The DNA code for the protein remains in the nucleus, but a copy, called mRNA, moves from the nucleus to the ribosomes where proteins are synthesised in the cytoplasm. The protein produced depends on the template used, and if this sequence changes a different protein will be made.
Carrier molecules bring specific amino acids to add to the growing protein in the correct order. There are only about 20 different naturally-occurring amino acids.
Each protein molecule has hundreds, or even thousands, of amino acids joined together in a unique sequence. It is then folded into the correct unique shape. This is very important, as it allows the protein to do its job. Some proteins are enzymes, others are hormones and others form structures within the body, such as collagen. Each of these proteins needs a different shape.
Cells express their genes by converting the genetic message into protein. This process of protein synthesis occurs in two stages - transcription and translation.
When a gene is to be expressed, the base sequence of DNA is copied or transcribed into mRNA (messenger RNA). This process takes place in the nucleus and occurs in a series of stages.
After translation, the polypeptide is finally folded into the correct shape and becomes a protein. Peptide bonds form between the adjacent amino acids to finalise the structure.