Which type of bonds stabilizes the DNA base pairs and allows strands to separate during replication?

• A. Covalent bonds
• B. Ionic bonds
• C. Hydrogen bonds
• D. Metallic bonds

Answer: (C)

Hydrogen bonds between the bases are what stabilize the DNA base pairs and also allow the strands to separate during replication. The two strands stay together because complementary bases pair up through these relatively weak bonds—A pairs with T using two hydrogen bonds, and G pairs with C using three. Because hydrogen bonds are weaker than covalent bonds, enzymes like helicase can break them to unzip the double helix so replication can occur, then new bonds can form as the strands are copied. The backbone of DNA is held together by covalent bonds, which are much stronger and remain intact during replication, so the separation focuses on breaking the hydrogen bonds between bases. Ionic or metallic bonds don’t play a role in stabilizing DNA in this way.