Chapters 29-30: Protista

Protista

1) Eukaryotic
a) Greek for "true nucleus"(good kernel).
b) More than 10 micrometers in diameter
c) Elaborate shapes (branch, filamentous, tetrahedral, etc.)

2) Unicellular, multicellular, and colonial.

3) Sexuality evolved with this Kingdom.

4) Ancestors of plants, fungus, and animals.

Transition Between Prokaryotes and Eukaryotes:

Pelomyxa palustris: the only member of Phylum Caryoblastea

1) Single-celled ameboid protist, lives at the bottom of ponds.
2) Nucleus divides more like a prokaryote than a eukaryote.
3) No mitochondria; has bacteria living in it that serve a similar purpose.

Endosymbiotic Bacteria:

1) Live within other cells, perform specific functions for thir host.

2) Endosymbiotic Theory by Lynn Margulis of University of Mass. in the 1960's.
a) Theory states that a critical stage in evolution of the eukaryote cells involved endosymbiotic relationships with prokaryotic organisms (bacteria).
b)Energy-producing bacteria may have come to reside within larger bacteria, eventually evolving into mitochondria (powerhouse).
c) Photosynthetic bacteria may have come to live in association with other larger bacteria, leading to the evolution of chloroplasts- the photosynthetic organelles of plants and algae.
d) Bacteria with flagella may have become symbiotically involved with non-flagellated bacteria, producing larger, motile cells.

Photosynthetic Protists (Algae):

A) Phylum Chlorophyta:

1)Green Algae
-Once incorrectly believed to have given rise to land plants
-Cells of Chlorophyta contain organelles called chloroplasts in which photosynthesis occurs.
-Photosynthetic pigments are chlorophyll a and chlorophyll b and various carotenoids.
-They are the same as those found in plants and are found in similar proportions.

2) Most aquatic- found in fresh and salt water (but not all)

3) Unicellular, filamentous and colonial
-Those that are motile have two apical (tip) or sub-apical flagella.
-Terrestrial algae occurs on moist trunks of trees, moist soil, moist rocks (even on snow).
-Various species are highly specialized, some living exclusively on turtles, green sloths of Costa Rica, or within the gill mantles of marine mollusks.

4) Reproduction in green algae is asexual and sexual: Alternation of Generations
(How things reproduce is a big part of evolution)
a) First phase produces spores - sporophyte (2n, diploid)
b) Second phase produces gametes - gametophyte (1n, haploid)

Lab Examples: Chlamydomonas- has a red eye-spot; Volvox, forms colonies 500-60,000 organisms that act as one unit; Spirogyra and Cladophora- filamentous

B) Phylum Streptophyta (Chara)

Stoneworts (Brittleworts) with calcium carbonate/limestone secretions
(See Figure 30.1, page 582)

1) Precursor to land plants
2) 450 million years old
3) Ancient fossils same as today
4) They are encrusted with white lime
5) Grow several feet tall, slender, threadlike, with whorls of branches a few inches in length
6) Found in fresh water or mildly brackish water (in estuaries)
7) 3 things that make them unique:

a) Unlike most algae which consist of single cells, simple colonies, or chains, stoneworts grow upwards; branches come off of giant central cells.
- giant cells contain many nuclei, are several times the width of a human hair, and an inch or more in length.
b) They have a relatively advanced feature of sexual reproduction which uses eggs and sperm.
c) Their biochemical processes are more similar to land plants than other green algae.

C) Phylum Phaeophyta

1) Brown algae

2) Marine, largest of the algae; kelp. Found worldwide.
-Unique ability to withstand pounding tides due to holdfasts and mucilaginous cell walls.

3) Multicellular

4) Blade: (not a leaf) but leaf like; stipe: resembles a stem; holfasts: resemble roots.
5) Chlorophyll a and c; pigment fucoxanthin (may slow prostate cancer).
6) Reproduction by alternation of generations
7) Economically important: food, fertilizer, iodine, salts, alginic acids (used as an emulsifier in dripless paint, ice cream, pudding mixes, etc.). An emulsifier allows water and oil to mix.

Lab Examples: Fucus and Laminaria

D) Phylum Rhodophyta

1) Red algae
2) Marine, both shallow and deep
3) Multicellular
4) Chlorophyll a, phycoerythrin: red pigment
5) Reproduction by alternation of generations
6) Economically important: food crop, agar, carageenan (stabilizes paint, ice cream, etc.)

Example: Coralline: Have cellulose cell walls impregnated with calcium carbonate- contribute much to the growth of coral reefs

Lab Examples: Polysiphonia and Porphyra