A portion of a sequencing gel is described as follows: the first band at the bottom of the gel was in the ddATP lane; the next band going up the gel was in the ddTTP lane, then the ddCTP lane, the ddGTP lane, the ddATP lane, the ddTTP lane, the ddCTP lane, the ddCTP lane, the ddATP lane, and the ddGTP lane. Which of the following is the correct sequence as determined on this gel?

Question

Quizplus · Accepted Answer

The sequencing gel indicates that the first band at the bottom of the gel was in the ddATP lane. This suggests that the first nucleotide in the sequence is an A.

Going up the gel, the bands are in the order ddTTP, ddCTP, ddGTP, ddATP, ddTTP, ddCTP, ddCTP, ddATP, and ddGTP. This suggests that the sequence is: 
ATCGATCCA

The sequencing gel also indicates that the first band at the top of the gel was in the ddGTP lane. This suggests that the last nucleotide in the sequence is a G.

Putting it all together, the correct sequence as determined on this gel is:
5' ATCGATCCAG 3'

Therefore, choice C is the correct answer.

A Portion of a Sequencing Gel Is Described as Follows