MCAT Biochemistry Question 104: Answer and Explanation
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Question: 104
14. You have just sequenced a piece of DNA that reads as follows:
5′—TCTTTGAGACATCC—3′
What would the base sequence of the mRNA transcribed from this DNA be?
- A. 5′—AGAAACUCUGUAGG—3′
- B. 5′—GGAUGUCUCAAAGA—3′
- C. 5′—AGAAACTCTGTAGG—3′
- D. 5′—GGATCTCTCAAAGA—3′
Correct Answer: B
Explanation:
To answer this question correctly, we must remember that mRNA will be antiparallel to DNA. Our answer should be 5′ to 3′ mRNA, with the 5′ end complementary to the 3′ end of the DNA that is being transcribed. Thus, the mRNA transcribed from this strand will be 5′—GGAUGUCUCAAAGA—3′. mRNA contains uracil, rather than thymine.