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Post by Bryan Cardella on August 4 at 08:24:05 AM

Dinoflagellate actually means "whirling tailed-one"
(yes, "dino" also means "terrible" like in the word dinosaur, but there is an alternate meaning too!)


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  • Intro 0:00
  • Kingdom Protista Basics 0:04
    • Unicellular and Multicellular
    • Asexual and Sexual
    • Water and Land
    • Resemble Other Life Forms
  • Protist Origin 2:04
    • Evolutionary Bridge Between Bacteria and Multicellular Eukaryotes
    • Protist Ancestors
  • Protist Debate 4:18
    • One Kingdom
    • Some Scientists Group Into Separate Kingdoms Based on Genetic Links
  • Plant-like Protists 6:03
    • Photoautotrophs
    • Green Algae
    • Red Algae
    • Brown Algae
    • Golden Algae
    • Dinoflagellates
    • Diatoms
    • Euglena
  • Euglena Structure 10:39
  • Ulva Life Cycle 12:08
  • Fungi-Like Protists 15:39
    • Heterotrophs That Feed on Decaying Organic Matter
    • Found Anywhere with Moisture and Warmth
  • Cellular Slime Mold Life Cycle 17:34
  • Animal-like Protists 21:45
    • Heterotrophs That Eat Live Cells
    • Motile
  • Amoeba Life Cycle 25:24
  • How Protists Impact Humans 29:09
    • Good
    • Bad

Transcription: Protists

Hi, welcome back to, this is the lesson on protists.0000

With Kingdom Protista, it is the official name, let us go over some basics.0006

What makes them unique, why are they in this kingdom of life?0009

This kingdom contains eukaryotic organisms that do not have specialized tissues.0013

You are going to see that a lot of these resemble animals, plants, fungi,0017

but they do not belong in those kingdoms for various reasons.0022

Usually, evolving around, the lack of tissues and specialization with the cells.0024

Some protists are unicellular, actually a lot of them are, and others are multicellular.0028

We cannot say that the reason why they are not animals is they are all single celled.0034

There are some that actually do have multicellular versions.0038

Some species are completely unicellular, others actually can be multicellular. 0041

Some are asexual, in terms of how they reproduce, they just divide like bacteria do.0047

Some are sexual, others can actually do both.0053

I will give you an example, later on in the lesson about one that can do either, depending on the conditions,0056

depending on whether not there is another organism there that can mate with it.0060

Mostly found in water, that is traditionally true about protists.0065

They are highly dependent on water to survive.0068

However, others can get by on land.0072

Not just like a puddle, or a stream of water, I mean that in soil, you can find protists.0074

But they do typically have to have a damp environment, moisture needs to be there in the soil for them to survive.0082

It would be less likely that you would see them in a desert kind of environment.0088

They resemble but are not categorized with other life forms, as I mentioned earlier.0092

Because of this, they are described as plant-like protists, fungi-like protists, and animal-like protists.0096

Here is a wide variety here, we will go over a lot of these later on in the lesson.0103

This right here is a classic protists known as perimysium.0109

There are lots of different members of that genus, perimysium.0112

You will see this word come up again.0116

The origin of protists, protists are like an evolutionary bridge between bacteria and multicellular eukaryotes.0125

Keep in mind that bacteria are prokaryotic, they do not have nuclei, membrane bound organelles, but eukaryotes do.0132

The initiation of protists, we can thank endosymbiosis.0139

We can thank that occurrence that led to this kingdom.0143

The first eukaryotes on earth could be called the earliest protists ancestors.0147

Technically, they are also our ancestors, we are related to protists.0152

It is a very distant relationship but definitely we came from a single celled being a long time ago.0156

If we were like to map out, like here is the first cell on earth.0164

From there you get bacteria, archaea and eubacteria.0171

And then from out of that, once you have endosymdiosis occurring, you get kingdom protista,0183

which is what this lesson is all about.0197

From there, you get plants, you get fungi, and you get animals.0201

How do you get actually from this purple area, having these single celled eukaryotic beings,0227

to getting multicellular kingdoms that have highly specialized tissues in their bodies.0233

There are a lot of theories about that, it really had to do with early on examples of cells coming together,0239

cooperating, taking on different roles, and order them to lead to like the first simple animals, 0246

the first simple fungi, and the first multicellular simple plants.0254

I want to think of a protists debate, depending on what textbook you look in 0260

or what sources you look up on the internet, for instance, you are going to see conflicting theories or reviews on this.0263

Traditionally, protists are grouped in one kingdom.0270

When I took high school, it is very common, kingdom protista.0273

A lot of times in textbooks today, you will see protists broken up into multiple kingdoms.0278

The reason why is because, they begun to separate them into their own kingdoms 0283

because it is based on genetic links, that puts certain protists into evolutionary branches with each other.0288

You could have two protists that on first glance when you look under a microscope, they do not look that similar.0293

But when you compare their DNA, there is a lot more in common in terms of the DNA than it appears to be, because looks can be deceiving.0299

They probably put those two in a very close relationship, 0306

than compared to others that have slightly different genetics or maybe very different genetics.0310

They think they are from a different lineage.0315

The split between those groups came early on.0317

The reason why, in my opinion, it does not exactly matter that we do that here in this lesson is,0320

I’m going to introduce a wide variety of protists to you.0326

Whether or not we break it up at the kingdom level or talk about groups of protists underneath or within that kingdom.0329

To me it is not that significant of a difference.0337

As long as we really understand the plethora of protists that are on planet earth.0340

This is actually an example of a protista called stemtour, really cool looking protista.0345

You can see there is this crown of cilia that helps it bring food in.0350

You can see the size here, 200 micrometers is that amount.0356

This is microscopic.0361

The first group I’m going to talk about is the plant-like protists.0365

These resemble members of kingdom plantae, by they are not in kingdom plantae.0368

Because of that, they are photoautotrophs.0372

They use light to make their own food or to create their own energy source, they are doing photosynthesis.0377

Mostly found in oceans, lakes, and rivers.0384

It is possible you can see these on land.0386

Typically, if you do see them on land, you are seeing them near a major water source.0389

Yes, the oceans, a home to quadrillions of algae cells.0395

Green algae is definitely the most abundant type of plant-like protists on planet earth.0403

A lot of them are single celled, others are multicellular.0410

Here is an example, volvox is this ball of photosynthetic cells.0413

It can make little tiny babies that it releases, once they are ready to go.0421

Very pretty looking protista, you have to use a microscope to see that.0427

Red algae also known as rhodofida, the red algae, usually there is a bunch of red pigment.0432

That makes sense, that is why they are red algae.0445

Some of them are single celled, others are multicellular, look kind of like a very thin red leaf, in a sense.0448

If you got sushi, if you have the seaweed that they use to make sushi, that comes from a type of red algae.0455

It gets dried out over time and actually looks black, typically, after it is no longer alive.0461

The sushi rolls, they use red algae.0470

Brown algae, kelp is the most common example of that.0476

It is nicknamed feophyta.0481

Feophyta, sometimes there are single celled versions but kelp, the largest protista on planet earth.0487

Sometimes we are talking several meters from top to bottom.0495

Usually it is at the top, the surface of the ocean, and it can go down quite a ways, 20 feet sometimes.0499

The top is typically buoyant because of these little gas bladders it makes.0508

In terms of specialized tissues, it is on the course of really having what we call plant like tissues.0515

It does not have true roots, it does not have true leaves.0522

They have like these blades that are a little bit simpler than an actual leaf.0526

They do photosynthesis in those little gas bladders filled with gas, given some buoyancy.0531

The closer they are on the surface, the more sunlight they can absorb to make food.0536

Kelp, as you can see in this picture, supports a wide variety of life forms.0541

There is a lot of animals that depend on kelp forests in the ocean.0545

Golden algae also called chrisophyta, sometimes they are single celled, sometimes it is multicellular.0549

They are also known as chrisophytes.0557

Dinoflagellates, this is actually an example of dinoflagellate, that little will model there, zoomed into it.0559

Dinoflagellates pretty much means ancient tailed ones, they have multiple flagella.0566

They can spin around, moving their flagella, very interesting protists that do photosynthesis.0575

Diatoms, I will show you a picture later on in the lesson of diatoms that are photosynthetic 0581

but have these really interesting shells called tests, like the word, like an exam, tests.0589

They have a shell that protects them.0599

When they die and leave over that shell that is typically made of silica, calcium carbonate, that stuff can be use for filtration.0601

That is something that humans can use for our needs but they are quite plentiful in the ocean.0612

Finally, euglena is another classic example of a plant -like protists.0617

It has a tail, has a flagellum that can move in whip like motion and they do photosynthesis.0621

Actually, they can take in nutrients too, which is very interesting that a photosynthetic organism could eat stuff as well.0627

In the next slide I’m going to show you a picture of what euglena got in it.0634

Here is the euglena structure, you can see that here is that prominent flagellum.0640

They have a stigma also known as an eye spot, that is light sensitive.0647

They are not actually seeing shapes and actually seeing color anything like that, but they are light sensitive.0651

They can tell that lights over there and they will swim towards it.0657

It makes sense, that particular adaptation allows them to do more photosynthesis,0660

the more light they can absorb and the more carbon dioxide they can enjoy under the water.0664

Here is the chloroplast, that helps with photosynthesis.0668

Nucleus with the nucleolus inside, contractile vacuole, this is actually a common structure you can see on a lot of different protists.0674

The contractile vacuole will take on water and squirt it out when needed.0683

Let us say this particular euglena cell is in some kind of lake.0688

There are parts of lake that have a higher salt content and other parts that are lower salt content.0695

If they go in the part of the lake with a lot less salt in the water, they might take on more water because of osmosis going inside of their cell.0700

They do not want to burst, they do not want to explode from that taking on water.0708

The contractile vacuole expand and hold the water in it temporarily, excrete it out at the right moment.0711

Polysaccharides are going to be made, as a result of accumulating glucose for photosynthesis.0719

They can save those for rainy day, literally.0725

Life cycle of a common plant-like protists called ulva, that is the genus name for this particular type plant-like protists.0729

It is a multicellular green algae.0737

It can do sexual reproduction and the amazing thing is one organism can make sperm and egg, and they can fertilize each other.0739

Or the sperm and egg can fertilize another neighboring example of this.0751

Up here, this is known as, you can call it the sporophyte generation, that term will come up again with the plant kingdom.0756

It is 2N meaning it is diploid, it has two copies of the chromosome.0768

When it undergoes meiosis, it will make haploid spores.0772

Here is meiosis, you actually get little, here is that N generation, little spores being made.0783

These spores with the haploid number of chromosomes,0795

then undergo mitosis to make a haploid multicellular structure, that will look very similar to what you are seeing up there.0799

They are usually smaller versions of the sporophyte.0813

They actually have female versions and male versions.0816

These are still considered N, in terms of the haploid number.0821

And then, this haploid structure, that haploid structure, they will make little flagellated spores.0825

They will be female spores and male spores.0834

It is an interesting example of how you can have female cells with flagella, with little tails.0844

We are not used to seeing that.0849

Because with the animal kingdom and the plant kingdom, if the gamete have tails, 0851

we typically associate them with the male side of things.0856

The female is just sitting there and waiting, for that particular cell.0858

This is a case where they both can have tails.0862

When they combine, or actually going to go back into the diploid.0865

They come together through fertilization.0874

There is the haploid again.0885

And then, this haploid structure will germinate, it will grow in size a bit.0886

Eventually, once again multicellular fully developed diploid sporophyte.0895

And then, we can call this segment, the green part that I have drawn here, 0903

the gametophyte generation which is typically associated with haploid structures.0906

Let me actually write that for you.0912

Like I said, with the plant kingdom, those terms sporophyte and gametophyte will come up again.0920

This is how you can get reproduction of a plant-like protists.0925

Other plant-like protists have a variation of this, might be a little bit different.0929

You have a lot of variety of kinds of reproduction with kingdom protista.0933

Now, the fungi-like protists, these protists are heterotrophs, they are not autotrophs like we saw in the plant-like protists.0940

They feed on decaying organic matter.0946

Sometimes they are feeding off of organisms living on them or within them, that is not as common.0949

Typically, they are breaking down dead stuff, dead bodies, little bits of things that will formally alive.0957

They are found almost anywhere where there is moisture and warmth.0965

The easiest place where you can find these is, if you have not cleaned your shower in while, or your bathtub, they may be there.0968

They maybe those little spots, black or white spots that we would see on the shower curtain 0976

or in the grout of the tile, because they actually can come in through your water supply.0982

Some examples, plasmodule slime molds and cellular slime molds.0989

Those are great names, they are slimy looking.0992

You can find terrestrial, here is an example of a slime mold, part of them that it is growing in grass.0997

It is feeding off of something that died there, maybe lots of things that have died there over time, insects, etc.1004

Water molds and downy mildews, here is an example of a water mold and here is an example of mildew.1011

This is an example where it is actually growing on a living structure.1019

It is actually growing on a leaf that is still alive.1023

If this does not get taken care of, it can lead to the death of the plant, over time.1026

If it is killing off its photosynthetic ability in the leaves.1031

You can have downy mildews and powdery mildew.1035

The cellular slime mold lifecycle, it is kind of interesting how it develops.1056

Let me draw it out for you.1061

Let us start with, it is like a mass of cells that could be feeding off of like a dead tree, like a log.1065

This is just a giant mass of cells that have gathered together and safety in numbers, to get it done.1076

Occasionally, you will have just a part of it breaking off, when it is not as widely developed or as extensive,1087

you can have just as part of it also take on this slug like characteristic.1095

Slug like version, we are going to call it.1103

It looks like a slug, it looks like a shell of snail but it is not.1107

It does not actually have a head, it does not have developed organs, it does not have eyes, or any of that stuff.1112

It just looks like a little slug, we are talking really tiny like barely visible, it is very tiny.1117

It will actually crawl, it will actually slither as this unit.1124

The amazing thing is that, when the conditions are right, it will make just kind of this smaller stationary mass 1129

and then it will grow a fruiting body out of the top.1137

Let me adjust this briefly.1143

The slug will stop and then it will start to have part of it start growing up and that is how you get to this,1145

that is how you get to this part growing which is known as the fruiting body.1154

Fruiting body, that is a term that is used in a lot of different organisms.1165

You are going to see the term fruiting body with kingdom fungi, not just fungi-like protists like we are seeing here.1169

The fruiting body, you have development within here of spores.1177

These spores are released from the fruiting body.1182

These spores can develop into these little units that hatch an amoeba like cell.1196

Here is the spore with an amoeba coming out of it.1204

Here is another little spore with an amoeba crawling out of it.1210

Amoebas, I’m going to tell you more about traditional amoebas that are animal-like protists,1214

a different species but this particular fungi-like protists can take on that amoeba like cell shape.1219

We are going to call them amoeba like cells.1227

And then, these amoeba-like cells, they can gather together body up.1233

Eventually, it can go back to this, this huge mass.1249

A lot of this is dependent on the conditions.1253

If there is enough moisture in organisms feeding off of, it will get to this stage, this huge mass.1255

If moisture goes away, the food source goes away, a lot of this could die off.1263

As long as they can retain a little bit of themselves, those cells can had this happen all over again.1268

There is a point in time when you can have sexual reproduction.1275

This is really a way that it can asexually just make more copies.1280

Through sexual reproduction, you can actually have these cells at this part of the cycle up here, undergo meiosis, make haploids.1283

We are talking different cellular slime molds making haploids then join it together1294

to make a new diploid that leads to this mass forming again, it can start all over.1298

Animal-like protists, this is the last category that I’m going to teach you about.1306

These are protists that are heterotrophs that are eating live cells, typically.1309

That is what makes them resemble animals, animals that are predators that feed off of other life that is alive.1314

Many of them are motile, we see a lot of them moving themselves through the water, it is a very common thing.1322

Here we have different, in this picture, amoeba forms.1328

This is a very old drawing, this drawing to our knowledge is over hundred years old.1331

People looking in microscopes for decades have been fascinated by amoebas and the different shapes they can take on.1338

Like I said, many of them are mobile, and zooflagellates is an example of an animal-like protists that has flagella.1346

Notice it is not dinoflagellates, that was plant-like protists.1354

The word zoo like zoology, the study of animals, zoo means animal with a flagella on it.1357

Amoebas, they make these little pseudopods or pseudopodia which pretty much mean fake feet or false feet.1364

That is what you are seeing here, these little out pouching, you could call them, of the plasma membrane.1379

This has to do with the altering their cytoskeleton, altering how microfilaments, 1386

part of the cytoskeleton, are pulling or letting go on the plasma membrane.1390

And they make these little, almost look like they are crawling through the water with what looks like legs, but they are not.1394

Sporozoans, this is another category.1402

With sporozoans, you would see actually a lot of variety.1405

An example is plasmodium, plasmodium is actually the organism that causes malaria.1411

That particular kind of protists would be inside of the mosquito, usually a mosquito biting you, 1426

getting blood from the capillaries in your arms or wherever its landed.1434

You have some exchange of fluid from you to the mosquito, vice versa.1439

The plasmodium inside the mosquito ends up in your body, goes to your liver, uses your liver to make more of themselves.1444

There are units that get into the blood flow going to liver and then out of your liver.1452

In a certain stage of the lifecycle, they inhabit your red blood cells.1459

If untreated, malaria can kill a person.1462

The amazing thing is mosquitoes that do not have malaria in them, 1465

if they bite a person with malaria then it can get inside of the mosquito body.1471

It is this cycle of mosquito to human, human to mosquito, and so on.1476

Malaria, if untreated can be deadly because of that plasmodium effect on your blood.1480

Ciliates, these are animal-like protists that have cilia, little hair like extensions coming out of the plasma membrane that help them move.1486

The classic example is perimysium which is right here.1496

It is tough to see but there is a ring of cilia all around that.1499

You even cannot see also the tons of organelles inside of the perimysium.1505

By the way, this picture is showing what that malaria protists does to your blood cells.1508

All of these little reddish circles goes to your blood cells or erythrocytes that had been inhabited by the plasmodium that causes malaria.1515

The amoeba life cycle goes something like this.1526

There is a couple of options for amoebas, they traditionally do asexual reproduction.1528

There is some evidence that perhaps the ancestors of amoebas actually had sexual reproduction.1535

We see a lot of variety with amoeba genetics today.1542

The theories that they originated probably from a sexually producing single celled being.1547

As far as we know, there is not really a sexual reproduction that is observable in amoebas of today.1553

Here are two options for the adult amoeba, if you can even call it an adult.1560

Single celled, one option is binary fission, the other one is multiple fission.1565

Binary fission, we usually see the word binary fission associated with bacteria but here same term.1572

Binary fission is when this amoeba will actually just make two.1588

Here is an amoeba, it will take in its pseudopods, it does look like what a bacteria do.1598

It just copies its DNA, it does not take as long as mitosis.1606

This will divide into daughter amoeba cells.1611

Here are the daughter cells.1630

And then, another way it can make babies is multiple fission.1631

Here is that amoeba that takes in its pseudopods, and then, it will form this cyst.1645

The terms cyst is for, when a cell, it looks like it is going dormant, it makes this thick coat around the outside, this cyst like form.1652

Inside of that cyst, you will actually get development of a lot of cells through mitosis.1664

Here, the term binary fission is not used because it is not making just two binary 2, double.1680

This is making multiple daughter cells.1686

You can see that, it is like taking that space, the cytoplasmic space that the original amoeba took up.1697

It is just giving that up, making tiny little daughter cells.1705

Eventually, it ruptures, it breaks open, and releases the tiny little cells which can grow, 1709

as they take on nutrients and make more cell parts.1720

Obviously, from the multiple fissions, you get a lot more daughter cells with this kind of reproduction than with this one.1730

Perhaps, what stimulates the amoeba to go one way or the other is the amount of nutrients that are available.1739

If there is a lot of nutrients around, why not do what is on the right here, why not make more babies if you can.1743

How protists impact humans?1750

You might not think they are around you a lot, but they really are.1753

Some good things, oxygen production, you can thank algae.1756

Algae, amazingly produces way more oxygen, I could say food, than all the trees combined on earth.1764

That is a mind trick to think about because there are so many billions of trees,1779

so many trees doing photosynthesis and cranking out oxygen in the atmosphere.1784

But if you were to add up all the algae in the oceans, in the lakes, in the rivers, in the ponds, etc,1788

they have more biomass amazingly.1794

Algae have more biomass than the trees, amazing.1798

When we take a breath, you thank algae, you can thank trees too.1806

Food, we actually use a lot of them for food.1810

One example I gave you earlier was seaweed that is used, it is technically a red algae that is used in sushi.1814

There are a lot of other examples of protists that are used to help us make food, as an ingredient in food.1822

Wastewater treatment, you can actually get protists to help you to filter out bad stuff out of the water.1830

Since taking advantage of the natural process that they can do, to help us clean our sewage.1839

Bacterial control, if you want to get rid a lot of bacteria in some fluid, 1846

introduce some protists that eat bacteria and then the bacteria is gone.1853

Ideally, you want to get to protists out eventually too.1858

You can use protists ability to eat bacteria to our advantage.1860

Filtration, that is this right here.1866

This is an assortment of diatoms.1871

I mentioned diatoms earlier on in the lesson.1876

They are used to make what is called diatomacious earth.1880

You get these out of the ocean, specifically the ocean floor.1892

It is all these little diatoms that have died and left over these amazing geometric shapes called tests.1896

Diatoms have tests made of silica or calcium carbonate.1903

You can see this awesome geometry that they all have, it is amazing the shapes that they form.1908

Or you can use this diatomacious earth, made of their little carcasses, to filter pool water.1912

I remember how my dad cleans out the pool filter when I was really young.1918

He would pour this like heavy bag and it looks like gray powder.1921

It is these, they are microscopic but it is billions and billions of these that can help filter pool water.1927

You are taking advantage of their little geometric structures to do that.1933

The bad side of protists is the disease that they can cause in us.1938

One example is this, it is called giardia.1942

It causes severe diarrhea among other problems.1950

If this gets in your intestines, no good, it is not a very good thing. You want to stay diarrhea free.1955

Thank you for watching