Lecture 2: Microbial Diversity

Question 1

Diversification of life

Question 2

Diversification of life

Answer 2

• bacteria diverged before Archaea diverged from Eukaryotes
• Fundamental properties found in cells evolved from the common ancestor
  > the cell membrane
  > DNA, RNA, & protein roles (including synthesis, transcription, & translation mechanisms)

Many differences between each domain, some interesting similarities

Question 3

Similarities between Bacteria & Archaea

Answer 3

Characteristic:Bacteria&Archaea| Eukaryotes

1. Cell volume: 1-100 µm3 | 1-106 µm3
2. DNA Chromosome: Usually circular | Linear
3. DNA Organisation: Nucleoid | Membrane-bound nucleus
4. Gene Organisation: Multigene operons | Single genes
5. Metabolism: Varied (dentrification, N2 fixation, lithotrophy, respiration, fermentation) | Respiration & fermentation
6. Multicellularity: Single/simple | Single & complex

Question 4

Similarities between Archaea & Eukaryotes

Answer 4

Characteristic:Archaea&Eukaryotes| Bacteria

1. Intron splicing: Introns common | Introns rare
2. RNA polymerase: Similar (orthologous) | Bacterial- specific
3. Transcription factors: Similar (orthologous) | Bacterial specific
4. Ribosome sensitivity (chloramphenicol, kanamycin, streptomycin): Insensitive| Sensitive
5. Translation initiator: Methionine (expect in mitochondria - formylethionine)| Formylmethionine
6. Cell wall: Variable (Pseudopeptidoglycan, cellulose, chitin, glucans, proteins) | Peptidoglycan

Question 5

Similarities between Bacteria & Eukaryotes

Answer 5

Characteristic:Bacteria&Eukaryotes| Archaea

1. Methanogenesis: No | Yes
2. Thermophilic growth: Up to 80/90˚C | Up to 120 ˚C
3. Photosynthesis: Yes* | Haloarchaea only (bacteriorhodospin)
4. Light absorption: Red & blue | Green
5. Major membrane lipids: Ester-linked fatty acids | Ether-linked isoprenoid
6. Pathogenic lifestyle: Many pathogens | No pathogens