MSP - biological molecules

describe the structure of starch

• polysaccharide of alpha glucose joined by glycosidic bonds

• branched molecule

describe the structure of glycogen

• polysaccharide of alpha glucose joined by glycosidic bonds

• highly branched molecule

describe the structure of cellulose

• polysaccharide of beta glucose joined

• every other beta glucose molecule is upside down

• each molecule forms a long straight chain

• many hydrogen bonds between chains, forming microfibrils

explain the function of starch/glycogen

• insoluble - doesn’t affect water potential

• branched/helical - compact/fits many in a small space

• polymer of glucose - provides glucose for respiration

• branched - many ends for enzymes to attach and hydrolyse

• large - cannot leave the cell

describe the structure of a triglyceride

• made up of 1 glycerol and 3 fatty acids

• molecules are joined by ester bonds

what is meant by a saturated fat?

single C-C bonds in the hydrocarbon chain

what is meant by an unsaturated fat?

double C=C bonds in the hydrocarbon chain, causing kinks

explain the function of triglycerides

• energy store - many C’s and H’s so there’s more energy per g than carbohydrates

• buoyancy - low density

describe the structure of dipeptides

• polypeptides formed by condensation reactions

• bond formed is called a peptide bond

• forms between amine roux of one amino acid and the carboxylate group of another

describe the stages of the hierarchical protein structure

• primary structure - polymer of amino acids joined by a condensation reaction in a specific order of amino acids in a polypeptide chain - peptide bonds

• secondary structure - polypeptide chain folds into either an alpha helix or beta pleated sheet - hydrogen bonds

• tertiary structure - polypeptide chain folds further to produce a specific 3d structure - hydrogen bonds/ionic bonds/disulphide bonds

• quaternary structure - more than one polypeptide chain folds further - hydrogen bonds/ionic bonds/disulphide bonds