More about proteins Proteins are the building block of our bodies. They make up many components (muscle, skin) or direct the synthesis of components (bone, hormones). Some proteins are enzymes that catalyze reactions. Chemical composition of a protein determines its shape and function.

Proteins are made of amino acids Proteins: polymers made of amino acids There are 20 amino acids. The 20 amino acids differ in size, shape, and chemical properties. Average protein is 300 amino acids –Neurotoxins: 10 or less amino acids –Muscle proteins: > 10,000 –Enzymes: ~ 300 amino acids

From DNA to proteins Genes direct the synthesis of proteins The sequence of DNA bases in a gene specify the sequence of amino acids in the corresponding protein. 3 bases (a codon) encode 1 amino acid