Biology Question

Question

A replicative DNA polymerase makes one error for every million nucleotide incorporations on average. If the genome is 1 billion base pairs, how many mutations will be introduced into genome on average? (In your calculation, note that each basepair is composed of two nucleotides.)

Answer 1

Sophie,

So first, as the question states, let's note that the genome is comprised of 2 billion nucleotides, as each of the billion base pairs has 2 nucleotides. Now, since we know the total size of the genome and the error rate of DNA polymerase, we can turn it into a simple arithmetic problem.

There is going to be 1 error for every 1 million nucleotides. Therefore, how many sets of 1 million are in 2 billion?

1,000,000(x)=2,000,000,000

2,000,000,000/1,000,000=x

x=2,000

So, we know that there are 2,000 errors in a genome of that size.