CHAPTER 22: Protists

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CHAPTER 22 Protists

• High School Biology Class

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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.

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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.

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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.

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Protist Examples
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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.

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Protist Facts

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

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Protist Types

• Scientists also hypothesize that protists
  diverged to create the Fungi, Plant and Animal
  Kingdoms.
• Therefore, there are three types of Protists

• Fungi-like Protists
• Plant-like Protists
• Animal-like Protists

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Plant-like
Animal-like
Fungi-like
PROTISTS
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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

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They Were the 1st Kingdom to Exhibit
Sexual reproduction Multicellularity
Mitosis and Meiosis Complex flagella and cilia
Flagella
Cilia
Sexual Reproduction
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Other Names Include

• Protozoa Heterotrophic protists
• Algae Autotrophic (Photosynthetic) protists

Protozoa
Algae
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Reproduction

• Usually protists reproduce ASEXUALLY in one of
  the following manners
• - Mitosis
• (like in fungi/animal/plant cells)
• - Binary Fission
• (like in bacteria)

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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).

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Reproduction Continued

• Sometimes protists reproduce SEXUALLY
• Sexually in Multicellular Protists
• - Alternation of Generations having both
  diploid and haploid phases.

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Reproduction Continued

• Sometimes protists reproduce SEXUALLY
• Sexually in Multicellular Protists
• - Conjugation a union of two protists to
  exchange genetic material.

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Type of Animal-like Protists

• 1. Sarcodines (Rhizopoda)
• Example Amoebas
• Pseudopodia (false feet) - cytoplasmic extensions
  for movement and feeding.

• Facts
• Parasites
• Disease Entamoeba histoltica
• Binary Fission

Amoebas proteus
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Type of Plant-like Protists

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

• Facts
• Reproduce asexually
• Found in oceans and lakes

Diatoms
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Type of Plant-like Protists

• 3. Algae Phototrophs
• Green Algae (Chlorophyta) have the same
  pigments (chlorophyll A B) as in plants.
• Produce 30-50 of the Earths Oxygen

Green Algae
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Type of Plant-like Protists

• 3. Algae - Phototrophs
• Red Algae (Rhodophyta) - multicellular organisms
  found in warm ocean waters.
• May live near in water or on land.

Red Algae
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Type of Plant-like Protists

• 3. Algae - Phototrophs
• Brown Algae (Phaeophyta) - multicellular and
  found mostly in cool marine type environments.
• Example Kelp
• The largest organism on Earth.

Kelp
Brown Algae
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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
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Type of Plant-like Protists

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

• Facts
• Parasites
• Disease Red Tide
• Binary Fission

Dinoflagella
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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.

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Type of Animal-like Protists

• 5. Zoomastigotes (Zoomastigina)
• Unicellular, heterotrophs with one flagella.
• Example Trypanosomes
• Protists that can cause African Sleeping Sickness.

• Facts
• Parasites or symbionts
• Disease Trypanosoma gambiense
• Binary Fission or Meiosis
• Termites need them to live (digest cellulose)

Trypanosomes
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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.

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Type of Plant-like Protists

• 6. Euglenoids (Euglenophyta)
• Freshwater, unicellular protists with two
  flagella.
• Example Euglena
• a) Pellicide - protein layer inside cell
  membrane.
• b) Eyespot (photoreceptor) moves toward light.

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Type of Animal-like Protists

• 7. Ciliates (Ciliophora)
• Cilia - short flagella (hairs) used for movement.
• Unicellular heterotrophs with two nuclei.
• Example Paramecium
• Reproduce by mitosis or conjugation.

• Facts
• Macronucleus cell growth
• Micronucleus cell reproduction
• Contractile Vacuole pumps water out

Paramecium
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Type of Fungi-like Protists

• 8. Cellular Slime Molds (Acrasiomycota)
• Resemble amoebas, but during environmental
  stress, they form colonies that reproduce by
  spores.

Fuligo septica
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Type of Fungi-like Protists

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

Physarum
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Type of Fungi-like Protists

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

Saproglenia
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Type of Animal-like Protists

• 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
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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.

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Protist Diseases

• Protists cause diseases in humans and animals -
  
• (Page 490 Table 22-3)

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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.

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Protists Are Beneficial As Well

• 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.

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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.

ALGAE
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Protists Are Beneficial As Well

• 4) Recycle Nitrogen, Carbon and Phosphorus

Nitrogen Cycle
Carbon Cycle
Phosphorus Cycle
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Protist Fun
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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