Lectures: Bacteria vs Archaea

Question 1

What are the 4 LUCA traits (Last Universal Common Ancestor)?

Answer 1

1. LUCA traits:
   - Cells
   - Central Dogma
   (DNA –> RNA –> proteins)
   (Genetic code)
   - Adenosine Triphosphate (ATP)
   - Organic compounds with
   carbon-hydrogen bonds

Question 2

What are the 3 shared traits of Bacteria?

Answer 2

2: shared traits of Bacteria:
- Peptidoglycan in cell walls
- Short RNA polymerases
- Translation starts with N-formylmethionine

Question 3

What are the 3 shared traits of Archaea+Eukarya?

Answer 3

3: shared traits of Archaea+Eukarya:
- Long RNA polymerases
- Translation starts with methionine
- Histone proteins

Question 4

What are the 2 types of diversity within Bacteria?

Answer 4

1. Gacilicutes:
   - Mostly Gram-negative
   - Includes: Proteobacteria, Bacteroidota
2. Terrabacteria:
   - Mostly Gram-positive
   - Includes: Firmicutes, Actinobacteria, Cyanobacteria

Question 5

Gracilicutes: Proteobacteria:

Answer 5

• Most diverse group of bacteria
• Taxonomic: at least 5 classes, many genera
• Shapes: cocci, bacilli, spirilli
• Metabolic: includes all 4 categories of metabolism
• Ecological: variety of roles in ecosystem, including
  species that…
  a) fix nitrogen
  b) extract metals (using in mining, causes radioactive waste)
  c) are human pathogens (e.g., Escherichia, Salmonella)

Question 6

Gracilicutes: Bacteroidota:

Answer 6

• Found in a wide variety of habitats and fill many ecological niches
• Important members of the human gastrointestinal microbiome:
  a) aid in degrading complex polysaccharides, protein
  metabolism, deconjugation of bile acids, and other roles
  b) disruption of Bacteroidota communities associated with
  digestion illnesses

Question 7

Terrabacteria: Firmicutes:

Answer 7

• Found in a various environments
• Many produce endospores
• Important members of the human
  gastrointestinal microbiome (associated with obesity)

Question 8

Endospores

Answer 8

tough dormant versions (compartments) resistant to desiccation (drying)

Question 9

Terrabacteria: Actinobacteria:

Answer 9

• Variety of roles, but best known for important contributions to soil environment
• Decomposition of organic matter
• Some live symbiotically with plants and provide nitrogen (nitrogen fixation) and receive saccharides

Question 10

Terrabacteria: Cyanobacteria

Answer 10

aka blue-green algae
- Obtain energy via photosynthesis
- Evolved ~ 2.6 bya and had oxygenic
photosynthesis metabolism (created oxygen as byproduct)
- Led to “oxygenation” of atmosphere ~2.3-2.1 bya
- Allowed evolution of more efficient aerobic metabolism

Question 11

What traits differ Gracilicutes & Terrabacteria?

Answer 11

4: Gracilicutes
(mostly) Gram-negative

5: Terrabacteria
(mostly) Gram-positive

Question 12

True or False? Archaea is not monophyletic.

Answer 12

True

Question 13

Archaea: DPANN:

Answer 13

• Small in size compared to other Archaea
• Obligate symbionts with reduced genomes
• Its everywhere but poorly understood

Question 14

Archaea: Euryarchaeota:

Answer 14

• Variety of ecological roles
• Includes methanogens (produce
  methane during metabolism)
• Others degrade hydrocarbons,
  degrade organic matter, or
  involved in marine carbon cycle
• Many found in “extreme”
  environments, but some can be
  found in moderate environments

Question 15

Archaea: TACK:

Answer 15

• Variety of roles
• Can be numerically abundant, particularly in oceans

Question 16

Archaea: Asgard:

Answer 16

• First described from so-called Loki’s Castle hydrothermal vent site in Arctic Ocean
• Genetically most closely related to Eukarya