During DNA replication, which bonds are broken to separate the two strands of the DNA double helix?

• A. Glycosidic bonds between each base and its deoxyribose sugar
• B. Peptide bonds between amino acids in histone proteins
• C. Hydrogen bonds between complementary nitrogenous bases
• D. Phosphodiester bonds between adjacent nucleotides in the sugar-phosphate backbone

Answer: (C)

Verified step by step guidance

1. Understand the structure of DNA: DNA consists of two strands forming a double helix, where each strand is made up of nucleotides connected by phosphodiester bonds in the sugar-phosphate backbone.
2. Identify the types of bonds present: Within each nucleotide, the base is attached to the sugar by a glycosidic bond; adjacent nucleotides are linked by phosphodiester bonds; and the two strands are held together by hydrogen bonds between complementary nitrogenous bases (A-T and G-C).
3. Recall the process of DNA replication: To replicate DNA, the two strands must be separated to serve as templates for new strands.
4. Determine which bonds must be broken to separate the strands: Since the sugar-phosphate backbone must remain intact for each strand to serve as a template, the bonds broken are the hydrogen bonds between complementary bases.
5. Conclude that the hydrogen bonds between nitrogenous bases are broken during DNA replication to separate the two strands, while glycosidic, phosphodiester, and peptide bonds remain intact.