CIE Jun 2016 v3 Paper 4 Q7

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(a) (i) Use the Data Booklet to draw the structure of the tripeptide Ala-Ser-Gly showing its peptide bonds in full. 10 PMT Ala-Ser-Gly [2] (ii) Calculate the relative molecular mass, Mr, of Ala-Ser-Gly. Mr =[1] (b) Electrophoresis can be used to separate mixtures of amino acids and peptides. A mixture of the tripeptide Ala-Ser-Gly and its three constituent amino acids was subjected to electrophoresis in a buffer at pH 11. (i) Draw the structure of serine at pH 11. [1]UCLES 2016 9701/43/M/J/16<br /> PMT At the end of the experiment the following results were seen. 11 mixture applied here (ii) Identify the components labelled F-I in the above diagram. FGHI[4] (iii) Suggest the identities of the species responsible for spot P,spot S.Explain your answers.[3] (c) (i) State the reagents and conditions needed for converting the tripeptide into its three constituent amino acids.[1] (ii) Name the type of reaction in (i).[1] [Total: 13]UCLES 2016 9701/43/M/J/16 [Turn over<br />

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