1) In the future, life is found on moons of Jupiter and Saturn: Enceladus, Calli
ID: 149852 • Letter: 1
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1) In the future, life is found on moons of Jupiter and Saturn: Enceladus, Callisto, and Ganymede. Curioush although the genetic material of these alien life forms is similar to DNA it uses different nucleotides with unusual properties, as described below. There is an RNA equivalent as well in both places. Assume replication proceeds in a similar fashion to that on Earth (including unidirectional polymerases, unless stated (7 points total) (0) Enceladus. The genetic material is single-stranded. (ii) Callisto. Here the genetic material is double stranded but a different type of nucleotide is used and the polarity of both strands is 5 to 3 (ili) Ganymede. Here the genetic material is more like that on earth with antiparallel nucleotide chains However, polymerases have evolved that can work both 3' to 5' as well as 5' to 3 (a) Will it be possible for origins of replication to be bidirectional in life from each location as they are for life with double-stranded DNA on earth, or must they be unidirectional A Uni B Bi (3 answers, one for each location, 1 point each) (b) Which proteins, equivalent to those in E. coli, would not be required specifically just to replicate an organism's genetic material in each place (assume origins fire in both directions if it is possible): A DNA polymerase lII B DNA polymerase I C Primase E DNA Ligase F Helicase G Topoisomerases (3 answers, one for each location, 1 point each) Pmhlen (c) Is the Ganymede scenario just u evolve to work 3' to 5 (assuming we are only using the standard type of nucleotides found in life on ean d it actuallExplanation / Answer
(a)
Enceladus - A (because genetic material is single-stranded)
Callisto - A (because the strands are parallel and run in only one direction)
Ganymede - B (similar to DNA on earth, the strands are anti-parallel and require bidirectional replication)
(b)
Enceladus - H (single-stranded material, so no H-bonding to any complementary strand like DNA on earth, therefore no helicase required to break the H-bonds).
Callisto - B (DNA Pol 1 is required when there are anti-parallel strands(for replication of the lagging strand), but here the strands are parallel and replication is unidirectional so no DNA Pol 1 required).
Ganymede - C (Since polymerases, in this case, have evolved to work in both directions, there is no requirement of a primer for the synthesis of lagging strand, so no primase required).
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