L7 Archaea and life in the extreme Flashcards
What kind of environments are archaea often associated with
Extreme
What is likely to happen to the 3 domains of life tree as science evolves
Likely adapted into just 2 branches
What is a characteristic component of archaeal cell walls
S-layer
What is the role of the S-layer
Protection in harsh conditions
Are archaea gram positive or gram negative
Can be either
Give some examples of the metabolic processes carried out by archaea
Variant Entner-Doudorff, EMP pathways, metahnogenesis
Do any other microbes produce methane through their energy production
No, just archaea
Do archaea ususually have a cell wall
No
What is most flexible: S-layer, peptidoglycan, double mmebrane structures
S-layer
What is their range of growth temperature
-20 to 120 C
Is sulphur metabolised anaerobically or aerobically
Both
What temperature do Thaumarchaeota occur
Ambient - cold temperatures
How many routes are there which produce methane for energy
Numerous
What compounds are involved in the most common methanogenesis mechanism
Carbin dioxide and hydrogen to methane and water
Does methanogenesis have a high or low yield of energy
Low
-∆G˚’
Which environments can methanogens be found in
Wetlands
Paddy fields
Landfill
Polar permafrost
Animals (agriculture)
Sewage treatment
Marine sediments
How do wetlands create an environment for methanogenesis
Rich in organic matter broken down by bacteria, poor oxygen diffusion creates anaerbic conditions
How can polar permafrost create an ideal environment for methanogens
Retreating glaciers could cause mass release of methane as long term stored biomass will be exposed in wet conditions (ideal for methanogenesis)
How is an extreme environment defined
Conditions damaging to most forms of life - often human centric
What are some challenges of extreme cold
Enzyme mediated reactions are slower
Membranes become less fluid, reduce nutrient transport
Cold liquids are mroe viscous
Water freezes and causes ice crystals which are sharp and can pierce membranes
What are some psychrophilic adaptations
Membrane fluidity increased
Cryoprotectant compounds
Low temp enzyme optima
How can membrane fluidity be increased
Increase unsaturated and methyl branched fatty acids change to looser packing
More bonds = less rigid
Give an example of cryoprotectant compounds
Anti-freeze proteins
Trehalose
How can enzymes have a lower optimum temp
Increased flexibility due to reduced bonding between peptide chains, more accessible active site, amino acid selection
