2 Proteins

 

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Oxford Textbook Pages : 460 - 463

CGP Revision Guide Pages : 184 - 185

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Show Specification Ref : 3.3.13.2

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Question 1 / 5

AQA Jan 2010 Paper 4 Q6 areas outside the box will not be scanned for marking the three amino acids shown below were obtained by hydrolysis of a protein h n c cooh h n c cooh h n c cooh ch alanine ch ch ch ch nh valine lysine a i draw the zwitterion of alanine a ii draw the species formed when valine is dissolved in an alkaline solution mark a iii draw the species formed by lysine at low ph mark mark wmp jan chem b draw the two dipeptides formed by the reaction of alanine with valine areas outside the box will not be scanned for marking c name a suitable method by which the mixture of amino acids formed by hydrolysis of the protein can be separated mark marks turn over for the next question turn over wmp jan chem
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Question 2 / 5

AQA Jan 2010 Paper 4 Q8 section b answer all questions in the spaces provided areas outside the box will not be scanned for marking three isomers of c h no are shown below no no no no no no a i give the number of peaks in the c n m r spectrum of each isomer marks a ii draw the displayed formula of the compound used as a standard in recording these spectra mark wmp jan chem areas outside the box will not be scanned for marking b isomer x is prepared from nitrobenzene by reaction with a mixture of concentrated nitric acid and concentrated sulfuric acid the two acids react to form an inorganic species that reacts with nitrobenzene to form x b i give the formula of this inorganic species formed from the two acids and write an equation to show its formation marks b ii name and outline a mechanism for the reaction of this inorganic species with nitrobenzene to form x question continues on the next page marks turn over wmp jan chem areas outside the box will not be scanned for marking c isomer y is used in the production of the polymer kevlar y is first reduced to the diamine shown below h n nh c i identify a suitable reagent or mixture of reagents for the reduction of y to form this diamine write an equation for this reaction using h to represent the reducing agent marks c ii this diamine is then reacted with benzene l dicarboxylic acid to form kevlar draw the repeating unit of kevlar marks wmp jan chem c iii kevlar can be used as the inner lining of bicycle tyres the rubber used for the outer part of the tyre is made of polymerised alkenes areas outside the box will not be scanned for marking state the difference in the biodegradability of kevlar compared to that of rubber made of polymerised alkenes use your knowledge of the bonding in these polymer molecules to explain this difference marks extra space turn over for the next question turn over wmp jan chem
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Question 3 / 5

AQA Jan 2012 Paper 4 Q9 do not write outside the box many aromatic nitro compounds are used as explosives one of the most famous is methyl trinitrobenzene originally called trinitrotoluene or tnt this compound shown below can be prepared from methylbenzene by a sequence of nitration reactions ch o n no no a the mechanism of the nitration of methylbenzene is an electrophilic substitution a i give the reagents used to produce the electrophile for this reaction write an equation or equations to show the formation of this electrophile reagents equation marks a ii outline a mechanism for the reaction of this electrophile with methylbenzene to produce methylnitrobenzene marks wmp jan chem do not write outside the box b deduce the number of peaks in the c n m r spectrum of tnt mark c deduce the number of peaks in the h n m r spectrum of tnt mark d using the molecular formula c h n o write an equation for the decomposition reaction that occurs on the detonation of tnt in this reaction equal numbers of moles of carbon and carbon monoxide are formed together with water and nitrogen mark turn over for the next question turn over wmp jan chem
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Question 4 / 5

AQA Jun 2011 Paper 4 Q4 do not write outside the box the amide or peptide link is found in synthetic polyamides and also in naturally occurring proteins a i draw the repeating unit of the polyamide formed by the reaction of propanedioic acid with hexane diamine a ii in terms of the intermolecular forces between the polymer chains explain why polyamides can be made into fibres suitable for use in sewing and weaving whereas polyalkenes usually produce fibres that are too weak for this purpose marks marks extra space wmp jun chem do not write outside the box b i name and outline a mechanism for the reaction of ch ch cocl with ch nh name of mechanism mechanism b ii give the name of the product containing an amide linkage that is formed in the reaction in part b i mark c the dipeptide shown below is formed from two different amino acids marks ch cooh h n c c n c ch sh h o h h draw the structure of the alternative dipeptide that could be formed by these two amino acids question continues on the next page mark turn over wmp jun chem d the amino acids serine and aspartic acid are shown below do not write outside the box ch oh cooh h c cooh h c ch cooh nh serine nh aspartic acid d i give the iupac name of serine mark d ii draw the structure of the species formed when aspartic acid reacts with aqueous sodium hydroxide d iii draw the structure of the species formed when serine reacts with dilute hydrochloric acid mark mark d iv draw the structure of the species formed when serine reacts with an excess of bromomethane mark wmp jun chem
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Question 5 / 5

AQA Jun 2016 Paper 4 Q5 do not write outside the box proteins contain sequences of amino acids joined by peptide links amino acid chains polypeptides are attracted to each other by hydrogen bonding a i a section of a protein is formed from one molecule of each of the amino acids glycine h nch cooh and alanine h nch ch cooh add bonds and atoms to the diagram to complete a structural formula for this section of the protein marks a ii draw a diagram to show how an amino acid chain can form a hydrogen bond with another amino acid chain your diagram need only show the relevant atoms from one amino acid in each chain mark wmp jun chem do not write outside the box b leucine serine and glutamic acid are naturally occurring amino acids ch chch nh cooh hoch nh cooh hooc ch nh cooh leucine serine glutamic acid b i give the iupac name of leucine mark b ii draw the structure of the zwitterion of serine b iii draw the structure of the ester formed by two molecules of serine b iv draw the structure of the species formed by glutamic acid at low ph mark mark mark turn over wmp jun chem
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