1. Extreme Environments Flashcards
Describe the unique features of archael lipids and membranes
- often found inhabiting extreme environments
- unique because; they are capable of methanogenesis and membrane lipids are linked
Detail the differences between peptidoglycan and pseudopeptidoglycan
Peptidoglycan - a complex polymer of sugars and amino acids; the substance from which bacterial cell walls are made
Pseudopeptidoglycan - a component of some cell walls of archaea
What structural feature of cell membranes is found in hypothermophylls
- high thermal stability; tetraether mono layer structure
What are the main structural differences between archaea and bacteria and what is their function
Archaea - methanogens have pseudo PG, chains of NAG + NAT, are linked by Beta 1,3 bond, acts as a selective barrier and is lysosome and Pc resistant
Bacteria - contain rigid PG sheets, chains of NAG + NAM, are linked by Beta 1,4 glycosidic bonds, tetrapeptide attached to NAM, peptide cross links to adjacent PG chain and is lysosome and Pc sensitive.
What mechanisms do halobacterium use to maintain cell wall stability and osmotic balance
Cell wall stability - glycoprotein stabilised by NA+ ions and depend on high NaCl concentration
Osmotic balance - internal water balance achieved by pumping K+ into cell, external K+ concentration lower so that water will diffuse osmotically into the cell and ribosomes require high K+ levels for stability.
Under what conditions do halophiles appear red in colour and why?
Under conditions of low aeration, absorption of light by bacteriorhodopsin gives cells their pinky/purple colour.
How do some halophiles produce energy under anaerobic conditions?
Via a unique type of photosynthesis wherein it uses the modified cell membrane and the absorption of light by bacteriorhodopsin to drive proton transport creating PMF for ATP synthesis.
List the name and maximum temperature of the most hyperthermophill organisms known
- Pyrolobus fumerii
- Tolerates temperatures of 90-113 degrees Celsius
What mechanism contributes to this property (high temp)
- protein heat stability; due to the folding of proteins, chaperoning involved (heat shock proteins), survives heat shock
Describe the symbiotic relationship between tube worms and vent bacteria
Bacteria provide giant tube worms with food in exchange for shelter - the bacteria use a process known as chemosynthesis to reap energy from hydrogen sullied to make organic compounds that the giant worm can eat.
