proteins

• proteins are polymers made from monomers of amino acids. when two amino acids bond a dipeptide is made. when more than two amino acids bond a polypeptide is made
• amino acids have the same general structure (a carboxyl group an amine group and an r group)
• all living things share a bank of 20 amino acids but their r groups are what make them different
• the primary structure of a protein is the order of amino acids that bond to make a polypeptide chain
• the secondary structure is alpha helixes and beta pleated sheets. they are held together by hydrogen bonds between polar molecules in a polypeptide chain
• tertiary structure is when the seconary structure is folded up to make a globular protein, hels in place by lots of weak hydrogen bonds, strong ionic bonds, disulphide bonds making a covalent bond (sulphur bridge)
• quaternary structure is several polypeptide chains that fit closely to make biologically active models. it is the way different polypeptide chains fit and how they are held in place by hydrogen, ionic and disulphide bonds.
• dipeptides and polypeptides are linked to amino acids by condensation reactions releasing a molecule of water. the bonds between amino acids are peptide bonds. the reverse hydrolysis reaction happens when di and polypeptides are brojen down
• the shape of a protein determines its function. there are lots of types of protiens and they all have different shapes and structures which relate to their jobs
• enzymes are tightly folded polypeptide chains and are soluble. they have roles in metabloism or they help synthesise molecules
• antibodies are immune responses and are found in the blood. two short and two long polypeptide chains
• transport protiens are channel proteins in cell membranes. they have hydrophobic and hydrophilic amino acids which fold up into channels. they transport ions and molecules across cell membranes
• structural proteins are physically strong, theyre made of long polypeptide chains parallel to each other. (keratin and collagen) collagen has 3 tightly coiled polypep chains