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Protist is kind of an outdated term but you're still going to see it a lot in biology.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