6 The moon Titan which orbits Saturn is known to have a dense atmosphere and lar
ID: 1033800 • Letter: 6
Question
6 The moon Titan which orbits Saturn is known to have a dense atmosphere and large pools of liquid methane rather than liquid water. Imagine that we evolved there instead of on earth, and assume a DNA like molecule is responsible for carrying genetic information in this scenario. Propose changes to the structure of DNA that would make it more likely to evolve in such a place with no liquid water, but liquid methane instead. Which of the weak interactions/forces required for biological life would be most affected and which would not? Why? Liquid ammonia is also thought to exist in large pools on Titan would this make biological life more or less similar to life on earth (relative to methane)? How so? What would be the effect of this environment on natural DNA? Why?Explanation / Answer
Nitrogenous base pairs are hydrophobic and are stacked inside the helix to minimize their contact with water; this base stacking stabilize the three dimensional structure of DNA. The backbone of DNA is hydrophilic and faces the surrounding water. The hydroxyl groups of the sugar residues form hydrogen bonds with water. In absence of water, these stabilizing base stacking and hydrogen bonds would not exist and the genetic material would not have the stable helical structure.
Also, hydrolysis and condensation reactions would not take place that lead to depolymerisation and polymerisation of DNA. Hence, in absence of water, DNA molecules would not have the structure as they have on earth in presence of water.
The H bonds are the weak interactions which stabilize most of the biomolecules as these biomolecules form H bond with surrounding water. In absence of water, these stabilizing H bonds would not exist and there would not be the stable folding of macromolecule
Liquid ammonia is also thought to exist in large pools on Titan would this make biological life more or less similar to life on earth (relative to methane). This is because ammonia allows H bond formation due to presence of H atom and electronegative nitrogen atom.
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