Role of the Triplet Code
Higher Tier Only
- A gene is a sequence of nucleotide bases in a DNA molecule that codes for the production of a specific sequence of amino acids, that in turn make up a specific protein
- The DNA nucleotide base code found within a gene is a three-letter, or triplet, code
- Each sequence of three bases (in other words, each triplet of bases) codes for one amino acid
- There are 20 different amino acids that cells use to make up different proteins
- For example:
- CAG codes for the amino acid valine
- TTC codes for the amino acid lysine
- GAC codes for the amino acid leucine
- CCG codes for the amino acid glycine
- CAC codes for the amino acids histidine
- The genetic code is universal, meaning that almost every organism uses the same code (there are a few rare and minor exceptions)
- This means that the same triplets code for the same amino acids in all living things (meaning that genetic information is transferable between species)
Protein synthesis
- Protein synthesis occurs in the cytoplasm of a cell
- However, DNA is too large to leave the nucleus
- Instead, another, smaller, molecule is used to transfer sections of the triplet code from the nucleus to the cytoplasm to be used in the formation of proteins
The triplet code diagram
DNA is made up of triplets of nucleotide bases; each triplet codes for an amino acid
