The shape of the DNA molecule is described as a double helix. This structure resembles a twisted ladder, where:
- Sugar and Phosphate Backbone: The sides of the ladder are made up of alternating sugar (deoxyribose) and phosphate groups, forming the structural framework.
- Base Pairs as Rungs: The rungs of the ladder are composed of nitrogenous base pairs, connected by hydrogen bonds. The base pairs follow complementary rules: adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).
The double helix structure, first discovered by James Watson and Francis Crick in 1953, is crucial for DNA’s function. It allows DNA to store genetic information compactly and replicate accurately during cell division.