Proteins C, H, N, O, S 50% of the Dry Weight of Living Organisms Function: 1. Structure  Hair, Fingernails, Cell membranes 2. Transport  Hemoglobin & Cell membranes 3. Regulatory  Protein Hormones 4. Catalysis  Enzymes 5. Locomotion  Muscles

Monomer General Structure Monomer = Amino Acids

Generalized Amino Acid Structure “Remainder Group” “Amine Group” “Acid Group”

“Dipeptide” = 2 amino acids R R In synthesis, one molecule loses an H+, one molecule loses an OH-. “Dipeptide” = 2 amino acids R R Peptide Bond

Peptide Bonds are POLAR, COVALENT Bonds

Proteins 22 different amino acids used to make all proteins Each has a unique “R” group! 9 of these not made by body  must come from diet Amino acids contain only C, H, N, O, S

What colour is the R group?

Levels of Organization Primary 1○ Amino acids linked together Peptide bonds join Forms POLYPEPTIDE chain

Secondary 2○ b/c peptide bonds are polar, H-Bonding routinely occurs between amino acids. Often, this will cause the chain coil up into a shape called an alpha helix. Layers called “ß-pleated sheets” can also form. Folded sheet OR Helical appearance

Tertiary 3○ different types of bonding (covalent, ionic, hydrogen) between -R groups makes the alpha helix bend and turn forms "globs" final 3-D shape is very exact and precise E.g. Enzymes

Quaternary 4○ More than one polypeptide arranged to take on unique structure E.g. Insulin / Hemoglobin

Denaturation of Proteins

Denaturation of Proteins Change in pH High heat Heavy metals High salt concentration Interfere with bonding of 2o & 3o structures Destroys shape of the protein