PCAT Biological Processes – DNA Polymerase
- Jan 23, 2018
- PCAT Question of the Day
DNA polymerase creates new DNA by adding complimentary nucleotides to a template strand from the original double-stranded DNA. If a section of the template strand had a ration of 3:2 of A:T bases, what is the ration of A:T in the newly synthesized complimentary strand of DNA?
D) cannot be determined
Click for Explanation
DNA polymerase matches complimentary bases to each base in the template strand. If the template strand has an A:T ratio of 3:2, then the complimentary strand must have an A:T ratio of 2:3 in order to match the complimentary bases with their correct paired nucleotide. That is, each A in the original strand will be matched with a T and vice versa.
A) 3:2, incorrect, This would be true if the complimentary strand matched A:A and T:T.
B) 1:1, incorrect, Complimentary strand bases are paired in the same ratio, but with T in the place of A.
C) 2:3, correct.
D) cannot be determined, incorrect, A:T must be matched with T:A on the complimentary strand.
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