CHAPTER 20: Protists

High School Biology Class

Kingdom Protista

• Sometimes called “The Catchall Kingdom” because the organisms in it are those that have eukaryotic cells, but are NOT fungi, plants, or animals.

• Usually protists are identified by what they are NOT (i.e. bacteria, fungi, plant, or animal) rather than what they actually are.

What is a Protist?

• Protists - are members of the Kingdom Protista, a large and extremely varied group.

• There are currently over 115,000 species (very diverse) of protists that have been classified.

What is a Protist?

• The only trait that all protists have in common is that they all have a nucleus (eukaryotic cells).

• Protists are the hardest kingdom of organisms to classify because they do NOT share many traits.

Protist Examples

Protist Facts

• The word protist is from from the Greek word protistos, which mean “first.”

• Knowing this makes it easier to remember that protists were the “first eukaryotes” to evolve.– Fossils indicate that Protists arose about 1.5 mya.

Protist Facts

• Scientists hypothesize that protists evolved from bacteria that had formed symbiotic relationships. (Theory of Endosymbiosis)

Protist Types

• Scientists also hypothesize that protists diverged to create the Fungi, Plant and Animal Kingdoms.

• Therefore, there are three types of Protists:

1) Fungi-like Protists2) Plant-like Protists3) Animal-like Protists

Plant-like

Fungi-likePROTISTS

Animal-like

Characteristics of Protists:

• Some photosynthetic (like plants)• Some ingest food (like animals)• Some absorb food (like fungi)• All are Eukaryotic • Some with cell walls (some without) • Unicellular OR Multicellular • Autotrophic OR Heterotrophic

Flagella CiliaSexual Reproduction

* Sexual reproduction* Multicellularity* Mitosis and Meiosis* Complex flagella and cilia

They Were the 1st Kingdom to Exhibit:

Other Names Include:

• Protozoa = Heterotrophic protists

• Algae = Autotrophic (Photosynthetic) protists

Protozoa Algae

Reproduction:

• Usually protists reproduce ASEXUALLY in one of the following manners:

- Mitosis (like in fungi/animal/plant cells)

- Binary Fission(like in bacteria)

                                                                                                                                    

                            

Reproduction Continued:

• Sometimes protists reproduce SEXUALLY:* Sexually in “Unicellular Protists”

- During unfavorable conditions (lack of food and other resources) pairs of gametes fuse together into a zygote with a thick protective wall (zygospore).

Reproduction Continued:

• Sometimes protists reproduce SEXUALLY:* Sexually in “Multicellular Protists”

- Alternation of Generations = having both diploid and haploid phases.

Reproduction Continued:

• Sometimes protists reproduce SEXUALLY:* Sexually in “Multicellular Protists”

- Conjugation = a union of two protists to exchange genetic material.

Type of Animal-like Protists:

1. Sarcodines (Rhizopoda)

Example: Amoebas• Pseudopodia (false feet) - cytoplasmic extensions for

movement and feeding.

Amoebas proteus

Facts:

- Parasites

- Disease = Entamoeba histoltica

- Binary Fission

Type of Plant-like Protists:

2. Diatoms (Bacilliarophyta)– Photosynthetic, unicellular protists with unique double shells (made of silica) that looks like glass.

Diatoms

Facts:

- Reproduce asexually

- Found in oceans and lakes

3. Algae – Phototrophs– Green Algae (Chlorophyta) – have the same

pigments (chlorophyll A & B) as in plants.

– Produce 30-50% of the Earth’s Oxygen

Type of Plant-like Protists:

Green Algae

3. Algae - Phototrophs– Red Algae (Rhodophyta) - multicellular organisms

found in warm ocean waters.

– May live near in water or on land.

Type of Plant-like Protists:

Red Algae

3. Algae - Phototrophs– Brown Algae (Phaeophyta) - multicellular and found mostly in

cool marine type environments.

Example: Kelp

• The largest organism on Earth.

Type of Plant-like Protists:

KelpBrown Algae

Type of Plant-like Protists:3. Algae - Phototrophs

– Golden Algae (Chrysophyta) – unicellular or multicellular organisms that show a great deal of diversity as both autotrophs and heterotrophs.

Golden Algae

Type of Plant-like Protists:

4. Dinoflagellates (Dinoflagellata) – Unicellular, phototrophs with 2 flagella that are used for movement.

Dinoflagella

Facts:

- Parasites

- Disease = Red Tide

- Binary Fission

Red Tide

• Red Tide is the term used to describe the rapid reproduction of plankton (dinoflagellates). Red Tide affects soft-shell clams, mussels, oysters, and scallops.

• Symptoms include tingling in fingers, lips, and tongue as well as

headaches, dizziness, nausea, muscular paralysis and respiratory paralysis.

5. Zoomastigotes (Zoomastigina) – Unicellular, heterotrophs with one flagella.

Example: Trypanosomes• Protists that can cause African Sleeping Sickness.

Type of Animal-like Protists:

Trypanosomes

Facts:

- Parasites or symbionts

- Disease = Trypanosoma gambiense

- Binary Fission or Meiosis

- Termites need them to live (digest cellulose)

African Sleeping Sickness

• African Sleeping Sickness is caused by the tsetse flies which bites a person or animal and injects the trypanosome protist into the victim.

• Among the first symptoms and signs of African sleeping sickness are headaches, irregular fevers, swollen tissues and joint pains.

• At a later stage the parasites invade the brain, which usually leads to mental disorders, coma and eventually death.

6. Euglenoids (Euglenophyta) – Freshwater, unicellular protists with two flagella.

Example: Euglena

a) Pellicide - protein layer inside cell membrane.

b) Eyespot – (photoreceptor) moves toward light.

Type of Plant-like Protists:

7. Ciliates (Ciliophora)– Cilia - short flagella (hairs) used for movement.

– Unicellular heterotrophs with two nuclei.

Example: Paramecium

• Reproduce by mitosis or conjugation.

Type of Animal-like Protists:

Paramecium

Facts:

- Macronucleus = cell growth

- Micronucleus = cell reproduction

- Contractile Vacuole – pumps water out

8. Cellular Slime Molds (Acrasiomycota)– Resemble amoebas, but during environmental stress,

they form colonies that reproduce by spores.

Type of Fungi-like Protists:

Fuligo septica

9. Plasmodial Slime Molds (Myxomycota)– Plasmodium - mass of cytoplasm that looks like oozing slime (contain 1,000 nuclei).

Type of Fungi-like Protists:

Physarum

10. Water Molds (Oomycota)– Parasites with two flagella (1 in front and 1 in back).

Saproglenia

Type of Fungi-like Protists:

11. Sporozoans (Sporozoa)– Parasitic protists that form spores during reproduction.

– Cause malaria and toxoplasmosis.

Type of Animal-like Protists:

Facts:

- Parasites

- Disease = Plasmodium species

- Disease = Toxoplasmosis gondii

- Nonmotile Complicated Life Cycle

Malaria

• Malaria is caused by the mosquito which bites a person or animal and injects the plasmodium protist into the victim.

• Malaria can cause a variety of symptoms including general malaise, fever, vomiting, pain, anemia, and convulsions.

• If left untreated, some infected individuals can lapse into a coma, and severe anemia is often a cause of death.

Protist Diseases:

~ Protists cause diseases in humans and animals -

(Page 490 Table 22-3)

Protists Are Beneficial As Well:

1) Human and Animal Digestion

Example: Cattle can digest hay and grass because various protists can help them break it down into simpler substances.

2) Plankton in Oceans Support Food Chains

Example: Plankton/Algae are the largest group of organisms that can perform photosynthesis and thus make food for others.

Protists Are Beneficial As Well:

3) Photosynthesize and Produce Oxygen

Example: Algae are the largest group of organisms that can perform photosynthesis and thus make oxygen for others.

Protists Are Beneficial As Well:

ALGAE

4) Recycle Nitrogen, Carbon and Phosphorus

Protists Are Beneficial As Well:

Nitrogen Cycle Carbon Cycle Phosphorus Cycle

Protist Fun:

Any Questions?

• “Information is the currency of democracy.”--Ralph Nader

• “There is an old saying that the course of civilization is a race between catastrophe and education. In a democracy such as ours, we must make sure that education wins the race.”

--JFK