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?
A. 3:2
B. 1:1
C. 2:3
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.
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.
