Archaea

Definition

Archaea are a domain of single-celled microorganisms that are genetically distinct from bacteria and eukaryotes. They often inhabit extreme environments but can also be found in more common habitats.

5 Must Know Facts For Your Next Test

1. Archaea have unique lipid membranes that differ significantly from those of bacteria and eukaryotes, providing resilience in extreme conditions.
2. They possess genes and metabolic pathways that are distinct from both bacteria and eukarya, often leading to unique biochemical capabilities.
3. Many archaea thrive in extreme environments such as high temperatures, high salinity, or acidic conditions, known as extremophiles.
4. Unlike bacteria, archaea do not contain peptidoglycan in their cell walls; instead, they have pseudopeptidoglycan or other polymers.
5. Archaeal RNA polymerases are more similar to eukaryotic RNA polymerases than to bacterial ones, indicating a closer evolutionary relationship with eukaryotes.

Review Questions

• What makes archaeal lipid membranes unique compared to those of bacteria and eukaryotes?
• In what types of environments are archaea most commonly found?
• How do the RNA polymerases of archaea compare to those of bacteria and eukaryotes?

Related terms

Extremophiles: Microorganisms that thrive in extreme environmental conditions such as high temperature, salinity, or acidity.

Pseudopeptidoglycan: A polymer found in the cell walls of some archaea that is similar but not identical to the peptidoglycan found in bacterial cell walls.

RNA Polymerase: An enzyme that synthesizes RNA from a DNA template during transcription.