Download - High School Biology Class

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).


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

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


• 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


Green Algae

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

found in warm ocean waters.

– May live near in water or on land.


Red Algae

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

cool marine type environments.

Example: Kelp

• The largest organism on Earth.


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


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.


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.


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

– Unicellular heterotrophs with two nuclei.

Example: Paramecium

• Reproduce by mitosis or conjugation.


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).


Physarum

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

Saproglenia


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

– Cause malaria and toxoplasmosis.


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.


3) Photosynthesize and Produce Oxygen

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


ALGAE

4) Recycle Nitrogen, Carbon and Phosphorus


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