Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine. This arrangement ________.

Question. Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine. This arrangement ________.

Select one:

1:- prevents accidental unwinding of the molecule

2:- permits complementary base pairing

3:- provides for instability in the molecule

4:- allows the nitrogenous bases to form the backbone of the molecule

5:- allows the molecule to more easily unwind during replication

Answer:- The correct option is 2. permits complementary base pairing

In a given DNA molecule, the nitrogenous bases on complementary strands are paired specifically via hydrogen bonding – adenine pairs only with thymine and cytosine binds exclusively with guanine.

This complementary base pairing allows the stability of the DNA double helix. It enables the two strands to match and join correctly through corresponding base pairs.

The other options are incorrect:

The mere idea of complementary base pairing does not stop accidental unwinding or stability in the options (1 and 3).

For option 4, the sugar-phosphate groups and not the nitrogenous bases form the backbone of DNA molecule.

Complementary pairing reinforces the double helix and makes unwinding more stable; it does not facilitate minimum of unthreading during replication (option 5 ).

Therefore, the complementary adenine-thymine and cytosine guanines religate allowing for precise pairing of both DNA strands as well as a stable formation of deoxyribose nucleic acid double helix (NIH, 2024).