Complementary base pairing between strands of nucleic acids is limited to particular pairings because of
A) the relative sizes and shapes of purines and pyrimidines.
B) the alternating sugar-phosphate groups.
C) evolutionary relationships.
D) the differences found between RNA and DNA.
E) the diversity found in DNA molecules.

Question

Quizplus · Accepted Answer

Complementary base pairing is limited to pairing between purines (adenine and guanine) and pyrimidines (cytosine and thymine/uracil) due to their relative sizes and shapes. Purines are larger and have a double-ring structure, while pyrimidines are smaller and have a single-ring structure. These differences allow for the correct hydrogen bonding to occur between the complementary base pairs A-T/U and C-G. Therefore, option A is the correct choice.

Complementary Base Pairing Between Strands of Nucleic Acids Is Limited