The base-pairing rules in DNA describe how nitrogenous bases form specific pairs between the two strands of the DNA molecule.
Here’s the rule:
- Adenine (A) always pairs with Thymine (T)
- Guanine (G) always pairs with Cytosine (C)
These pairs are held together by hydrogen bonds:
- A–T pairs form two hydrogen bonds
- G–C pairs form three hydrogen bonds
Explanation:
- The pairing is complementary, meaning the sequence of bases on one strand determines the sequence on the other.
For example, if one strand is A–T–G–C, the complementary strand will be T–A–C–G. - This ensures the DNA double helix structure is stable and can be accurately copied during DNA replication.
Summary:
A ↔ T (2 hydrogen bonds)
G ↔ C (3 hydrogen bonds)