Proteins

Proteins are made of amino acids. There are 20 different amino acids, and they can bind together to form long chains with hundreds of amino acids. The properties of a protein are decided by what amino acids the protein is made of, and the order of the amino acids.

When the cells make new proteins, three and three base pairs in the DNA, called codons, are a code for a specific amino acid. The four bases in the DNA can make 64 codons, and the 20 amino acids have more than one code each. Some codons work as start or stop signals.