What best describes base pairing in DNA?

What best describes base pairing in DNA?

• A. The process of producing proteins from RNA
• B. The specific pairing of bases A with T and C with G
• C. The unwinding of the DNA double helix
• D. Enzymatic replication of DNA

Answer: (B)

Base pairing is the specific pairing of complementary bases across the two DNA strands, A with T and C with G. This rule ensures the two strands fit together with a consistent width, since purines pair with pyrimidines. Hydrogen bonds stabilize these pairs—A-T forms two bonds and C-G forms three—giving the DNA double helix its stability. This complementary pairing underpins accurate DNA replication, because each strand can serve as a template for creating a new partner strand with the correct base on every position. It also aligns with Chargaff’s rules, which state that A equals T and C equals G across the molecule. The other descriptions refer to different processes: producing proteins from RNA describes translation, unwinding the helix refers to helicase activity, and replication is the broader process that includes base pairing but is not itself the pairing rule.

Base pairing is the specific pairing of complementary bases across the two DNA strands, A with T and C with G. This rule ensures the two strands fit together with a consistent width, since purines pair with pyrimidines. Hydrogen bonds stabilize these pairs—A-T forms two bonds and C-G forms three—giving the DNA double helix its stability. This complementary pairing underpins accurate DNA replication, because each strand can serve as a template for creating a new partner strand with the correct base on every position. It also aligns with Chargaff’s rules, which state that A equals T and C equals G across the molecule. The other descriptions refer to different processes: producing proteins from RNA describes translation, unwinding the helix refers to helicase activity, and replication is the broader process that includes base pairing but is not itself the pairing rule.