CHAPTER 20: Protists High School Biology Class
Jan 06, 2018
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