1. Proteins most diverse and important molecules in most diverse and important molecules in living organisms living organisms coded for by DNA coded for by DNA structural building blocks for most living structural building blocks for most living functions functions made of long polymers of amino acids made of long polymers of amino acids

2. Types of Proteins TypeExample ► Structuraltendons, cartilage, hair, nails ► Contractilemuscles ► Transporthaemoglobin, myoglobin ► Storagemilk, nuts, seeds ► Hormonalinsulin, growth hormone ► Enzymecatalyses biochemical reactions ► Protectionimmune response (antibodies)

3. Amino Acids ► organic molecule made of a central C atom attached to an amino group, carboxyl group, H atom and a R group

4. ► 20 different R groups = 20 different a.a. ► simplest a.a., glycine, has H atom for R group ► R group determines nature of a.a., some are hydrophobic or hydrophilic

6. Essential Amino Acids ► 10 not synthesised by body ► arg, his, ile, leu, lys, met, phe, thr, trp, val ► Must be obtained from diet ► All in dairy products, meat, fish, eggs ► 1 or more missing from grains/vegetables ► Some plants; quinoa, buckwheat, hempseed & amaranth have nearly all

7. Peptide Bond ► Formed by bond between COOH of 1 st amino acid & NH 2 of 2 nd ► Several amino acids joined together make up a peptide chain

8. Protein Structure Primary Structure (1 o ) – the particular sequence of amino acids that is the backbone of a peptide chain or protein

9. Secondary Structure (2 o ) - coils and folds in polypeptide from H bonds between H and O atoms ► α helix – tight coil stabalized by H bonds ► β-pleated sheet – two polypeptide chains run parallel connected by H bonds

10. Tertiary Structure (3 o ) – supercoiling of polypeptide, due to attraction between secondary structures (cysteine a.a. attract each other forming disulphide bridges)

11. Quaternary Structure (4 o ) – two or more polypeptides forming a functional protein ► ex haemoglobin – 4 polypeptide chains, 2 α- chains, 2 β-chains, each surrounding a heme group (contains iron)

12. Denaturation ► proteins can only work under certain temp, pH, salt… ► denaturation changes bonds that hold 2 o, 3 o, 4 o changing protein’s function ► Causes: heat, pH, heavy metals ► Examples: cooking food, straightening/curling hair, alcohol denaturing bacteria