Name: 真菌 (Fungi)
Uploaded: 2021-01-14T05:24:05.000Z
Duration: 9 min 14 s
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Hi. It's Mr. Andersen and in this podcast I'm going to talk about fungi.

Fungi is a pretty diverse group. It's things that you're familiar with like a mushroom.

關係子句

But it's also things that are much smaller than that like a yeast which are going to

be single cell fungi. And they're also going to form sometimes symbiotic relationships.

So lichen for example is a symbiotic relationship between a fungi and then an algae. And so

not only do they breakdown and decompose material, but they're also going to serve another role.

Working symbiotically with both algae and then plants to allow them to function better.

And so basically if we look at their phylogeny. So this is the eukaryotes. So were going to

talk about things now that have a nucleus and have organelles. And you can find here

that here's our fungi. In other words when we try to classify all eukaryotes, we're going

to put them right here. If you look at animals, animals are going to be right here. And so

what does this mean? Well we're going to share more recent common ancestry with fungi than

we are with plants which are going to be way back here. Because we put green plants way

over on this side. And so we probably have more in common with a fungi, especially the

way we live our life than we do with green plants. But we're not directly related to

them. This is more in to the phylogeny of the actual fungi. And again we get this from

the tree of life project. And so you can see that we have this break off like this. And

there are monophyletic groups. In other words there's going to be some groups that you should

know because we know that these things all share common ancestry and they're one group.

And so there are going to be five of those. Chytridiomycota, zygomycota, glomeromycota,

ascomycota and then basidiomycota. And so these are ones that you do need to know because

they're monophyletic. And they're important when we're studying biology. But before we

get there let's get to the characteristics of fungi. Well they're eukaryotic. So they've

got a nuclei and organelles. They're heterotrophs. They originally were classified as plants

and you can see why. It almost looks like a plant. And they don't move. They don't run

around like animals. And they also have these root like structures that look like plant

roots. And so we used to classify them as plants, but they're not. They eat material.

And they're going to digest material. I'll show you some cool examples of that in just

a second. They have cell walls. So that separates them from us. Also the fact that they don't

move. And the cell walls are made of a polysaccharide called chitin. The exoskeleton of insects

are made from that similar structure. Most of the inside of the structure is actually

going to be filamentous. In other words it's made of filaments. And so this would be the

filaments in a mushroom. You can see these thin little filaments. You can see the cell

wall going around the outside of it. But they're not going to have any true tissues. In other

words they're not going to have, for example, a muscle tissue or nervous tissue. It's just

going to be a group of these hyphae they call these. That's what these filaments are called,

over and over and over again. And so even if we were to look in here to these fruiting

bodies of these mushrooms, we'd find that they're hyphae just packed together really,

really tightly. Or if we were to look at the roots of them, those are going to hyphae absorbing

nutrients. And so those are some of the characteristics shared by all fungi. They're all heterotrophic.

And so if you see one growing out of this tree or this rotting tree, they're digesting

the material inside there and they're eating. And you can see here that this mold, which

mold is kind of a term that just means fast growing fungi, you can see this mold is breaking

down this fruit. And if you've ever had athletes foot you've been infected by a fungus as well.

And so this right here is a fungus growing in between the toes. And it's hyphae will

actually grow into the tissues of the person's foot. It secretes an enzyme. Then it digests

that material inside. And it's really painful because it's starting to digest the nerves

on the outside of the foot. And one of my favorite fungi of all is this anthrobotrys.

Basically what they do is you can see the hyphae that they're growing here. But they'll

make these tiny little rings. And then when you have a worm like this. This is called

a nematode worm. Basically if the nematode worm starts to swim through this ring, it

will cinch tight on the nematode worm. It will grab a hold of it. And then it's going

to digest it from the outside in. And so this is an animal eating fungi. And so what could

be much cooler than that. How do they reproduce? Well they do reproduce a lot of the time asexually.

And so when you have mushrooms just continuing to grow out and out and out and out. And they

can grow relatively quick, that's going to be asexual. But then they can also have a

sexual phase as well. And so the spores that come out of a puff ball like this are usually

going to be asexual spores that can spread to an area where there's a little bit of water,

some food and they can start growing. But there's also sexual portions. So these were

formed through a sexual process. If we look at this mushroom right here, basically what

you get are, this would be a basidiomycetes. Basically you're going to have spores that

fall down. You get the growth of a new mushroom, but then we can have sexual reproduction producing

more spores. And so there's a variety of ways they reproduce. Like I mentioned at the beginning,

there are five important phyla that you have to know when it comes to studying fungi. And

I classified them from A to Z. This is just a quick way that I remember it. So we've got

A, B, C and we've got Z over here. So we go from A to Z. A, B, C and then we've got G

in the middle and the G can stand for um, Golly, aren't those fungi cool? Because these

ones are going to be really cool in just a second. And so let's go from A to Z. So the

first ones are the ascomycota. Ascomycota, the asco or the ascus, that's what ascus means.

It means cups. So ascus means cup fungi. Or sac fungi. And you can see right here this

is that sac. And then the spores are going to form on the inside of that. And that's

why we call it the ascomycota. Why are these important? Well this is my favorite fungi

of all. This is the morel. We like to go hunting them in the spring. They taste delicious but

they're really hard to find. You're looking right here at the sexual portion of that.

But you can see these sacs on the inside. Or the sac right here. But ascomycota are

also important. So penicillin is a fungus or an ascomycota that is going to make a lot

of the antibiotics that we have. And so they're important for that. If we look at basidiomycota

is the next one. And so that's the B. Basidio comes from the word basidium, which means

club. And you can see that on the underside of a mushroom they're going to have these

little gills. But if we zoom in closer we're going to find these club like structures.

And each of those club like structures is going to form spores. We'll have four spores

that are found on this basidium. And that's where the name basidiomycota comes from. It's

club fungi. And so what are the big ones? These are going to be the mushrooms that we

think of when we think of fungi. Those are going to be basidiomycota. If we look at these

two together sometimes we would say these two share common ancestry, ascomycota and

basidiomycota. And we sometimes call these the higher fungi. What's next? Next is the

C. So that's going to be chytridiomycota. And these are going to be sometimes referred

to as the chytrids. These used to classified as protists. And the reason why is that they

have a flagellated stage where they'll actually swim around. We now know that they're true

fungi. You've read about these in the news because we've seen on the planet huge increases

in deaths of frogs. And a lot of those are related to chytrid fungi that are infecting

the frogs. Alright, let's go to the G then. So the G stands for the glomeromycota. Glomeromycota

are very important because what they'll do is they form a symbiotic relationship with

plants or a plant symbiosis. So what we have are these mycorrhizal relationships. And so

this right here is the root of a plant. But you can see the fungi growing inside it. And

almost all plants, in other words every plant that we look for has these relationships between

the glomeromycota and their roots. What does that give them? Well that gives them increased

surface area and it allows them to take in more water. And then they give these fungi

a place to live. And so it's a great relationship for both the fungi and for the plant. And

then the last one is going to be the zygomycota. Zygomycota, its name comes from the zygosporangia