Question

List important features of Watson and Crick model of DNA.

Answer 1

Important features of the Watson–Crick model are:

1. DNA consists of two polynucleotide strands coiled into a double helix.
2. The strands are antiparallel: one runs [5'→3'] and the other [3'→5'].
3. The sugar–phosphate backbones form the outside of the helix; nitrogenous bases project inward.
4. Bases pair specifically: A pairs with T through two hydrogen bonds, and C pairs with G through three hydrogen bonds. This is complementary base pairing.
5. Each base pair joins one purine with one pyrimidine, maintaining a uniform helix width of about 2, nm.
6. One complete turn measures 3.4, nm and contains 10 base pairs; adjacent pairs are separated by 0.34,nm.
7. The two strands are complementary, so either strand can serve as a template for formation of its partner.

The model explains DNA’s stable structure, complementary replication and reliable transmission of genetic information.