Archaea

Question 1

Basic Information

Answer 1

• Single celled
• Large Domain: microorganism
• Among Earth’s first life forms
• Found in almost all habitats (even extreme ones)
• Was not considered separate from bacteria until 1977
• Originally thought to be rare and only found in extreme environments but they are found in almost all habitats
• Little is know about them because: they are difficult to grow in the lab, and they are difficult to get to their habitats (genetics is a way to find out more about them)

Question 2

Similarities: Archaea vs. Bacteria

Answer 2

Anatomy:
- Single-celled
- No nucleus or organelles
- DNA itself or in the form of single circular chromosome (+ plasmid)

Reproduction:
- Binary fission
- Horizontal gene transfer: transformation, transduction and conjunction

Can be autotrophs or heterotrophs

Question 3

Similarities: Archaea vs. Eukarya

Answer 3

DNA replication and organization, and protein synthesis

Question 4

Unique features of archaea

Answer 4

• Unique membrane lipids
• Can survive in extreme environments where other domains cannot

Question 5

Explain extremophiles

Answer 5

Can live in extreme conditions
1. Acidophiles: extreme acidic conditions (pH <3). e.g. ARMAN archaea - closest known relative to the common ancestor of all life
2. Halophiles: extreme salinity conditions (5% - 35%… ocean is 3.5%). e.g. Haloarchaea - autotropic, pink pigment
3. Thermophiles: extreme heat (<100 degrees C). e.g. Sulfulobus, autotrophic archaea that grow in hot volcanic springs

Question 6

Archaea and the production of methane

Answer 6

Methanogenesis: form of anaerobic respiration that produces methane as a byproduct, methanogens (archaea)
Aquatic environment:
- O2 runs out the deeper you go because aerobic organisms use it up… methanogens produce methane as a last step of decomposition
Carbon can either be stored at the bottom of the ocean or released into the atmosphere as methane (more is being released as the planet warms)
Digestive tracks:
- Methanogens produce methane in gut of animals as they break down what cannot be broken down by anything else (this produces methane released as burps/farts)
- Methane is a major greenhouse gas which is a leading cause of climate change (96% of mammals are livestock and humans)
- Solution: biogas generators