A sequence of nucleotides that forms part of a DNA molecule (one DNA molecule contains many genes)
Protein
Molecules made up of a series of amino acids bonded together
Primary structure of a protein
The initial sequence of amino acids
Genes in DNA molecules
Control protein structure and function by determining the exact sequence in which the amino acids join together when proteins are synthesised in a cell
Triplet code
The sequence of DNA nucleotide bases found within a gene is determined by a triplet (three-letter) code
Codon
Each sequence of three bases (i.e. each triplet of bases) in a gene codes for one amino acid
Start and stop signals
Triplets of bases that code for start (TAC - methionine) and stop signals, telling the cell where individual genes start and stop
The genetic code is non-overlapping - each base is only read once in which codon it is part of
Degenerate genetic code
Multiple codons can code for the same amino acids
The degenerate nature of the genetic code can limit the effect of mutations
The genetic code is universal - the same triplet codes code for the same amino acids in all living things
The universal nature of the genetic code is why genetic engineering (the transfer of genes from one species to another) is possible
Anticodon
The complementary sequence to the codon on mRNA, found on tRNA molecules that transfer amino acids
