Proteins are made up of amino acids linked together by peptide bonds. The specific sequence and 3D structure of a protein determines its function. There are four levels of protein structure: primary structure is the amino acid sequence; secondary structure includes alpha helices and beta sheets from hydrogen bonding; tertiary structure is the overall folded shape from various weak interactions; and quaternary structure involves multiple protein subunits interacting.

4. Types of Amino Acids - H Gly/G Glycine Non-polar - CH 2 OH Ser/S Serine Uncharged Polar - (CH 2 ) 4 NH 4 Lys/K Lysine Basic - CH 2 COOH Asp/D Aspartic Acid Acidic R-Group Abbreviations Name Amino Acid Class