Biology 106 Dr. Dudash

Study Questions Fall 1999

Study Questions Set #8 - Handed out 8 November 1999.

Due: In Lab the following week.

All answers MUST be TYPED unless mathematical computation is needed.

Use no more than one of a page of single spaced typed text.

Please answer 3 of the following questions:

1. How are bacteria classified?

1. More than 5000 known species

2. Most not based on evolutionary relationships

a. diversified too long ago

b. genealogy difficult to outline

c. potential for unrelated genera to exchange genes via transformation and transduction.

d. microfossils not easy to examine

3. Comparisons of ribosomal RNA have led to divisions into 20 major groups

STUDENTS MAY INCLUDE SOME OF THE FOLLOWING.

Two major groups which diverged very early in the history of life

a. Archea (formerly known as Archeabacteria)

- distinct from others

- RNA polymerase and ribosomal proteins are Eukaryote like

- cell walls lack muramic acid

- oldest life forms, tackle extreme environments

ex.'s, Methanogens = thrive where methan e produced, marsh grass and in the stomachs of rudiments.

Extreme halophiles = thrive in Great Salt Lake

Extreme thermophiles = thrive in 60-80 degree Celsius in hot sulfur springs.

b. Bacteria (formerly known as Eubacteria)

i. Gram negative rods, heterotrophs, important pathogens, ex. ii. Cyanobacteria, Chlorophyll A, carotenoids, phycobilin pigments, fix N, produce stromatolites, origin of chloroplasts of red algae

iii. Chloroxybacteria , single genus, contain chlorophyll B, postulated source of chloroplasts in green algae and plants

iv. Actinomycetes - gram positive, filamentous growth form, nitrogen fixers, many antibiotics (streptomyocin like),

2. Discuss the 3 methods of genetic recombination available to Prokaryotes.

a. Transformation = genes are taken up from the surrounding environment

b. Conjugation = genes are transferred directly from one bacterium to another bacterium

c. Transduction = genes are transferred between bacteria via viruses

ALL GENE TRANSFER ONE WAY!! and involve variable amounts of DNA

3. Discuss two examples of the metabolic diversity expressed by Prokaryotes

1. Photoautotrophs = harness light energy to synthesize organic comps from CO2

ex.'s, cyanobacteria, algae, plants

2. Photoheterotrophs = use light to generate ATP, but obtain carbon in organic form (not synthesized) ex., restricted to Prokaryotes

3. Chemoautotrophs = need CO2 as a carbon source, but obtain energy by oxidizing inorganic substances such as H2S, NH3, FE ++ or some other chemical

ex., unique to Prokaryotes

4. Chemoheterotrophs = must consume organic molecules for both energy and carbon

ex. Prokaryotes, protists, fungi, animals and MOST bacteria are in this group

5. Another category used to divide Prokaryote Metabolism is the Effect of Oxygen on the Organism

a. Obligate Aerobes = use O2 for respiration and cannot grow w/o it

b. Facultative Aerobes = use O2 if present, but can also grow by fermentation

c. Obligate Anaerobes = poisoned by O2

AND OTHERS - please see my lecture notes AND ABOVE.

4. What are the 3 most important events that occurred in the evolution of Protists?

1. Origin of eukaryotic cell

- flagella not homologous between Eukaryote & Prokaryote.

- Prok. flagella/ attached to cell surface.

- Euk. flagella and cilia are extensions of the cytoplasm with bundles of microtubules (9 +2 arrangement) covered by a plasma membrane).

2. Evolution of multicellularity

3. Sexual reproduction

5. Compare and contrast Gametic Meiosis and Zygotic Meiosis.

1. Zygotic Meiosis

- zygote only diploid stage of life cycle

- all other stages of life cycle haploid

ex., Chlamydomonous

 

2. Gametic Meiosis

- gametes are only haploid stage of life cycle

- all other stages are diploid

ex., animals