Question

What are the base-pairing rules for DNA?

Options

• A-G, T-C

• A-T, G-C

• A-U, C-G

• A-C, T-G

Answer 1

A-T, G-C

Explanation:

In the DNA double helix, adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C). A–T pairs form two hydrogen bonds while G–C pairs form three, and purine bases pair with pyrimidine bases to maintain a uniform helix. This is the basis of Chargaff’s rules and the Watson–Crick model.