You are a scientist on board on a mission exploring undersea volcanic vents arou

Question

You are a scientist on board on a mission exploring undersea volcanic vents around the Hawaiian Islands. On your expedition ship you have a fully equipped laboratory (like our new building will be) where you can do advanced microscopy, cellular biology and biochemical characterization of the life forms you encounter You encounter a NEW unicellular EUKARYOTIC organism This organism thrives in the following conditions: -The temperature is 78° C -The Oxygen content is extremely low -The sulfur content is very high, and it lives in complete darkness. -The organism and is capable of producing abundant ATP (but the mitochondria seem odd….) -The organism is capable of maintaining a resting potential of about -60 mV, and it also quickly eliminates xenobiotics using a co-transport mechanism depending on Na gradients. -This organism has the ability to “creep “ on the bottom of culture dishes using amoeboid like movements, and seems to be attracted to decaying organic matter (It creeps towards it !!!!) However if you constantly change the sea-water around the cells, they become “disoriented” and move randomly instead of towards the decaying piece of fish… Based on these observations, and what you have learned in this course and please discuss the following

1) What would be the composition of the cell membrane composition?

2) What type of energy metabolism would it it have?

3) What would the enzyme activity profiles in relation to temperature look like? pH (think about the environment it is in…)

4) How does it maintain a constant resting potential, and, use it for Xenobiotic transport?

5) Speculate on how these microorganisms detect the decomposing piece of shrimp…(or fish…)?

Explanation / Answer

1. Cell membrane composition of such salt tolerant organism would be abundance of diacidic phospholipid, archaetidylglycerol methylphosphate (PGP-Me), that would account for 50-80% of the lipids present on the membrane. It is evident from the above observation that these cells are more stable in concentrated salt solutions.

2. These are anaerobic sulfur oxidising organisms. These organisms oxidise hydrogen sulfide into various forms of sulfur.

3. With an increase in the pH , there would be an increase in the enzyme activity as this bacteria survives in higher temperatures, thus enzymes working in this bacteria would be highly thermostable. These enzymes can survive in neutral to acidic pH environments.

4. Enobiotics are eliminated using a co transport mechanism in which there is a movement of two molecules at a time. The energy that is not favoured for one molecule's movement is compensated by the energy favoured for the movement of the other molecule.

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