Translation is a universal process in biology where a protein formed of amino acids is made by using messenger Ribonucleic acid (mRNA) to dictate the order of amino acids.
Following transcription (the conversion of DNA into mRNA) an mRNA strand leaves the nucleus and enters the cytoplasm via the nuclear pore. Here it is recognised and becomes attached to biological structures called ribosomes forming a 'polysome'. Each ribosome attached to an mRNA strand will create a seperate polypeptide.
The bases (individual components of mRNA) are read in non-overlapping 3s (a codon) by the ribosome. This is the 'triplet code'. Once mRNA has become attached the start codon is held in the peptidyl (P) site and the next codon in the aminoacyl (A) site. There is also an exit (E) site located on the other side of the P site. Synthesis occurs in a 5' to 3' direction of mRNA.
For amino acids to attach they are first conjugated (bonded) to a specific transfer RNA (tRNA), each tRNA has an anticodon which is complementary to a codon in the mRNA. The tRNA and mRNA are matched by codon to anticodon hydrogen bonding. This causes the conjugated amino acid to be positioned so it can be bonded to the previous amino acid by a peptide bond. The start codon, thus the first amino acid in a peptide is usually methionine.
The formation of the polysome and the attachment of methionine is known as the 'initiation' step.
Following initiation, the rest of the peptide is synthesised. The mRNA and tRNA-amino acid in the A site are pushed into the P site, forcing that in the P site into the E site and a new codon moves into the A site. At the E site the tRNA now without it's amino acid dissociates from the mRNA and goes to bind another amino acid, it is recycled. This is called 'elongation' and it repeats until a stop codon is reached. Causing the peptide chain to grow by one amino acid each cycle.
Once a stop codon arrives at the A site there is no matching amino acid. Instead a release factor protein triggers the disassembly of the ribosome-mRNA complex. This step is called 'termination'. Following this the protein is complete and is released by the ribosome.