In double-stranded DNA, the amount of A equals that of T and the amount of C equals that of G because:
A)the strands wind around one another.
B)the strands have complementary sequences of bases.
C)pyrimidines always pair with each other, as do purines.
D)one strand runs 5' to 3' and the other 3' to 5'.

Question

Quizplus · Accepted Answer

The complementary base pairing between A and T, and C and G ensures that the amount of each base is equal in double-stranded DNA. This is because A always pairs with T and C always pairs with G, forming hydrogen bonds between the two strands. Therefore, if there is a certain amount of A on one strand, there must be an equal amount of T on the complementary strand, and the same goes for C and G.

In Double-Stranded DNA, the Amount of a Equals That of T