General Biology

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27. Protists

Protist Lineages

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Excavata and Archaeplastida (Plantae)

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Hi. In this video, we're going to talk about some of the key lineages of protests. Up first are the excavator, which are a major group of uni cellular. You carry outs. Many of the species in this group actually lack mitochondria That we'll talk a little bit more about that in a second. And most of them also reproduce a sexually. Now, first up are the diploma nods. Uh, interesting thing about diploma in ads. They lack mitochondria. They actually contain this reduced mitochondrial structure that lacks electron transport. So, uh I mean, first of all, that means that these guys are having anaerobic metabolism, but additionally, it means that they did undergo Sim biogenesis. Right? That did occur. Uh, but now they're mitochondria. Have taken on this other form, you know, evolved to be different than what we know of as mitochondria. Interesting thing about diploma in ads. They have two nuclei you can see in this picture of a diploma in ad. Right here we have two nuclei. This is actually giardia intestine. Alice. Nasty little parasite will make you very sick. Last thing you can see that cell has Thies flag. Ela uses those for motion All right. Next up, the pair base lids can see These guys are right here, and they also lack mitochondria. Use Fla Gela to move. Cool thing about, uh, some of these species is that they will undulate there. Membrane almost, you know, think of. Ah, like a manta ray or something. Swimming. That's sort of what it's like. They'll undulate there membrane to move. Many of these species are parasitic a zwelling. Next up, we have the glina zones, which are the some of the earliest cells known to contain mitochondria. And among them we have Canada plastics, which you can see right here. No lasted. And this is actually trypanosomiasis, which is a a protest that causes a sleeping sickness. And it's transmitted by the African set fly. It's a no, you know, big problem in sub Saharan Africa. This this disease, the sickness. Uh, little interesting thing to note about these cells is that they lack mitochondria. I'm sorry. They have large mitochondria. Not that they lack mitochondria. Next up, we have you glean. It's right here, and these guys contain chloroplasts. Look at that. See these Nice chloroplasts in there. Some of these species are photosynthetic um, many. Our hetero trophic and photosynthetic. So they're mix the troughs mix a trophy just means that they're photosynthetic and hetero trophic. Another major lineage are the our keep last, Etta. Sometimes these air just referred Thio plant I, uh, technically are keep lasted A is like, uh, slightly broader categorization. Um, plant I technically doesn't include red algae, for example. Or if we were in England, I'd say algae, but I'm not gonna do that to you now. Uh, the this group is a another major modify let ICC group of eukaryotes. And it is the group that contains green algae and land plants, which we're gonna talk about in a later trapped er more extensively. Now, these organisms originate from, uh, protests that engulfed cyanobacteria by end of symbiosis. Right. So we're talking about a primary and a symbiosis, not secondary. In fact, a lot of secondary symbiosis happens with red algae and speaking red algae. These are mostly multi cellular organisms. Some contain multiple nuclei, and many reproduce via alteration of generations. Pretty cool thing. They contain this photo synthetic pigment called fico. A wreath rin a wreath rin like a wreath. Recite red blood cell right, So red kind of pigment again. This is a photosynthetic pigments actually masks the green from chlorophyll. That's why these appear red and something pretty cool. The red intensity of these cells actually correlates with depth. Just interesting little fact. Now, green algae are much more similar to land plants, and they have a a similar composition of photosynthetic pigments, tow land plants as well. And they can actually be broken down into two groups. Care fights, which are algae that are most similar. Tow land plants. You can see an example of those there and chlor if ICTs, which are a mix of eunice cellular and multicellular species that have a half Lloyd dominant life cycle, All right with that, let's flip the page.
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Stramenopila and Alveolata

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the s a r Played is a modify. Let ICC Super Group made up of the clay Edstrom Anna Pilla Alvey, a lotta and raise area. Many of the organisms contained in this supergroup are photosynthetic, and this is also the group that contains the water molds, which you hopefully realize are not actually molds, because these are not fun guy thes are protests. So again, just another case where there's a bit of a misnomer in the biological terminology, which hopefully you're starting to see. It happens all the time. It's just partisan. It's unfortunately anyhow, stream in a pillow and al violates contained chloroplasts. And those chloroplasts likely arose from secondary end of symbiosis. Which, you might remember, was when Eukaryotic Cell engulfed another eukaryotic cell that had already undergone into symbiosis and already had chloroplast inside of it. Most likely, this was a red algae that was being engulfed, so the stra MENA pilla are mostly made up of photosynthetic algae, and they are both uni cellular and multi cellular organisms. And the, uh, feature that defines this group are these flu Gela that have hair like projections. And you can see in this image of a generic stream in a pillow cell right here that we have this flag Ela coming off the cell and it's got all these little lines coming off of it. Those they're supposed to be the hair like projections. Now. Many species in this group exhibit deployed dominant life cycles and die atom's are no exception. Thes are uni cellular photosynthetic organisms whose key features that they're encased in these protective shells. They're actually made of silicone dioxide so kind of different from a sea shell, for example. But, um, different chemically but kind of the same idea. It's a protective casing for the organism. Now, as you can see in this image here, die Atom's come in a wide variety of morphology. Ease these air all little different shapes and sizes of the DIA, Tom's shells and fun fact. These have actually been arranged by people on slides as an art form. Yeah, believe it or not, people will take brushes that have a single bristle and working in a microscope. Well, actually, poke around little diatoms and arrange them into a collage like you see here pretty, pretty funky stuff, and this is not actually a modern thing. People have been doing this kind of art for, really, surprisingly, a long time. A super cool thing about die Atom's even though they're these tiny little microorganisms, they're actually responsible for, ah, lot of Earth's photosynthesis, and they can actually have a noticeable impact on atmospheric carbon. So when they spring up and, um, you know, there's, ah, large amount of them concentrated in a certain area, you can actually, um, notice a significant dip in the amount of carbon in the air in that area because they're using up so much of it for photosynthesis. Super cool. Now, gold algae like we see here, have a distinctive kind of yellowish brown color. They get that from these yellow and brown carotenoids, which you might remember. Carotenoids are a type of photosynthetic pigment in plants. They're usually like, um, accessory pigment. Um, here they're the distinctive pigment that is coloring the organism that we see. Uh, most gold algae are uni cellular organisms, and even though they contain thes chloroplasts, which just quick reminder came from secondary and a symbiosis, right? So probably a red algae being engulfed. Um, even though they contain these chloroplasts, many of these organisms are actually mix the tropes, meaning that they do photosynthesis. But then they also obtained nutrients like hetero trophy as well, so they mix it up right. That's where the term comes from now, lastly, we have brown algae, which you can see in this image here in a multi cellular form, is a big help stock. But brown algae can also be uni cellular. And, uh, it gets its distinctive color from brown carotenoids similar to gold algae and cool thing about these big help stocks, right? Thes air are large, large structures, and they'll actually be routed often the sea floor. But they want to get close to the surface because that's where the sunlight penetrates best, right? They're going to get the most sunlight at who hired depths. If that makes sense higher up closer to the surface, they're going to get more sunlight there. So they actually have these little gas filled chambers in there photosynthetic regions that caused these kelp stocks to float up to the surface so that they can obtain sunlight more efficiently. And that's why when you see like big clumps of seaweed or kelp or whatever on the beach, and they have all those little bubbles that are pods or whatever that are kind of fun to pop open. Um, that's what those air actually for there to cause the organism to float to assist with photosynthesis now worth noting that brown algae reproduce via alteration of generations and they could be both hetero and ice anamorphic, we saw examples of that in the lesson on protests. Life cycles Now moving on. We have LV, a lotta, and these protests are sort of the defining feature of this. Claytor are these membrane enclosed sacs called alveoli lie that are right under the plasma membrane. And we're actually going to break up our discussion of different types of out Alvey a lotta over a few videos because I want to get into some specifics about some of these subgroups. So first off, let's talk about Dina fragile. It's, um, I have always sort of thought of Dinah fragile. It's as being kind of similar to, uh to die Atom's. And that's mostly because they both kind of have, like, a protective shell, and they're both kind of like a plankton. Basically, um, I'm not saying that they're exactly the same. There's many differences there in different clay aids, merely merely trying to say that there are some parallels between them now, Dina. Fragile. It's air, mostly uni cellular again, mostly aquatic. And they're actually not enclosed by silicon dioxide shell, but by these two cellulose plates. And you can see in this image of a diet, Tom, here we have. Ah, this plate and then this one, too. So this is the two plates coming together, and you can see that over in this image, This diet Tom looks pretty different. Totally normal. That is the way they're supposed to look. Or that's ah, way they can look, I should say they come in many shapes and sizes. Um, now our dining flag. Let's rather have to flow. Gela. Yes, this is sort of where their name is coming from, but these flu Gela are pretty different. One projects outward, and another actually runs around the groove between the two plates. So, um, on this Dina flatulent here, you can probably see this flag Ela coming off of it on it might be a little harder to make out, but there's actually flew Gela running around the side of this organism kind of doing a loop around it. Right? So those are the two Fla Gela of the organism. Now, roughly half of Dinah flag bullets are actually hetero trophic. And about half our photo trophic though many of these photo trophic dina fragile. It's air, actually. Mix the troves, right? So again, um, they perform photosynthesis, But they also are going thio obtain nutrients, huh? Hetero trophic fashion. Now most dina flag. Let's have chromosomes that lack his stones and actually attached directly to the nuclear envelope and a structure called Dino Carry on. And last thing about Dina fragile, it's you can see here an example of their life cycle, which is a hap Lloyd dominant life cycle. Right. So these cells, um, these are some of these cells I should say are hap Lloyd. Let me get new color here. Right. So we've got these nice hap Lloyd cells, right? These two, our hap Lloyd, And they're gonna fuse together and form this deployed cell, right? And and to end train show happily deployed, right? And then this is eventually going thio, uh, go through my Asus and form those half Lloyd cells again. Um, so with that, let's flip the page
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Apicomplexans

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AP complexes are a type of Alvey, a lotta that are all parasitic and mostly their parasitic thio animals. Their cells lacks illion flow, Gela, and contain these modified plast IDs which are called a pickup last IDs. Most likely these arose from red algae, which remember, are acquired so they would have been acquired. That is, by secondary end of symbiosis. Now, these cells names basically the name a PICO complex and comes from the fact these cells have what are called a pickle complex structures. So here we actually in this image, we actually have two cells, hopefully can see them. I'll try to outline them right here. And hopefully you can kind of notice that these cells have these tips. Those are the A pickle complex structures and essentially, essentially, these a pickle complex structures are there to help these cells penetrate into their host cell, which, uh, kind of reaffirms the fact that they're all parasites right there. Defining feature is something that enables their parasitism. Now, other cool thing about these organisms is they have kind of interesting life cycles. Um, they reproduce both sexually and a sexually and that actually sometimes move between species to do so. So uhh an AP co complex in that is near and dear to my heart, is this organism called tox? Oh, plasma mosa. It's actually group of organisms. It's a genius. So toxoplasmosis are these cool a PICO complex ins and they reproduce sexually in cats so they have sexual reproduction cats and then they actually will be excreted. So the cat poops him out. They live in the intestines of the cat. They reproduce sexually there, and then the cat poops him out and they'll get picked up by other animals and they'll reproduce a sexually in these other warm blooded animals. And important to note, people are actually, um, able to be infected by these organisms. And what's so cool about toxoplasmosis is they actually go into animals brains, and they change their brain wiring. Basically, um, specifically, they make rodents like we see here, they make rodents stop being afraid of the smell of cat of cats basically so that the organisms like these rodents that get infected with Toxoplasma. So stop being afraid of cats which are their predators, right? And then they'll be eaten by the cats again. And that is how the toxoplasmosis A. We'll get back into the cat, its intestines or they can reproduce sexually again. So kind of this really weird life cycle, right? All revolves around this very strange kind of crazy feature of these organisms where they can rewire a rodents brain to make them stop being afraid of cats. Totally wild. Also kind of side note. But this is sort of they do affect the brains of other animals, too. And this is sort of people have theorized there's no real scientific basis to this. But people have theorized that this is sort of where the idea of the cat lady comes from ranches, all these, you know, a person who has a lot of cats and is like, kind of weirdly obsessed with castle. It's because of the toxoplasmosis have gotten to their brain. They've been converted. You know, I'm just kidding. But just fun, Little weird idea that relates back to these class of organisms. Now, I also want to talk about the parasite that causes malaria Plasmodium and these organisms also a PICO complexions also have in interesting life cycle where they reproduce, um a sexually and form their Hamida sites in humans and then in mosquitoes They form zygotes and produce what are called spores sites, which, you know, you think back Thio alteration of generations. These air kind of like spores. So similar idea. They're a sexual felt there units of the organism that will reproduce a sexually and eventually form comida sites. So let's take a look at this life cycle. So you don't really need to worry too much about the terminology here. All the individual steps I just want you to have, like, a general sense of how this works. So the commedia sites, we'll get together inside the mosquito, they'll form. Um, what is essentially sort of like this? I go again? The tip terminology is different here. Oh, cyst is ultimately what they're forming, which is basically just full of those spores sites and those spores sites will, um, when a mosquito bites a human, the sport sites will be passed into the human's blood stream. They'll make their way to the liver where they'll infect liver cells. That's kind of what's going on here. They're gonna infect liver cells, and they're going thio ultimately form these structures again. Don't worry about terminology too much they're gonna form these structures and liver cells that will then infect blood cells. And those infected blood cells are where the Goa media sites will be produced. Right? And then, of course, mosquito drinks your blood, right? The mosquito will slurp up your blood. And those go media sites will get back into the mosquito where they conform the gametes and the Asus and eventually, more sport sites to infect mawr humans. So pretty crazy life cycle here, right? Not only are we switching between organisms, but within humans first, something has to happen in liver cells, and then something has to happen in blood cells. There's, like, complex stages to this life cycle and totally wild that this organism, right this plasmodium depends on moving between, um, mosquitoes. And it's not just humans, animals in general, but still moving between mosquitoes and, uh, and animals like humans or cows or whatever totally wild, wild life cycle. Um, that, you know, requires the movement between species. So it's kind of ah, weird and cool thing about some of these a PICO complex and species. All right, let's turn the page
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Ciliates

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silly. It's air, the last type of Alvey A lot of that I want to talk about and they get their name from the fact that they're covered in cilia. Hopefully, that makes sense. Uh, they use these cilia for movement and feeding, and mostly they're feeding by preying on bacteria's these air predatory organisms. A cool thing about cilia. They have this deployed micro nucleus that is on Lee used for reproduction. And they have this polyp loi de, um macro nucleus that is used for transcription purposes. So gene expression is happening from that macro nucleus of which there are many copies of the of the chromosomes. Whereas, uh, the micro nucleus is, uh, just has two copies of chromosomes and is on lee used for reproductive purposes. Now they can reproduce a sexually by binary vision and also do this unique form of sexual reproduction. So I kind of wanna talk about that right now and just f y I Here we have two silly. It's, um these are actually a sexually reproducing right there. Uh, about two separate right there. And hopefully you can see kind of might be a little too faint to see, but There's some cilia coming off these cells. No. How does the sexual reproduction work? Well, it involves the micro nucleus, as you might recall. So basically, um, there are, You know, the specifics of this are much more complicated than I want to get into. I really just want you to walk away with kind of like a general sense of how it all works. Don't really need to worry about terminology and specifics. Just you get an idea of, like, another type of life cycle experienced by you Carry it. So, um, there are, you know, well to say, let's put it this way to cells will get together, and they'll sort of form a pair. And you can see they've the two cells air being distinguished here and here by their different colored micro and macro nuclei. So what's gonna happen is these micro nuclei remember these are deployed. They're gonna undergo my ASUs, and we're gonna wind up with, um, these Hap Lloyd. Right? So now these micro nuclei are hap Lloyd thes have exes in them because they're not going to be used. Just these are going to partake in the reproduction. So, um, so some of these. You know, some of these micro nuclei that are generated from my oasis are unused. The cells will actually just exchange. Oh, you know, one micro nucleus or micro nuclear micro nuclei. And that's what we see happening here. The cells are exchanging micro nuclei, and then so we're still Hap Lloyd here, and then those micro nuclei are going to fuse together. So that's that's what we're seeing here. Now, these micro nuclei here and here these are deployed again. Then what's gonna happen after we have a fusion of the micro nuclei we're actually going Thio have a bunch of Might ASUs occur on both the micro nuclei and the macro nuclei theme The unused or sorry, the original macro nucleus is going to disintegrate, Right? So here you see the original macro nuclei, those they're going to disintegrate. These are our new macro nuclei, and these again are micro nuclei that we formed, um, back here back here in this stage and basically thes are going to split up into a bunch of new cells. So we are going to wind up with it. We're actually only being shown to cells. We're actually gonna wind up with four cells from this because so I'm just gonna put like times too right here. Because in each of these cells, right, just clear some space and each of these cells we have to macro nuclei right here, here. And we also have to micro nuclei here, here, here and here. And we're gonna wind up with four cells at this point that each have one micro nucleus and one macro nucleus. And, um, again, these micro nuclei are going to be deployed at this phase again. So and then, of course, the cycle can repeat. So this is how silly it's reproduce sexually by exchanging these by first having their micro nuclei undergo my ASUs, then exchanging half Lloyd micro nuclei, having the new micro nucleus fused with the original micro nucleus and then undergoing a bunch of my toast sis to generate new macro nuclei and, um, and you micro nuclei and then all of those splitting up into new cells. So that is one way to introduce. Or that is one way that you Kerasiotes, um, will perform a type of sexual reproduction. There's many ways that that actually happens, and like we saw a PICO complex is where it gets kind of crazy. You're going between different organisms. Remember, all of this is really just to introduce more genetic variation into the, you know, descendants of these organisms that let's flip the page.
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Rhizarians and Amoebozoa

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theories. Erian's our last sub group of the S A. R. Clayton. These air mostly uni cellular amoebas that use pseudo podia for feeding. Now, radial arians contain a new internal silica skeleton like structure. And then they have these pseudo podia projections that they used for feeding on microorganisms. And you can see unexamined of radial arian here, this being like the main part of the organism with some sort of internal silica skeleton like thing. And then these are the suda podia that are projecting outward to feed on microorganisms. Now, forums have these calcium carbonate shells that you can see here, and these shells actually have little holes in them through which Sudha podia can emerge. Some of these organisms have cells that contain multiple nuclei. So hopefully you're seeing the theme here, right? Pseudo podia used for feeding last. We have the circus zones, and you can see an example of one right here thes our flag related protests. You can see the little flag yellow going right there. And, um I'm sorry. These are, um, Eva and flag related protests, and they feed with thin Sudha pods. Right? So the theme of this group is feeding with pseudo podia. Now, lastly, the last major group of you carry outs. Um, we're gonna talk about our deepest A contact, And this group actually includes fungi and animals. So it's not all protests, but there is a group of protests in here that I really do wanna touch upon. And those are the amoebas oa. So, up to this point, we've been throwing around the term amoeba kind of fast and loose. But it's worth knowing that amoeba just refers to organisms that use pseudo podia amoebas oa r amoebas that have in particular Loeb and tube shaped pseudo podia so you can see, uh, two example or a cup, rather a few examples of amoebas. Oh, here, um, these, uh, these particular organisms that you are seeing are actually slime molds. And, um, there they are depicting two different types of slime molds. So, believe it or not, this organism right here that you see, sometimes called dog vomit slime mold It's lovely name, lovely looking organism. And this is what's known as a plasma little slime mold. And basically, what this means is this big glop right here, right? This big yellow glop is actually one massive, continuous cell, believe it or not, and it contains thousands of nuclei. Um, if you are wondering, uh, it's not all one giant cytoplasmic compartment, um, thesis Els Air Act or this cell is actually made of many little micro smaller compartments. I should say it's not one massive, you know, continuous cellular interior, so to speak. It is compartmentalized, but technically, this is all one big, big old cell with a ton of nuclei in it, and they actually reproduced by forming these fruiting bodies. Now I'm going to get back to fruiting bodies in a second. We'll talk much more about fruiting bodies when we get on thio fungi in a later video. But I want to talk about the other type of slime mold the cellular slime mold, and these slime molds form their fruiting bodies by aggregating all the little cells. So here you can see, this is a fruiting body that is being formed, and all of these little teeny dots that you see in here there's so many I can't circle them. All right, all these little dots, you can see them coming together here and here and here, forming into this big aggregate. Well, all those little cells air for our coming together and forming these big aggregates of cells which, if we zoom out, form fruiting bodies and you can see this right here. These are the fruiting bodies, and that is how these slime molds they're gonna reproduce. They're going to reproduce from these fruiting bodies. The difference being that plasma little slime molds are just one continuous cell forming the fruiting bodies and the cellular slime molds are many cells coming together forming these aggregates to make the fruiting bodies. So that's pretty much all I have for, uh, the different types of protests. Um, I don't expect you to walk away with a thorough knowledge of any one particular type of protests. Really, This is just to show you, uh, kind of broad strokes. How? Um, diverse a group. Protests are right. That's kind of the point. I'm trying to drill home here. They're they're very there, quite varied and diverse in there, morphology and life cycles. And that's because again, it's kind of like the garbage are, you know, they like to think of it like the garbage dump group, because it's like basically, we're all you carry outs that aren't plants, animals and fungi get dumped into. So, um, you know, there's not really many unifying themes to them. And as you can see from all these different groups of organisms we've discussed, uh, they convey very, um, they can vary quite a lot in their form, function and life cycles. All right, I'll see you guys later.