Question

DNA is synthesized by covalently linking a nucleotide to the previous nucleotide, constantly adding to a growing chain. The new strand becomes part of a stable double helix. The two strands are complementary in sequence and anti-parallel in directionality. What is the principal force that holds these two strands together?

a. ionic interactions
b. hydrogen bonds
c. covalent bonds
d. peptide bonds
e. Pauling bonds

Answer 1

The principal force that holds the two complementary and anti-parallel strands of DNA together is hydrogen bonding, which stabilizes the double helix structure.

Step-by-step explanation:

The principal force that holds together the two strands of a DNA molecule is due to the hydrogen bonds that form between the complementary nitrogenous bases on each strand. These two strands of DNA, which consist of bonding nucleotides with a deoxyribose and phosphate backbone, are oriented in an anti-parallel fashion. They connect via the hydrogen bonds between adenine and thymine, and guanine and cytosine, creating the stable double helix structure that is characteristic of DNA. Although hydrogen bonds are weaker than covalent bonds, their cumulative effect over millions of connections provides substantial stability to the DNA molecule, whilst also allowing for the necessary separation of the strands during DNA replication.