Complementary base pairing

Definition

Complementary base pairing is the specific hydrogen bonding between purines and pyrimidines in DNA. Adenine pairs with thymine, and guanine pairs with cytosine.

5 Must Know Facts For Your Next Test

1. Adenine (A) always pairs with thymine (T) through two hydrogen bonds.
2. Guanine (G) always pairs with cytosine (C) through three hydrogen bonds.
3. Complementary base pairing is essential for the double helix structure of DNA.
4. Errors in complementary base pairing can lead to mutations during DNA replication.
5. This principle is critical for processes like DNA replication and transcription.

Review Questions

• Which bases pair together according to the rules of complementary base pairing?
• How many hydrogen bonds connect adenine and thymine? How about guanine and cytosine?
• Why is complementary base pairing important for DNA replication?

Related terms

Hydrogen Bonding: Type of weak chemical bond that occurs between a hydrogen atom and a more electronegative atom.

Purines: Double-ring nitrogenous bases in DNA; includes adenine and guanine.

Pyrimidines: Single-ring nitrogenous bases in DNA; includes cytosine and thymine.