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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.

  • 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

  • which is going to be this resistant structure where the spores are actually formed. It will

  • rupture and then we get this hiss as the spores are spread out. If you look at that, a bunch

  • of them together look like that. And a whole bunch of them together are going to look like

  • this. So this is a bread mold, zygosporangia that you're familiar with. And so basically

  • what happens if you leave some bread out, one of these spores is going to land on it

  • and were going to get the growth of this fungus. What's the fungus eating? It's eating the

  • bread because that's what they do. They're heterotrophs. And so can you remember those

  • five important phyla of fungi? Ascomycota. Basidiomycota. Chytridiomycota. Glomeromycota.

  • And zygomycota. And they're all just different types of fungi. And fungi serve a huge roll

  • on our planet. They breakdown material when it's dead and dying. They recycle those nutrients,

  • but they also form these symbiotic relationships with plants and algae. And I hope that all

  • is helpful.

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

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    Cheng-Hong Liu に公開 2021 年 01 月 14 日
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