If the proportion of C in a double-stranded DNA molecule is x, what is the proportion of T?
A) x
B) x/2
C) 1 -x
D) ½ - x
E) 2x

Question

Quizplus · Accepted Answer

In double-stranded DNA, C always pairs with G and T always pairs with A. Thus, the proportion of T must be the same as the proportion of A, which is 1-x (since the sum of all proportions must equal 1). Therefore, the proportion of T is (1-x)/2, since there are two strands of DNA and each strand must have the same proportion of T. Simplifying this expression gives us choice D, 1/2 * (1-x).

If the Proportion of C in a Double-Stranded DNA Molecule