The genetic underpinnings of a disease have recently been identified. This disease has been found...
The genetic underpinnings of a disease have recently been identified. This disease has been found to result from a single point mutation in the coding sequence of a gene. The normal coding sequence of this gene is 5' - GATTACG - 3'. Which of the following could be the disease-causing form of the gene?
- A. 5' - GATGATACG - 3'
- B. 5' - CGTAATC - 3'
- C. 5' - GATCACG - 3'
- D. 5' - GCATTAG - 3'
Correct Answer: C. 5' - GATCACG - 3'
Explanation
This question is essentially asking, Which of the following is a point mutation of the original sequence? A point mutation is a mutation in which one base pair of DNA is substituted for another. A point mutation will not change the reading frame of a DNA sequence because it does not involve adding or removing any bases. The only answer choice that is identical to the original sequence with the exception of one base pair being changed for another is 5'GATCACG3', so this is the correct answer.