Archaea Flashcards
Chapter 1
What is Archaea?
Archaea is a domain of prokaryotic organisms that differ from bacteria in the cell wall and plasm membrane chemistry, 16s RNA sequences and environment thrive in extreme environments.
Phylum: Euryarchaeota
-Biggest archaea phylum
-includes halophilic and methanogenic forms
Ex: Pryococcus furiosus
Genera: Methanobacterium, Halobacterium
Why are Methanococcus and Methanobacterium unique among all life forms
They can generate methane form simple carbon compounds
-Strict anaerobes found in hot springs and marshes
Characteristics of Thermoplasmata and Thermococci
-Highly acidophilic and moderately thermophilic
-Completely lack a cell wall, and are pleomorphic (lacking a regular shape)
Phylum: Crenarchaeota
-Nearly all extreme thermophiles (>100°C)
-optimum temp 106°C
Ex: Pyrolobus fumarii
Genera: Thermoproteus, Sulfolobus
What are the key habitats of Archaea?
Archaea are found in hot springs, marshy areas, extreme salty areas, and also in human gut, skin, and mouth.
Describe the cell structure of Archaea.
Archaea are unicellular with no membrane-bound organelles, possess a single circular chromosome, and often have plasmids.
How do Archaea reproduce?
Archaea reproduce asexually through binary fission or multiple fission and exhibit horizontal gene transfer.
How are Archaea classified based on molecular phylogenetics?
Two main phyla:
-Euryarchaeota (e.g., methanogens, halobacteria)
-Crenarchaeota (e.g., Sulfolobus, Pyrobaculum).
What are the differences between Archaea and Bacteria?
Archaea lack peptidoglycan in their cell walls, have ether-linked lipids in membranes, and show molecular similarities to eukaryotes.
What is unique about the metabolism of Archaea?
Archaea exhibit diverse metabolism, including chemolithotrophy, methanogenesis, and energy derivation from sunlight without chlorophyll.
What are methanogens?
Methanogens are Archaea that produce methane in anaerobic conditions, found in marshy areas and the gut of ruminants.
What are thermoacidophiles?
Thermoacidophiles are Archaea that thrive in extreme temperatures and acidic environments, such as hot sulphur springs.
What are halophiles?
Halophiles are salt-loving Archaea that live in high-salinity environments like salt flats and maintain osmotic balance with high internal salt content.
What type of cell membrane do Archaea have?
Archaea have membranes with ether-linked lipids instead of ester-linked lipids found in bacteria and eukaryotes.
