A segment of DNA from a lab mouse is determined to be 5’ – GGATCCTCATG – 3’. Which of the following DNA segments would be the result of this original DNA sequence experiencing both a point mutation and a deletion?
A) 5’ – GCATCCTCATG – 3’
B) 5’ – TGATCCCAG – 3’
C) 5’ – GGTCCTCATC – 3’
D) 5’ – GGATCCATG – 3’
Click for Explanation
A point mutation is one in which a single DNA base has be replaced by another and a deletion in one in which a single DNA base has been deleted. The question asks us to look for an answer choice that has had both a point mutation and a deletion. Only choice (C) matches these requirements.
A) 5’ – GCATCCTCATG – 3’
B) 5’ – TGATCCCAG – 3’
C) 5’ – GGTCCTCATC – 3’
D) 5’ – GGATCCATG – 3’
A, D: Neither (A) nor (D) has had any deletions at all – the length of the DNA chain is unchanged.
B: Two deletions have occurred as well as a point mutation. Both the 7th and 10th nucleotide are missing (both T).
Want more MCAT practice?
We’ve got options for every schedule and learning style!
Whether you need the flexibility of a Self-Paced Course, the instruction of a live 515+ Course, or the 1:1 attention of a private MCAT tutor, Blueprint MCAT has the MCAT prep option that works for your learning style!
Get started with a free MCAT diagnostic, one free practice exam, and tons more MCAT prep resources.
Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.
