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5. Answer ALL parts (a) to (f). Glycine and valine, respectively, are examples of naturally occurring amino acid molecules. H₂N-CH₂-COOH H₂N-CH(CH(CH3)2)-COOH glycine valine (a) Indicate the chiral centre of valine. Describe how measurements using a polarimeter can be used to distinguish between a sample of pure glycine and a sample of pure L-valine. [4%] (b) Draw the structures of the four possible dipeptides that may be formed when two molecules from a mixture of glycine and valine react together. [4%] (c) Draw the structures of glycine in aqueous solution at pH 2, pH 7 and pH 12, respectively. [3%] (d) Draw the repeating unit of the polymer that results from the condensation polymerisation reaction between the following monomers: HOOC–CH(C6H5)–COOH H2N-CH(CH3) NH2 dicarboxylic acid diamine [4%] (e) Name the general class of polymer to which the polymer formed in (d) belongs. [1%] (f) Draw the reaction profile (energy versus reaction progress) for a general uncatalysed chemical reaction passing through a single transition state. On the same diagram draw another reaction profile for a catalysed reaction. Comment on any differences between the two profiles. [4%]