Domain Eukarya:Protista

Domain Eukarya

Every living thing on Earth, except for bacteria and archaea

More complex organization

Have a nucleus

Have membrane-bound organelles

Mitochondria, endoplasmic reticulum, Golgi bodies, etc.

4 kingdoms

Animalia

Plantae

Fungi

Protista

Kingdom Protista

The protists

Depending on who you ask ~10-20 phyla of protists exist

Single-celled and multicellular organism

Can be:

plant-like,

animal-like, or

fungi-like

Protista Reproduction

Can reproduce sexually and asexually

Many of the unicellular protists reproduce asexually (much like bacteria)

Have a method for exchanging genetic material (called conjugation)

They attach and exchange small pieces of DNA

Most protists reproduce sexually

Classification and Evolution of Protists “Trash-can” kingdom

If it is not a plant, animal, or fungus, it is a protest

Very hard to classify because there is such a diversity

Will likely be broken into several new kingdoms in the future

Scientists usually break them down into animal-like, plant-like, and fungi-like based on their traits

Were the first eukaryotes to evolve

Because they are small, they have not left a lot of fossils (only a few types have been found)

Comparing genetic evidence, they likely evolved early from single-celled organisms (prokaryotes) who had acquired structures that worked similar to organelles

Example: Prokaryotes “eat” by engulfing particles and bringing them into their membrane.

Endosymbiotic Theory

Endo=Inside (Think “enter”)

Symbiosis=2 organisms of different species working together

Endosymbiotic Theory=Organelles were once separate, but were “eaten” and formed mutualistic relationships

Eventually became parts of the cell

Helped organism to make energy (chloroplasts and mitochondria)

Evidence:

Mitochondria in eukaryotic organisms have different DNA from the organisms who have them (called Mitochondiral DNA)

This DNA shows more closely related genetic relationship to bacteria than to eukaryotes

Chloroplasts in eukaryotic organisms also have different DNA than the plants and protists that contain chloroplasts

This DNA can be traced directly to photosynthetic bacteria

Plant-Like Protists

Called algae

Algae are not plants! They are protists.

Contain chloroplasts

Producers-able to make their own food

Many also have cell walls, similar to plants

Many types of algae exist

Classified on whether they are unicellular or multicellular

Unicellular: Diatoms, Dinoflagellates, euglenoids

Diatoms

Small, unicellular algae.

Exist in large populations

Form beautiful structures as colonies (picture)

Cell wall is made of silica (pretty much glass)

https://www.youtube.com/watch?v=JYB5529hDPI

Dinoflagellates

Have 2 flagella

They spin as they move

Bioluminescence

https://www.youtube.com/watch?v=uqJbUKEPgXc

Euglenoids

Have characteristics of both plants and animals.

Many have chloroplasts, some do not

Some have the ability to make their own food when there is light, and must eat other organisms when there is no light

Found in most aquatic environments

You would find them in Fulda Lake

Have a photosensitive “eyespot” that helps them move toward light

No cell wall

Can use their cell membrane as a way to move

Also have flagella that helps propel them in liquid

https://www.youtube.com/watch?v=fI7nEWUjk3A

Red Algae

Multicellular

Sometimes called “seaweed”

Have chlorophyll for photosynthesis

They are red due to a red pigment

Live deeper than brown and green algae

Up to 200 m deep

Green Algae Multicellular or unicellular

“Seaweed”

Large amounts of chlorophyll

Most plant-like of all algae

Thought to be the ancestor of all plants

Most live in the water, but some live outside the water

Brown Algae

Multicellular

Called “Kelp”

Located between areas where green and red algae grow

Usually in cooler, salty water

Typically grow in “forests”-dense areas

Contain chlorophyll and a brown pigment

They are an important food source, for fish and humans

Can grow up to 100m (328 feet) long

Algae Benefits and Issues

Algae is an important producer in aquatic food webs

Especially diatoms and dinoflagellates

Algal blooms

Can bloom out of control and be toxic for other organisms (even humans)

Usually the result of dinoflagellates

Product uses

Carrageenan (from certain algae) is used in toothpaste, salad dressing, and pudding to give it a creamy texture

Ice cream and marshmallows use algin from brown algae to make them thick

Algin

Diatoms are used (because of their glass-like cell walls) in insulation and road paint (the stuff that shines at night)

Animal-like Protists

Also known as protozoans

Live in or on dead organisms that are found in water

Usually classified based on how they move

Ciliates

Protozoans that have cilia (hair-like structures on outside of cell) that help them swim

Flagellates

Have flagella that help them move

Pseudopods (“false feet”)

Part of the cell extends and pulls them along

Others

Some cannot move and must instead get nutrients from other organisms

Parasites

Importance of Protozoans

Food source for organisms

Help build up sediment

Symbiotic relationships

Termites have protozoans in their gut that help them break down wood

Dark Side of Protozoans

Some protozoans can cause disease

Typically, they have a very complicated life cycle

Often have an intermediate host that they must infect before getting to humans

Plasmodium malariae

Protozoans of the genus Plasmodium cause malaria

Begins when a person is bitten by a mosquito carrying undeveloped Plasmodium protozoans

In the human, they develop and begin reproducing in red blood cells

When the offspring grow, they cause the RBC to burst, releasing them to reproduce in other RBCs

Another mosquito bites the human and picks up red blood cells containing the offspring

They then bite another human, transmitting the disease

The cycle repeats

Symptoms of malaria

Vomiting, fever, tiredness, severe headache

Prognosis

With treatment, recovery is possible

However, it can kill hours after infection, before treatment is possible

In 2013, there were nearly 200 million people infected with malaria

584,000 died

https://www.youtube.com/watch?v=qvlTOhCmxvY

African Trypanosomiasis (African sleeping sickness)

Protozoan: Trypanosoma bruceli

Intermediate Host: Tsetse fly

Primary Host: Humans

Symptoms: Itching and headaches at first. Months later, heart and kidney dysfunction, brain infection, disrupted sleep patterns, and brain damage. Fatal if not treated.

Toxoplasmosis

Protozoan: Toxoplasmosis gondii

Intermediate Host: Mice, birds

Primary Host: Cats

Unintended Host: Humans

Symptoms: Most show no symptoms. However, brain inflammation and changes in behavior result.

In mice, the protozoan results in the mouse becoming attracted to cat urine

This results in the mouse being eaten by the cat

Humans become affected by cleaning cat’s litter boxes

Can be fatal in humans, but not commonly

Pregnant women risk passing it on to the fetus, and the fetus can become seriously infected.

“Crazy cat lady syndrome”

Fungus-Like Protists

Protists that were once considered to be fungi

Produce spores, similar to fungi, for reproduction

All are consumers

Most can move using pseudopods

Slime Molds “Dog vomit mold” or “scrambled egg mold”

Protists that form delicate, web-like structures on their food source

Mostly found on decaying logs or wood

Can feed on any dead or decaying organism

Decomposers or consumers

Sometimes both

Water Molds and Downy Mildews

Grow like mold on plants and animals

Some are parasitic

Water molds can kill fish

Downy mildew can kill plants

Most are decomposers

Have cell walls closely resembling plants

Produce spores like fungi

Can have negative economic effects

Water mold can spread quickly and kill a lot of fish

Downy mildew has, in the past, nearly wiped out crops

Also caused the Irish Potato Famine

Killed over 1 million people through starvation