Question

A double-stranded DNA molecule contains bases with a ratio of (A + T)/(G + C) = 3:1. This molecule is replicated with DNA polymerase in the presence of the four deoxynucleoside triphosphates with a molar ratio of (A + T)/(G + C) = 1:1. What is the expected ratio of (A + T)/(G + C) in the double-stranded daughter DNA molecule?

Answer 1

Answer:

3:1

Explanation:

DNA replication is a semi-conservative process of making the DNA copies of existing parental DNA strands. The process of DNA replication makes the complimentary copy of template DNA strand. Therefore, the ratio of (A + T)/(G + C) in parental DNA and daughter DNA double helices would be same.  

According to the question, the parent DNA strand has a ratio of (A + T)/(G + C) = 3:1. The daughter DNA molecules formed by replication of this parent DNA would also have (A + T)/(G + C) bases in 3:1 ratio.