Proteins are large molecules that perform tasks in the body which are critical for life. For example, they build muscles, structural proteins (for producing the essential structural components of a cell), vital enzymes and hormones. Proteins are long chains consisting of 40 to 400 individual building blocks. There are 20 different such basic building blocks, the so-called amino acids. The order of these amino acids referred to as the sequence of a protein is determined by the genes. Each protein building block gives the molecule different properties.