Archaea Flashcards
Why was the discovery of asgard archaea achanging point in archaeal research
ASGARD were defined as the direct ancestors of eEukarya, changing the initial phylogenetic tree. First: tree had 3 branches (eukarya, bacteria and archaea) now there are 2, Bacteria and Archaea, and Eukarya is brachedd off of Archaea
What are similarties between bacteria and archaea
They are both prokaryotic, with single circular DNA and 70s ribosomes
What are differences between bacteria and archaea
their cell membranes consist of different fatty acid structures. Cell wall: archaea don’t have peptidoglycan and can have an S-layer
How are archaeal cell walls different to Bactiera?
Archaea have an S-layer formed by the same type of proteins assembled symmetrically. They do not have the bacterial peptidoglycan, outer membrane, or periplasm. They can have: a pseudomuerin or methanochondroitin cell wall structure, along with a periplasm-like pseudo periplasm structure
How are the archaea cell membranes different to bacteria?
CM consists of L-glycerol and ether linked isoprenes either in bi, mono or mixed form. In bacteria, the cell membrane is ALWAYS a bilayer of ester linked fatty acids
Why are the differences beneficial for archaea?
The tetra-ether monolayer and the S-layer are better in extreme environments with high temperatures, as the splitting of the cell membrane is less likely with a monolayer and the s-layer is a rigid protective layer.
What are euryarchaeota?
Clade of archaea that makes up halophiles (salt loving), thermophiles and methanogens. ANME are methanotrophs in a clade that is very closely related to methanogenic Euryarchaeota.
What are ANME?
anaerobic methanotrophic archaea. They do a reverse methanogenesis pathway to consume CH4.
Who can live in close consortium with ANMEs and why?
Sulfate reducers: to exchange electrons via direct interspecies electron tranfer
Nitrate dependent anaerobic methane oxidation found?
water locked nitrate rich environments: rice paddys, fields, ditches
How do rice fields release methane
most is consumed by aerobic and anaerobic methanotrophs within the sediment: rice plants have an airway through their roots into the environment to transport O2 into the roots.
The roots can also allow methane to escape the sediment
How are the roots of rice plants called?
Aerenchyma
