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.

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.

anonymous · Answer

LOL... you!

anonymous · Answer

ur the best person for this question.
I have seen some of your answers about molecular clock

anonymous · Answer

and it helped me greatly!

blues · Answer

Yup, me. :D

All DNA is subject to mutations - random base pair substitutions, insertions and deletions over time. It turns out that the rate at which different regions of DNA undergoes mutations is different in the same organism and between different organisms. Also, different types of mutations occur at different rates.

A molecular clock is a specific region of DNA which undergoes substitution but not insertion / deletion mutations, and which is subject to mutations at the same rates in different species. It is also necessary that mutations in sequences used as molecular clocks do not affect the fitness of the organism to survive - they are so called "neutral" mutations.

By comparing the number of random mutations which have occurred in a molecular clock in different species - that is, seeing how different the sequences are - it is possible to infer how long ago the species diverged.

anonymous · Answer

The answer is in the last paragraph..
lol

blues · Answer

Yup, it is. In the sequences given I count five differences. You should check that because my computer is better at sequence alignment than I am.

You have to be just a little careful when actually computing this because sometimes the same mutation occurs at the same site and sometimes back mutations occur - both of which make the sequences look similar when in fact they are not. The key is that this will always give you an underestimate of the time since the organisms diverged, since it makes the sequences look more similar and closely related.

anonymous · Answer

I have no problems with all of that actually, I just have problems looking at those letters. xD

anonymous · Answer

Thanks for answering!

blues · Answer

I hear that. Textbook problems, we have to count. Real world, give it to the computer and let the computer count.

Not a prob - I like answering good questions.