Kingdom Protista

Kingdom Characteristics• Eukaryotic• Mostly unicellular (microscopic)

some are multicellular

• Autotrophic, Heterotrophic, and both• Most reproduce asexually, but some can use

conjugation (exchange of genetic material)• Cell wall may or may not be present• Taxonomic Misfits–

Contains all eukaryotic cells that can’t be classified as plant, animal or fungus

Evolutionary ImportanceProtists are considered to be the ancestors of

the three multicellular kingdoms—fungi, plant, animal

Major Divisions of ProtistsPlant-like Protists (Algae)Animal-like Protists (Protozoans)Fungus-like Protists (Slime Molds)

Plant-like Protists—AlgaeAutotrophicContain cell wallsMost are immobile—some are mobile

Examples of Plant-like Protists:Green, Red, and BrownAlgaeCellular Organization:

– Multicellular (Red and Brown) Green algae can be either

• Nutrition: Photosynthetic (Autotrophic)

Locomotion: Non-motile

Habitat: Red Algae: Marine Green Algae: Fresh, Marine, Soil Brown Algae: Marine

Classified by their pigment Green, Red, or Brown (kelp) Algae

Used in many foods such as pudding, jelly, jelly beans, ice cream, marshmallows, salad dressing

Diatoms• Cellular Organization:

– Unicellular• Nutrition:

– Autotrophic• Locomotion:

- Non-motile• Habitat:

– Fresh and Marine• Shells made out of silica (glass-like)

Euglenoids• Cellular Organization:

– Unicellular• Nutrition:

– Heterotrophic/Autotrophic• Locomotion:

- 1 or 2 Flagella• Habitat:

– Aquatic• Ex: Euglena

Animal-like Protists– a.k.a. Protozoans• Heterotrophic• All are unicellular• None contain cell walls• Most can move:– Cilia- hair-like projections– Flagella- whip-like tail– Pseudopod- “false foot”

Sarcodines- Ameoba• No cell wall gives them flexibility• Cellular Organization:

– Unicellular• Nutrition:

– Heterotrophic• Locomotion:

-Pseudopods• Habitat:

– Fresh and salt water• Some may cause disease (they are parasites)

Flagellates• Cellular Organization:

– Unicellular• Nutrition:

– Heterotrophic• Locomotion:

-flagella• Habitat:

-free living and parasitic• Ex: Trypanosomes causes AfricanSleeping

Sickness

Ciliates• Cellular Organization:

– Unicellular• Nutrition:

– Heterotrophic• Locomotion:

- cilia• Habitat:

- fresh water and marine• Ex: Paramecium, Vorticella and stentor

Sporozoans• Cellular Organization:

– Unicellular• Nutrition:

– Heterotrophic• Locomotion:

-Non-motile• Habitat:

-parasitic• Ex:– Plasmodium-Malaria

Fungus-like Protists- slime molds• Heterotrophic

decomposers• Contain cell walls• Multicellular• Exist in different

forms and produce spores

• Reproduce by forming spores

• 3 types:water molds, downy mildews, and slime molds

Slime Molds• Cellular Organization:

– Multicellular• Nutrition:

– Heterotrophic• Locomotion:

- amoeboid movement• Habitat:

- cool, moist, shady places

Watery/Downy Molds• Cellular Organization:

– Multicellular• Nutrition:

– Heterotrophic (either parasites or feed on dead organic matter)

• Locomotion: - amoeboid movement

• Habitat: -cool, moist, shady places

• Cause of the Irish potato famine in 1845-1850 that killed 1 million people

Ecological Importance of Protists

• Autotrophic protists are primary component of PHYTOPLANKTON

• They carry out 70 – 80% of the world’s photosynthesis

• They are the base of most of the world’s food chains

Negative Contributions of Protists

• Many cause disease– Malaria, sleeping sickness, amebic dysentery, etc.

• Responsible for “Red Tide” that poisons shell fish

• Algae blooms result in fish kills

Paramecian Fission (asexual)

Paramecium Conjugation Two individuals line up with each other and make

contact with their oral groove, The micronucleus (2N) undergoes meiosis result-

ing in four micronuclei in each of the two cells (N) 3 micronuclei degenerate and are digested by the

cell. The remaining micronucleus in each paramecium

divides once again, by mitosis. By the time this has occurred, most of the cell

membrane dividing the two cells is gone. The two halves (originally two cells) then exchange

one of their micronuclei. The cell membrane between the two halves gets

rebuilt and the two cells separate again. The two haploid micronuclei (one original and one

new) fuse into a single diploid micronucleus. The original macronucleus, disintegrates and gets

digested by the cell’s enzymes. The micronucleus divides by mitosis to produce

two identical diploid micronuclei in each individual.

One of the micronuclei then becomes the real micronucleus while the other one grows and becomes the new Macronucleus.

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