What is the role of hydrogen bonds in the structure of DNA?

• A. They form the covalent backbone of the DNA molecule by linking deoxyribose sugars and phosphate groups.
• B. They catalyze the replication of DNA by stabilizing DNA polymerase.
• C. They hold the two complementary strands of the DNA double helix together by connecting nitrogenous bases.
• D. They attach the DNA molecule to histone proteins in chromatin.

Answer: (C)

Verified step by step guidance

1. Understand the structure of DNA: DNA is a double helix composed of two complementary strands. Each strand consists of a sugar-phosphate backbone and nitrogenous bases that pair with bases on the opposite strand.
2. Learn about hydrogen bonds: Hydrogen bonds are weak interactions that occur between a hydrogen atom covalently bonded to an electronegative atom (like oxygen or nitrogen) and another electronegative atom. These bonds are crucial for stabilizing molecular structures.
3. Identify the role of hydrogen bonds in DNA: Hydrogen bonds connect the nitrogenous bases of the two complementary strands. Adenine (A) pairs with thymine (T) via two hydrogen bonds, and cytosine (C) pairs with guanine (G) via three hydrogen bonds.
4. Clarify why hydrogen bonds are important: These bonds hold the two strands of the DNA double helix together, ensuring the stability of the structure while allowing the strands to separate during processes like replication and transcription.
5. Eliminate incorrect options: Hydrogen bonds do not form the covalent backbone, catalyze replication, or attach DNA to histone proteins. Their primary role is to connect nitrogenous bases and stabilize the double helix.