Proteins are large organic compounds which are made up of amino acids which are arranged in a certain way by peptide bonds to the carboxyl and amino groups. The arrangement of amino acids determines the shape of a protein, and the shape of the protein determines the function. The arrangement of amino acids depends on the genes and the genetic code.


Some notes about enzymes:
Enzymes act as catalysts, which means that they speed up the rate at which reactions happen. They are not used up by the reaction, so they can catalyze many reactions without being changed. The lock and key model explains that each enzyme is specific for the substrate they work on.