Question

A team of scientists is studying a mitochondrial DNA sequence shared by two species, and they determine that the DNA has a constant mutation rate. The DNA sequences of the two species are shown below.

Species A: GTAGGCATTCGAT
Species B: GCACGCATACGTT

The scientists use the idea of molecular clocks to determine that the two species diverged from a common ancestor 40 million years ago. Based on this information, how much more time would it take for the two species to differ by a total of 10 base pairs?

80 million years
200 million years
60 million years
40 million years

Answer 1

i think its 60 million

Answer 2

The correct answer would be 60 million years.

The molecular clock is a technique used to determine the time when the two species diverged from a common ancestor. It uses the mutation rate to determine the same.

Mutation rate is the rate at which a number of mutations take place in a given unit time.

If we compare the DNA sequence of the given two species, we would find that four mutations have taken place in forty million years.

Species A: GTAGGCATTCGAT

Species B: GCACGCATACGTT

Thus, the mutation rate of the species is one mutation per 10 million years.

The DNA sequences already have 4 mutations. Thus, for a total of 10 mutations, 6 mutations are required.

Thus, in 60 million years the two DNA sequences would differ by a total of 10 nucleotides.