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CIE Jun 2013 v2 Paper 4 Q6
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![Examiners For Use 13 Section B Answer all the questions in the spaces provided. There are two important polymerisations that occur within living organismsprotein synthesis and the formation of DNA. (a) Complete the table by placing a tick ( ) in the correct column to indicate in which process (cid:22) each substance could be used. protein synthesis formation of DNA substance cysteine cytosine glutamine guanine [3] (b) DNA consists of a double helical structure. (i) Describe the bonding between the two strands in DNA and state which part of each strand is joined by it.(ii) How does the strength of this bonding relate to the mechanism of the replication of DNA?[4] (c) Some diseases are caused by changes in the structure of proteins. Explain the genetic basis of these changes.[3] [Total: 10]UCLES 2013 9701/42/M/J/13 [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/June_2013_v2_QP_-_Paper_4_CIE_Chemistry_A-level_6.jpg)
![Page 10 (a) Mark Scheme GCE A LEVELMay/June 2013 Syllabus 9701 Paper 42 substance protein synthesis formation of DNA cysteine cytosine glutamine guanine (cid:1) (cid:1) (cid:1) (cid:1) (b) (i) Hydrogen bonding Between bases or between A,T, C and G (all four needed) (ii) Bonds are (relatively) weak or easily broken This enables strands to separate or DNA to unzip/unwind/unravel. (c) changes / mutations in DNA [3] [3] [1] [1] [1] [1] [4]by the addition / insertion /deletion / substitution / replacement of a baseadds / deletes / replaces an amino acid or changes the amino acid sequencethis causes a loss of function or changes the shape / tertiary structure of the protein any three points [3] [3] [Total: 10]Cambridge International Examinations 2013<br />](https://learnah.org/wp-content/uploads/2018/08/June_2013_v2_MS_-_Paper_4_CIE_Chemistry_A-level_6.jpg)