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Biology: Protists: Alveolata and Stramenopila


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About this Lesson

  • Type: Video Tutorial
  • Length: 15:02
  • Media: Video/mp4
  • Use: Watch Online & Download
  • Access Period: Unrestricted
  • Download: MP4 (iPod compatible)
  • Size: 162 MB
  • Posted: 07/01/2009

This lesson is part of the following series:

Biology Course (390 lessons, $198.00)
Biology: The Evolution of Life on Earth (34 lessons, $64.35)
Biology: Protists and the Origin of the Eukaryota (2 lessons, $4.95)

Taught by Professor George Wolfe, this lesson was selected from a broader, comprehensive course, Biology. This course and others are available from Thinkwell, Inc. The full course can be found at http://www.thinkwell.com/student/product/biology. The full course covers evolution, ecology, inorganic and organic chemistry, cell biology, respiration, molecular genetics, photosynthesis, biotechnology, cell reproduction, Mendelian genetics and mutation, population genetics and mutation, animal systems and homeostasis, evolution of life on earth, and plant systems and homeostasis.

George Wolfe brings 30+ years of teaching and curriculum writing experience to Thinkwell Biology. His teaching career started in Zaire, Africa where he taught Biology, Chemistry, Political Economics, and Physical Education in the Peace Corps. Since then, he's taught in the Western NY region, spending the last 20 years in the Rochester City School District where he is the Director of the Loudoun Academy of Science. Besides his teaching career, Mr. Wolfe has also been an Emmy-winning television host, fielding live questions for the PBS/WXXI production of Homework Hotline as well as writing and performing in "Football Physics" segments for the Buffalo Bills and the Discover Channel. His contributions to education have been extensive, serving on multiple advisory boards including the Cornell Institute of Physics Teachers, the Cornell Institute of Biology Teachers and the Harvard-Smithsonian Center for Astrophysics SportSmarts curriculum project. He has authored several publications including "The Nasonia Project", a lab series built around the genetics and behaviors of a parasitic wasp. He has received numerous awards throughout his teaching career including the NSTA Presidential Excellence Award, The National Association of Biology Teachers Outstanding Biology Teacher Award for New York State, The Shell Award for Outstanding Science Educator, and was recently inducted in the National Teaching Hall of Fame.

About this Author

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Are you guys still there? Have you run out of the room because you just can't stand to hear any more about those protist things? Well, hang in there, because let me tell you, I may not sound like a protist fan to you, but protists--one thing I want you to understand is that there is nothing more diverse than protists. They have filled every available niche imaginable in their own little group. If you were an alien landing on this planet from outer space and you based it simply on the number of species, you would say this is a protist planet, because they rule in terms of just sheer diversity.
And so where have we been here? Well, where we have been is we've realized that, once again, three domains--bacteria, archaea, eukarya, and that indeed what has happened in the eukarya is a common ancestry throughout, and the common ancestry first had a couple of out groups, the archaezoa and the euglenozoa, and right here it seems to be at least what our bio-informatics and our bio-systematics is telling us, seems to be a key forking place for the evolution of life on this planet. Why? Well, you know, one way to look at that, if you realize that what I'm about to draw is not going to be like a time type of thing, but a lot of systematists think that the following happened. That if we picture some kind of primitive down here, and our very first branch was the bacteria, and later on in time came the archaea, and then came this group called the protists, that we can make a very strong case that the mother of all organisms on the planet, indeed, were the protists, because from there came plants, animals, and fungi. And therefore, one theme I hope you have heard over and over again is the conversion from a uni-cellular to a colonial to a multi-cellular situation had to have happened right here at the protist stage. Let me tell you, if that stuff isn't exciting, you've got to be like a mathematician or something.
Here we go. Well, at this fork-remember, we came up with fungi, animals, and plants from this common ancestor, but we want to talk about the rest of the protists-what used to be a kingdom. And so we want to move-and I'm going to put another A right here. What does that A stand for? That A stands for the alveolata. To me that actually sounds like some kind of drink you can get in a coffee shop. I'd like an alveolata, please. what the alveolata have, they all have something in common. I've got to tell you this, because wait until you see what's in the alveolata. What the alveolata have is they have these structures called "alveoli kinds of things," and they are membrane cavities under the cell's surface. They all have them. We're not sure what it does, but they all have them.
Now, once we've done that and once we've looked at some of the DNA evidence, we take groups that used to be on opposite ends of the spectrum and we say, "Whew! We've got to put these together in this new kingdom--this new candidate kingdom called "alveolata." And what are these things? Well, let me show you the three groups that would go in here. First of all, one you may have heard of--the dinoflagellates. Dinoflagellates have been, in many ways, the bane of mankind for millennia. And the dinoflagellates are autotrophic-they make their own food-and they have a strong concentration of a photosynthetic pigment called xanthaphylls. Xanthaphylls is a red photosynthetic pigment, and these live in the ocean.
Have you ever heard of red tides? In fact, if any of you live in tropical areas and you're fisher people, you know that one of the things you don't do is eat top of the line predators on coral reefs. Do not eat a barracuda. Why? For example, one of the dinoflagellates, whose genus name is Pfisteria, which causes red tides, kills millions of fish. But when it's not in this blooming stage it's still out there and small fish eat it, and then bigger fish eat the smaller fish and bigger fish eat the... And what happens is you get this concentration of toxicity in the top of the line predators, and their meat can be poisonous. So you don't eat top of the line predators because of dinoflagellates. Dinoflagellates-they're not real good things.
Oh, one dinoflagellate that's kind of cool is one called a zooxanthellae. A zooxanthellae lives inside of corals. A zooxanthellae is a symbiont in that coral. It's mutualistic, and it turns out that coral polyps have these living inside of them, which is why coral polyps are green, and the zooxanthellae actually do photosynthesis for that coral and provide it with food.
One of our environmental disasters we seem to be looking at is the death of the coral reefs because of coral bleaching. Apparently, the corals nowadays, and we don't know if this is cyclical or because of something like global warming, but the corals all over the world are spitting out, literally, their zooxanthellae and dying. And your children may never see a living coral reef, and we're not sure why.
Okay, dinoflagellates-here's another one. Apicomplexans. There's enough to give you a complex, isn't it. Apicomplexans. All right. That's called protist humor. What they have is an AP complex, which makes it a great name for them. An AP complex, and an AP complex is a specialized structure that's made for penetrating. These are parasitic. These are nasties. And one of these parasites was near and dear to me for a few months back when I was in the Peace Corps because it gave me a disease called malaria.
Let me tell you a little bit about malaria. This is just one of those great protist stories that I have to share with you--or should I say "an apicomplexan story" I have to share with you. Here is the anopheles mosquito. The anopheles mosquito is a mosquito found in tropical areas, although they used to be found as far north as New York State and Ohio. Malaria, indeed, which is what I'm about to tell you about, was common in those areas, 100, 200 years ago. Now, I'm going to come back to this diagram, but I want you to see that there's something living in its gut, something swimming.
Let's talk about vomit. When a mosquito bites you it vomits--it spits--but vomit sounds so much more dramatic--under your skin so that your skin won't clog and get its nose stuck in your skin. I mean, that's very inconvenient. And so what it does is it puts this anticoagulant in you and kind of upchucks the contents of its stomach. Now, if this mosquito happens to be infected with this organism called "plasmodium," plasmodium then gets vomited into your system, where it takes up residence in your liver and goes through several stages of its lifecycle. But here's the thing--one stage of its lifecycle infects your red blood cells and it hides out there, so guess what? You can't fight it. You can't find it and you can't fight it.
So you're like, "Yeah, okay, so I got bit by a mosquito." Then a few days later they all burst out of the red blood cell and they infect other red blood cells and then they hide again, and then they burst out again, and then they hide again. Every time they burst out you've got more and more of them. And guess what you get every time they burst out? An immune response. A fever. And that's why when you get malaria--burst out, fever, get real sick, go away, I feel better. Burst out, fever, I get real sick, and then it goes away. And eventually it can get to the point where malaria kills you. But that's not much of a life cycle, except watch this. You get bit by another mosquito who becomes the vector. And now it gets very cool. This parasite is so highly adapted that it can parasitize mosquitoes, too, and literally it has sexual reproduction inside the gut of a mosquito and I guess that's better than having sexual reproduction inside of me, so I guess I'm better off than the mosquito. The thing goes through sexual reproduction inside of the mosquito and then the mosquito once again vomits out the little young, and the next person gets infected. How's that? Is that cool? See, protists aren't all bad. Well, that's not a good thing. But that's fascinating.
Oh, ciliates, the third group. Remember, we had dinoflagellates. We had Apicomplexans, and now ciliates. Ciliates--what can I say about ciliates. You guys all know about ciliates. There's your typical ciliate. Remember that ciliates have their bodies--I like to picture these things as footballs because they're three-dimensional and they've got cilia all over their body, and their swimming through the water, and your friend and mine, the paramecium, is a ciliate.
Now, good God, think about this. What do we have all in the same group? Dinoflagellates with their two flagella, plasmodium, a parasitic apicomplexan, and ciliates. Before they were like, whoa... Now, they're all in the same kingdom. Why? Because of what systematics and bio-informatics is telling us about these things.
Okay, next group--S. This is an interesting name--stramenopila. A real "planty" group, if I dare say this. We have a group here called "diatoms." Diatoms are the single most common cell in all of water. It is at the base of almost every aquatic food chain that exists. Everything depends on diatoms to live. They are very bizarre. Their outer shell is made out of silica--glass--and they swim, but nobody really knows how. Look at this picture of diatoms. How beautiful are these things?
And then a bunch of algae--golden algae. Golden algae are golden because of the pigments, and some of these are actually heterotrophic. Some of them are not photosynthetic at all. Some are; some aren't. Probably the most difficult choice was to put these in here. There's one even weirder I'm going to put over here--the brown algae. Why did we put the brown algae in there? Well, the brown algae used to be called "seaweed," and it's multi-cellular. But nevertheless, because of the evidence and the chloroplast evidence, and the pigment evidence, and the DNA evidence, we're finding out that these three things go together. And the most bizarre of all in my world, the water molds. Now, you can tell me these are supposed to be fungi, but you're wrong. Mildew--these things are actually going to be protist now, or what used to be called protist. Obviously they're going to be in the stramenopila.
These creatures--now why aren't they fungi anymore? Come on, they're molds. Aren't these supposed to be fungi? But when you look at their cell wall, their cell wall is made out of something called "cellulose." Cellulose is not what a fungal cell wall is made out of, so you have to use the biochemistry and put them right here. Some of you may have been affected by mildew. Your clothes get mildewy, your books get mildewy. The Irish potato famine was caused by mildew. So the stramenopila...
And last but not least. Well, you know what? Let's go right here with the green algae. Now, this is very, very interesting. And what we're going to put right here used to be called the chlorophyta, and the chlorophyta, notice the plants are branching off there. There's a lot of argument as to whether these should even be considered plants or not. There's over 7,000 species of these things, and they have many, many similarities to plants.
I've just got to tell you one more thing. Do you feel like something's missing here? Think of all the protists that have been your friends over the years. Does this look like anything you've ever seen before, this single-celled creature, the most famous protist of all, the amoeba? Where is he? Why didn't we put these things in there? Here's why. I'll tell you why. I feel very strongly about this. What is this thing? This is a slime mold. You want to know why we don't know where to put this thing and things like the amoeba? Watch. This thing starts out as an amoeba group of cells. They kind of glob together and form an organism. The organism, like a slug, crawls along the road, and it grows into a fruiting body where cells pop off and form more amoebas than can go that way or form sexual reproduction. You tell me where to put that. Somebody is going to pretty soon because we've got to get that thing in there with the protists.
So I have to tell you, there's a lesson to be learned here. Remember, biology and evolution, and indeed, our understanding of biology, is a work in progress. Ultimately, the DNA evidence will tell us where to put all of these things, but the protists, what a great kingdom to take a look at systematically, because it shows us more than anything how incredibly diverse single-cellularity can be, and where, perhaps, the origin of multi-cellularity came from. I wish I had about three more lectures to talk to you about protists, but we've got to move on.
The Evolution of Life on Earth
Protists and the Origin of the Eukaryota
Protists: Alveolata and Stramenopila Page [3 of 3]

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