Approximately half of the small insertions or deletions that are found in coding regions of DNA have lengths that are an exact multiple of 3. If the lengths of insertions or deletions in coding regions were completely random, what proportion would be expected to be an exact multiple of 3?
A)1/6
B)1/3
C)2/3
D)1/2
E)None of the answer options is correct.

Question

Quizplus · Accepted Answer

Given that there are three nucleotides per codon, any insertion or deletion that is a multiple of three will not disrupt the reading frame of the gene. Since there are three possible lengths for an insertion or deletion to be a multiple of 3 (i.e., 3, 6, 9, etc.), out of all possible lengths (1, 2, 3, 4, 5, 6, etc.), the probability of any random insertion or deletion being a multiple of 3 is 1 out of every 3 possibilities, or 1/3.

Approximately Half of the Small Insertions or Deletions That Are