CIE Nov 2014 v1 Paper 4 Q6

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14 Section B Answer all the questions in the spaces provided. PMT (a) A mixture of amino acids can be separated by electrophoresis. During an electrophoresis experiment,different amino acids move in different directions,different amino acids move at different speeds,some amino acids do not move at all. Explain these observations.[3] (b) (i) A mixture of amino acids can also be separated by thin-layer chromatography. Identify the mobile and the stationary phases in this type of chromatography. mobile phasestationary phase(ii) What is the process by which thin-layer chromatography can separate a mixture?[3] (c) State three structural features of DNA.[3]UCLES 2014 9701/41/O/N/14<br /> PMT 15 (d) Some diseases are caused by a mutation in the DNA base sequence which results in one amino acid being replaced by another during protein synthesis. Suggest what changes in the interactions that form the tertiary structure would result from a mutation that replaced a valine residue with a serine residue. NH CH C replaced by NH CH C HC CH3 CH3 val CH2 OH ser[2] [Total: 11]UCLES 2014 9701/41/O/N/14 [Turn over<br />

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