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  • Hi. It's Mr. Andersen and in this podcast I'm going to talk about the protists.

  • Protist is kind of an outdated term but you're still going to see it a lot in biology. It

  • just means basically eukaryotic organisms that aren't plants, animals and fungi. And

  • we'll talk about those more specifically in the next few podcasts. But it contains cool

  • things like this paramecium right here or this plasmodium that causes malaria. So it's

  • an important group. But it's a massive group. It contains tons of different things that

  • probably aren't even related to each other. And so this is from the tree of life project.

  • Basically it's a pretty ambitious goal. But what they're trying to do is classify all

  • life on our planet. And you can find it at tolweb.org. But basically we are now into

  • the domain eukaryea, so these are things that have a nucleus. They have organelles. But

  • you can see that they're trying to break it down into all the different kingdoms, phylums,

  • classes. All the way down. And so there are some things in here that aren't protists.

  • And so I would say green plants would be one of those. Another thing would be the animals.

  • And then another thing would be the fungi. But everything else in here is what we classify

  • them into a group that's called the protists. And we're trying to figure out what are some

  • monophyletic groups within that. We have candidate kingdoms. But for now that makes your job

  • easier as a biology student because you don't have to learn a bunch of different types of

  • them. And so in other words we like to think of this as the biological junk drawer. So

  • just like in my house I have a drawer where I have scissors and tape and pens and glue

  • and all these things. Basically they're things that don't have a specific place so we through

  • them all in that drawer. That's what protists is. And that's why I put quotes around the

  • word phylogeny. In other words it's evolutionary history because we don't really know whose

  • related to whom. There are a few characteristics however that you should know of protists.

  • Number one they're eukaryotic. That means they have nuclei. They also have organelles.

  • They could be multicellular or unicellular. A lot of the ones we see in pond water are

  • going to be unicellular. But we can see massive protists as well. And then they're not going

  • to have true tissues. Or they're not going to have tissues in general. They're just going

  • to be a group of cells kind of working together. And so this kind of separates it from the

  • other big kingdoms that you do have to understand. Those are the fungi, the plants and then the

  • animals. And so basically they live in pretty much every part of our planet. And they fill

  • a number of different niches. They fill a number of different roles. And they have metabolism

  • that is just about as diverse as everything else. And so the two major groups are going

  • to be the photoautotrophs or the phototrophs. Basically they make their own food generally

  • using energy from the sun. So what's an example of something you might not think of as protist

  • is kelp. But we'd also find like this euglena here or this dinoflagellate which makes up

  • the crimson tide. All of these are taking energy from the sun. They're using chlorophyll

  • and they're converting that to energy of molecules, where they can break it down through cellular

  • respiration. But we also have a bunch of organotrophs. Those are feeding organisms so the plasmodium

  • that causes malaria is actually living in both the liver and the red blood cells. We

  • have trypanosomes. We have an amoeba that's going to feed on other protists. So these

  • aren't making their own energy. They're actually eating food and getting energy from that.

  • And so how do they reproduce? Well of course they have a bunch of diverse ways to reproduce.

  • Some do it asexually. Some do it sexually. Like this right here is a paramecium that's

  • simply splitting in half. So that's binary fission. But they also have these paramecium

  • will have conjugation where they can come together and share bits of their genetic information.

  • Some of them reproduce sexually. Some do both. This right here is one of my favorite organisms.

  • This is the slime mold. And you can see the slime mold here growing on a can. Basically

  • what they'll do is they'll have an asexual portion of their life. A sexual portion of

  • their life and then a social portion where they're just out cruising around. So they're

  • kind of like an amoeba. And so they, slime mold is insane. I think they have something

  • like thirteen different genders. And so it blends the line between animals and plants.

  • And it just is a taste of all of the different types of reproduction that we have in protists.

  • And they've got a great diversity. And so this paramecium is in a group of ciliates.

  • They're going to have these cilia around the outside. But we also have protists like this.

  • This is this volvox. A volvox is going to be a large colony of cells. But then they'll

  • have small colonies inside it. They are important as well. So the kelp forests in the ocean

  • are going to be protists. And then some of my favorite protists are these things. These

  • are dinoflagellates. Or excuse me, these are diatoms. Diatoms are actually converting silicon

  • into glass. And they do it at low temperature. And so if you've ever brushed your teeth,

  • hopefully you have, and that gritty stuff that you find within toothpaste is going to

  • be the bodies of dead diatoms or diatomaceous earth. And so again protists have a great

  • diversity. The big thing that you should remember is that they're eukaryotic, or eukaryotes.

  • And they're not plants, animal, fungi. And if you know that you're well on your way to

  • understanding protists. And I hope that's helpful.

Hi. It's Mr. Andersen and in this podcast I'm going to talk about the protists.

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Protists (Protists)

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    Cheng-Hong Liu 發佈於 2021 年 01 月 14 日
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