In the double-stranded structure of DNA,
A) the two strands are held together by covalent bonds.
B) the monomers in each strand are linked together by hydrogen bonds.
C) both strands run in the same direction.
D) the two strands are held together by hydrogen bonds.
E) the monomers in each strand are linked together by ionic bonds.

Question

Quizplus · Accepted Answer

The two strands of DNA are held together by hydrogen bonds between complementary nitrogenous bases (adenine with thymine, and guanine with cytosine). The monomers within each strand are linked together by covalent phosphodiester bonds. The strands run antiparallel to each other, meaning the 5' end of one strand is paired with the 3' end of the other. Therefore, choices A, B, and E are incorrect.

In the Double-Stranded Structure of DNA