SCI Biology, DNA 2026 T2

DNA definition, function and structure

(Deoxyribonucleic Acid) is the genetic material found in living organisms.

1. Carrying genetic information for inheritance.

2. Coding for amino acids to produce proteins.

double helix (twisted ladder) structure made of two antiparallel strands. The sides are sugar-phosphate backbones and the rungs are complementary nitrogen base pairs held by weak hydrogen bonds.

Nucleotides and Nitrogen bases pairings

• subunits nucleotides. Each nucleotide contains:

  • a phosphate group

  • deoxyribose sugar

• Adenine (A) with Thymine (T)

• Cytosine (C) with Guanine (G)

DNA arrangement and terminology

strands are antiparallel, run in opposite directions. sugar and phosphate molecules form t

t

a