Topic 3: Archaea Flashcards

1
Q

Carl Woese

A
  • Carl Woese was the first to identify and demonstrate how the Archaea form their own distinct branch in the tree of life
  • Carl Woese and George Fox 1970s
  • Discovered by sequencing RNA
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2
Q

Archaea and Bacteria Common Features (6)

A
  1. Size and shapes
  2. Shared biomarkers
  3. Inclusion bodies
  4. Circular chromosome (for most)
  5. Nucleoid region
  6. Cytoskeleton (for some)
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3
Q

Archaea and Eukaryotes Common Features (3)

A
  1. One of their polymerases
  2. Histone proteins
    —-Both eukaryotes and archaea have histone proteins, but eukaryotes have a slightly different arrangement of DNA around the histone proteins.
  3. Cytoskeleton (for some)
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4
Q

Methanogens

A
  • Methane producing organisms
  • Euryarchaeota contains all known methanogens
  • Live in oxygen-poor environments (e.g., digestive tracts, cecum, rumen, hydrothermal vents, waste water sludge, termite guts)
  • Energy Sources:
    —Hydrogenoclastic methanogens use hydrogen as an energy source. There are the most common group of methanogens in the environment
    — Acetoclastic use acetate
    — Methylotrophic use methanol
    -Volta Experiment shows how much energy is present in the form of heat and light.
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5
Q

Extremophiles

A
  • Halophiles (high salt)
  • Thermophiles (temp over 55C)
  • Hyperthermophiles (temp over 80C)
  • Acidophiles (acidic environment)
  • Barophiles (high pressure)
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6
Q

Phyla of the Archaea

A

T
- Thaumarchaeota
–Most abundant organisms on Earth
N
- Nanoarchaeota
–Only one member
E
- Euryarchaeota
–Methanogens
C
- Crenarchaeota
–Extremophiles
K
- Korarchaeota
– Newly recognized phylum

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7
Q

Thaumarchaeota

A
  • Low-temperature archaea extremely important for the cycling of nutrients (e.g., carbon and nitrogen) and production of vitamins in the ocean
  • In ocean, outnumber bacteria, especially at greater depths
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8
Q

Halophiles

A
  • Euryarchaeota
  • salt loving
    found in ponds where water evaporates
  • Survive high-salt (sodium) conditions by concentrating another salt, potassium, within their cells
    — Has more guanine and cytosine content in its genome to stabilize DNA in presence of so much potassium
  • Red colour comes from retinal, which captures light energy
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9
Q

Nanoarchaeum

A
  • One member: Nanoarchaeum equitans
    – Possibly smallest microorganism
    – Discovered in hydrothermal vent north of Iceland
    – Associates with Ignicoccus hospitalis
    Possible parasite:
    — No metabolic genes
    — Can’t make ATP
    — Can’t make amino acids
    — Can’t make nucleotides
    — Can’t make lipids for its membrane
    — DOES produce S-layer
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10
Q

Shapes of cells found within archaea

A

Rods, cocci, spirals (similar to bacteria)

Irregular shapes (Sulfolobus spp.)

Rectangular shapes (Thermoproteus spp.)

Squares (Haloquadratum walsbyi)

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11
Q

Explain how Halo bacterium tolerates high salinity

A
  • Halobacterium are halophiles (salt-loving) bacteria
  • They can tolerate high salinity because a very high intracellular [K+] offers a high extracellular [Na+]
  • The ions balance and there is no net gain or loss of water
  • high intracellular concentration of potassium (K+) can denature proteins and split DNA
  • Phototrophic
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12
Q

Explain where you would find methanogens and why

A
  • In the phylum Euryarchaeota
  • Produce methane
  • Strict anaerobes
    Found in:
  • Anoxic sediments (marshes/swamps, lakes, rice paddies, moist landfill)
  • Animal digestive tracts
  • Found in Low oxygen environments (Gut, swamps)
  • Geothermal H2/CO2 sources
  • Artificial biodegradation facilities
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13
Q

Describe why the relationship between Nanoarchaeum and Ignicoccus is “bizarre”

A
  • Parasitic nanoacheraeum acts as a s-layer or membrane to the host ignicoccus
  • It surrounds and covers the ignicoccus
  • Not confirmed symbotic relationship because cant make lots of things
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