Proteins - made of H, O, C, and N - formed by linking monomers called amino acids. - most important organic compound – body structure Amino Acids - 20 total, similar in structure but slightly different

- Carbon as the central atom with 4 other atoms or groups attached NH 2 -- amine group H C R group (what differs in all 20 ) C (Carboxyl group) O OH

Dipeptides – two amino acids joined by a peptide bond. - long chain of amino acids = polypeptide. - Protein = 2 or more polypeptides

Enzymes – proteins that act as catalysts substrate – molecule that attaches to the enzyme.

A catalyst lowers activation energy. Catalysts are substances that speed up chemical reactions. – decrease activation energy – increase reaction rate

Enzymes allow chemical reactions to occur under tightly controlled conditions. Enzymes are catalysts in living things. – Enzymes are needed for almost all processes. – Most enzymes are proteins.

Disruptions in homeostasis can prevent enzymes from functioning. –Enzymes function best in a small range of conditions. –Changes in temperature and pH can break hydrogen bonds. –An enzyme’s function depends on its structure.

An enzyme’s structure allows only certain reactants to bind to the enzyme. –substrates –active site substrates (reactants) enzyme Substrates bind to an enzyme at certain places called active sites.

Monomers and Polymers Carbohydrates – Monosaccharides Attach to form disaccharides and polysaccharides Proteins – Amino Acids Attach to form dipeptide and polypeptide molecules

Protein Function Enzymes Defense = Fights Cancer cells Transport = Hemoglobin transports oxygen Support = Keratin in hair, collagen in skin, bone Motion = Muscles Hormones = Growth hormones and insulin