A certain segment of DNA can be used as a molecular clock. Its rate of mutation is one mutation per 15 million years. Examine the DNA segments from two different species: Species A: GTTGAGCTAGTATGGACC Species B: GATAAGCTAGTAAGGTCA Using this example, explain how this information can be used to determine how long ago these two species shared a common ancestor.

Respuesta :

Species A: GĀ TĀ TĀ GĀ AĀ GĀ CĀ TĀ AĀ GĀ TĀ AĀ TĀ GĀ GĀ AĀ CĀ C
Species B: GĀ AĀ TĀ AĀ AĀ GĀ CĀ TĀ AĀ GĀ TĀ AĀ AĀ GĀ GĀ TĀ CĀ A
Differences: Ā  Ā 1 Ā  Ā 1 Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  Ā  1 Ā  Ā  Ā  Ā  1 Ā  Ā  1

In comparing the species, Ā I noticed 5 differences. I noted the differences using 1.Ā 

Since the problem states that 1 mutation occurs per 15 million years, it is safe to say that the two species shared a common ancestor 75 million years ago.

5 mutations * 15million yrs/mutation = 75 million years.