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8/26/2020

Oxford University Press | Online Resource Centre | Chapter 02

Patrick: An Introduction to Medicinal Chemistry 6e

Chapter 02

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You have answered 0 out of 13 questions correctly. Your percentage score is 0%. Question 1 Identify the correct name for the following peptide.

Your answer: d) L-alanyl-glycyl-L-phenylalanine Correct answer: a) L-alanyl-L-phenylalanyl-glycine Feedback: Peptides are named, starting from the amino end. Option b) is wrong since it is named from the carboxyl end. Options c) and d) are wrong since the amino acids are labelled in the wrong order. Page reference: 17-18

Question 2 Which of the following single letter codes represents the structure below?

You did not answer the question. Correct answer: b) ASGYVD Feedback: The order of the amino acids from the N-terminal end of the peptide is alanine (A), serine (S), glycine (G), tyrosine (Y), valine (V) and aspartic acid (D). Option a) is wrong since the amino acids are labelled from the C-terminal end. Option d) is wrong since it mislabels tyrosine as phenylalanine, and aspartic acid as glutamic acid. Option c) has the same mistakes as option d) and is also labelled from the wrong end. Page reference: 17-18

Question 3 Which of the following statements is true about a peptide bond (RCONHR')? You did not answer the question. Correct answer: https://global.oup.com/uk/orc/chemistry/patrick6e/student/mcqs/ch02/

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Oxford University Press | Online Resource Centre | Chapter 02

b) It is capable of forming a hydrogen bond. Feedback: Statement b) is correct. The NH of the amide can act as a hydrogen bond donor and the carbonyl group can act as a hydrogen bond acceptor. Statements a), c) and d) are false. The peptide bond has double bond character due to the interaction of the nitrogen lone pair with the carbonyl group. This prevents bond rotation and makes the bond planar. The trans isomer is favoured over the cis isomer. Page reference: 17-18

Question 4 Which of the following statements is untrue about protein secondary structure? You did not answer the question. Correct answer: d) The hydrophilic/hydrophobic character of amino acid residues is important to secondary structure. Feedback: The hydrophilic / hydrophobic character of amino acid residues is important to protein tertiary structure rather than to secondary structure. In secondary structure, it is the steric size of the residues that is important and residues are positioned to minimise interactions between each other and the peptide chain. Page reference: 18-19

Question 5 Identify which of the following terms refers to the arrangement of different protein subunits in a multiprotein complex. You did not answer the question. Correct answer: d) quaternary structure Feedback: Primary, secondary and tertiary structure refer to the different structural levels of a single protein. Quaternary structure refers to the overall structure of a multiprotein complex. Page reference: 23-24

Question 6 Identify which of the following terms refers to the order in which amino acids are linked together in a protein. You did not answer the question. Correct answer: a) primary structure Feedback: Primary structure refers to the order of the amino acids in a protein. Secondary structure indicates regions of ordered structure, and tertiary structure is the overall structure of the protein. Quaternary structure refers to the structure of a multi-protein complex. Page reference: 17-18

Question 7 Identify which of the following terms refers to the overall three dimensional shape of a protein. You did not answer the question. Correct answer: c) tertiary structure Feedback:

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Primary structure refers to the order of the amino acids in a protein. Secondary structure indicates regions of ordered structure, and tertiary structure is the overall structure of the protein. Quaternary structure refers to the structure of a multi-protein complex. Page reference: 19-21

Question 8 Identify which of the following terms refers to 'regions of ordered structure within a protein'. You did not answer the question. Correct answer: b) secondary structure Feedback: Primary structure refers to the order of the amino acids in a protein. Secondary structure indicates regions of ordered structure, and tertiary structure is the overall structure of the protein. Quaternary structure refers to the structure of a multi-protein complex. Page reference: 18-19

Question 9 Identify the strongest form of intermolecular bonding that could be formed involving the residue of the amino acid serine. You did not answer the question. Correct answer: b) hydrogen bond Feedback: Serine contains a hydroxyl functional group on its side chain and so the strongest possible interaction will be hydrogen bonding where the hydroxyl group could act as a hydrogen bond donor or hydrogen bond acceptor. Page reference: 21-23

Question 10 Identify the strongest form of intermolecular bonding that could be formed involving the residue of the amino acid valine. You did not answer the question. Correct answer: c) van der Waals interactions Feedback: Valine has no functional groups on its side chain. There is only an alkyl group and so only van der Waals interactions are possible. Page reference: 21-23

Question 11 Identify the strongest form of intermolecular bonding that could be formed involving the residue of the amino acid glutamic acid You did not answer the question. Correct answer: a) ionic bond Feedback: Glutamic acid contains a carboxylic acid functional group which could act as a hydrogen bond donor or hydrogen bond acceptor. However the group could lose its acidic proton to gain a negative charge allowing a stronger ionic interaction to take place. Page reference: 21-23

Question 12 Identify the strongest form of intermolecular bonding that could be formed involving the residue of the amino acid tyrosine. https://global.oup.com/uk/orc/chemistry/patrick6e/student/mcqs/ch02/

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You did not answer the question. Correct answer: b) hydrogen bond Feedback: Tyrosine contains an aromatic ring and a phenol group. The aromatic ring could form van der Waals interactions, but the phenol group could form stronger hydrogen bonds as a hydrogen bond donor or hydrogen bond acceptor. Page reference: 21-23

Question 13 Which of the following statements is incorrect regarding transport proteins? You did not answer the question. Correct answer: d) They are required to transport hydrophobic steroids across cell membranes. Feedback: Steroids are hydrophobic molecules which can pass through the cell membrane without the need for a transport protein. Page reference: 27-28

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