DNA, genes and chromosomes
DNA - deoxyribonucleic acid. This molecule consists of two long chains of chemicals; nucleotides that twist around each other in a double helix.
- DNA can be copied or 'replicated' - each strand acts as a template for the generation of the complementary strand.
- Each nucleotide contains one of four nitrogen-containing bases: adenine (A), thymine (T), cytosine (C) and guanine (G).
- The sequence of these bases constitutes the genetic code - that specifies the order and number of amino acids in a protein.