Question

The DNA double helix is stabilized primarily by:

• A. Covalent bonds
• B. Hydrogen bonds
• C. Ionic bonds
• D. Van der Waals forces

Hint:

Hydrogen bonds provide stability to DNA while still allowing strand separation during replication and transcription.

Answer 1

The Correct Option is B

The stabilization of the DNA double helix is primarily through hydrogen bonds. Let's understand the structure and bonding in DNA to determine why hydrogen bonds are the correct answer:

1. Structure of DNA: DNA consists of two strands that form a double helix. Each strand is made up of nucleotides, consisting of a sugar molecule, a phosphate group, and a nitrogenous base.
2. Base Pairing: The two strands of DNA are held together by specific base pairing:
   • Adenine (A) pairs with Thymine (T)
   • Guanine (G) pairs with Cytosine (C)
   This pairing occurs through hydrogen bonds.
3. Role of Hydrogen Bonds:
   • Each A-T pair is stabilized by two hydrogen bonds.
   • Each G-C pair is stabilized by three hydrogen bonds.
   These hydrogen bonds collectively provide the primary stability to the DNA double helix, allowing it to maintain its structure under various conditions.
4. Eliminating Other Options:
   • Covalent Bonds: While covalent bonds form the backbone of each DNA strand (between sugar and phosphate), they do not stabilize the helix structure between the two strands.
   • Ionic Bonds: These usually involve electrostatic attraction between charged particles and do not play a significant role in stabilizing the DNA double helix.
   • Van der Waals Forces: These are weak forces that contribute to stacking interactions between base pairs, but they are not as critical as hydrogen bonds in the stability of the helix.

In conclusion, the DNA double helix is primarily stabilized by hydrogen bonds between complementary bases on opposite strands. Therefore, the correct answer is:

Correct Answer: Hydrogen bonds