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The proinsulin molecule is made of 3 peptide chains (A,B, and C) whereas the act

ID: 18910 • Letter: T

Question

The proinsulin molecule is made of 3 peptide chains (A,B, and C) whereas the active insulin molecule is made up of just the A and B chain. Rates of mutation have been measured for each chain. The observed rate of mutation of the C peptide chain is greater than the mutation rate of the A and B chain. This pattern is best explained by:

a) The C peptide is not translated thus mutations build up

b) Selection causes greater mutation within the C chain

c) While mutations occur in the A and B chains they have no effect

d) All of the above

e) None of the above

Explanation / Answer

c) While mutations occur in the A and B chains they have no effect