplast here we've got that larger procaryotic cell gobbling up that cyanobacteria and again both of them were very happy larger cell got some food that that cyano bacteria was making for it and that little cyano bacteria got a home and protection over time that cyano bacteria evolved into the chloroplast so I know what you're thinking it's the exact same thing that I was thinking about when I heard this I was like well that's a nice story um but is there evidence of this well there actually is evidence and this is not comprehensive list but this is some evidence for endosymbiosis so first off mitochondria and chloroplast are the same size as procaryotes so same size as are bacteria okay that's not really conclusive enough but wait there's more so mitochondria and chloroplast also have their own circular DNA H who else has their own circular DNA we just talked about the DNA and procaryotic cells they too have circular DNA I also mentioned those ribosomes and I mentioned that math that doesn't quite add up with that large and small subunit but bacteria have 70s ribosomes compared to the 80s ribosome of eukaryotic cells mitochondria and chloroplast also have 7ds ribosomes and if they have similar ribosomes the way that they carry out protein synthesis is going to be very similar coming up soon we'll talk about how bacteria divide the way they divide is very simple it's called binary fision where they double their DNA and then split into two mitochondria and chloroplast of divide the same way I also talked about that gram negative cell membrane and cell wall and the mitochondria and chloroplast have that similar double membrane to that gr negative bacteria and again there are some other structural similarities like the chloroplast is also similar to our cyanobacteria so there is evidence to suggest that our modern J eukariotic cells evolved from these procaryotic cells so these smaller procaryotic cells moved inside the larger procaryotic cells they were both very happy and eventually it evolved into the chloroplast and mitochondria the last thing that I just want to mention is that procaryotic cells these cells are going to be prone to the environment and kind of at the mercy of their environment just like our cells are and so so they need transport they also have to maintain a high surface area to volume ratio just like our UK carotic cells do so when we talk about cell transport such as diffusion osmosis active transport we're going to see the same types of things with procaryotic cells the one thing that procaryotic cells excel at is maintaining this high surface Sur area to volume ratio this is really important so that cells can maintain the exchange with the environment so that they can get nutrients in and they can get waste products out so if we have a small procaryotic cell right here and it needs to get waste products out there really isn't a far distance for that waste to travel and so their surface area so the surrounding area compared to the vol volume is going to remain high that high surface area to volume ratio so by comparison if we were to actually look at a larger cell like a UK carotic cell here much bigger cell if it's trying to get waste out of the center it's got a longer way to go so that means that those waste products can start to build up that's not a good thing so procaryotic cells they have the market cornered as far as maintaining that high surface area to volume ratio because they're small in fact the first rule of maintaining a high surface area to volume ratio is to stay small like a procaryotic cell our eukaryotic cells are not that small so how do we do it well there are some other mechanisms to maintain that high surface area to volume ratio so some cells can kind of elongate and flatten out so again if it's trying to get waste products out now it's got a shorter distance to travel the other thing is folding things so this is one thing we talk a lot about in biology anytime you fold something you know that you are increasing that surface area and then compartmentalization so if we've got like our mitochondria here and we've got our nucleus we're extending that surface area so now we're adding that more surface area by compartmentalizing all of those functions and that's going to increase that high surface area of volume ratio procaryotic cells they have that market corner because they can stay small but again they are going to be at the mercy of the environment just like our cells will be as well so that is a little bit on procaryotic cells we are going to be continuing this of course looking at our procaryotic friends in lab as well and again I will give you more examples of bacteria but again it's more from a recognition standpoint than anything else