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CIE Jun 2015 v2 Paper 4 Q7
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![12 Section B Answer all the questions in the spaces provided. This question is about the structures and roles of DNA and RNA in protein synthesis. (a) Study the structures of the three molecules below. One of the molecules could be a building block for a protein while the other two could be building blocks for other biological polymers. HO OH OH HO CH2OH O H OH OH OH HO OH NH2 Which of the three could be a building block for a protein? Explain your answer.[1] (b) Outline the different roles played by mRNA and tRNA in producing a protein with a speci c primary structure. mRNAtRNA[4]UCLES 2015 9701/42/M/J/15<br />
(c) Sickle cell anaemia is a genetic-based disease in which one of the glutamic acid residues is replaced by a valine residue. 13 HO OH NH2 glutamic acid OH NH2 valine Suggest and explain how this change in the primary structure of the protein would affect the overall structure and function of the protein.[3] [Total: 8]UCLES 2015 9701/42/M/J/15 [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/June_2015_v2_QP_-_Paper_4_CIE_Chemistry_A-level_7-0.jpg)
![Page 8 Cambridge International A LevelMay/June 2015 Mark Scheme Syllabus Paper 9701 42 (a) Lit is the only compound that is an amino acid or can form (NOT contain) NHCO / amide / peptide linkages / bonds or it contains an N atom / NH2 group / CO2H group (b) mark both parts of this togethermax [4] from the following six points M1 mRNA is complementary to or a copy of (a portion of) DNA M2 mRNA encodes the sequence of amino acids in proteins or each of its codons (base triplets) codes for one amino acid [1] [4] M3 mRNA binds to / associates with the ribosome M4 M5 M6 tRNAs are specific to their amino acids tRNA contains an anticodon or bonds to the codon / mRNA through base pairing or translates the RNA code into the amino acid sequence tRNA carries the amino acid to the ribosome/mRNA [3] [Total: 8] the pH of that area of the protein would change (c) max [3] from the following six points. M1 M2 protein becomes less hydrophilic / soluble or more hydrophobic M3 M4 M5 M6 fewer hydrogen bonds or more van der Waals (idid) forces fewer ionic bonds form the tertiary structure / folding / (3D) shape (of the protein) would change the active site would be different / less efficientCambridge International Examinations 2015<br />](https://learnah.org/wp-content/uploads/2018/08/June_2015_v2_MS_-_Paper_4_CIE_Chemistry_A-level_7.jpg)