Question

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. Be sure to answer this question in paragraph form using complete sentences.

Answer 1

Answer and explanation;

• This can be done by DNA sequencing which is the process of determining the accurate order of nucleotides within a DNA molecule.
• By doing a DNA sequencing for the two sequences of DNA from the two species it will help compare the number of random mutations which have occurred in a molecular clock in the two species - that is, seeing how different the sequences are.
• This will make it possible to infer how long ago the species diverged.

Species A: GTTGAGCTAGTATGGACC

Species B: GATAAGCTAGTAAGGTCA

These species differ in 5 nucleotides.

This number should be multiplied by the rate of mutations; that is;

5 × 15 million years =75 million years.