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Question 1
The diagram below shows the amino acids leucine, proline and glutamic acid. |
a) | Give the IUPAC name of leucine.
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b) | Draw the zwitterion of proline.
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c) | Draw the structure of the product formed when glutamic acid is dissolved in an acidic solution.
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d) | Draw the structure of the tripeptide leucine-proline-leucine, formed from one molecule of proline and two molecules of leucine.
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Question 2
This question is about proteins and DNA. |
A bond can form between two polypeptide chains that both contain the amino acid cysteine. The structure of cysteine is shown below. |
a) | Complete the diagram below to show the bond that forms between two molecules of cysteine.
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b) | The bond in part a) influences the 3D structure of a protein. Name this type of protein structure.
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c) | The diagram below shows a fragment of a DNA double helix. Complete the diagram to show the correct sequence of complementary base pairs in strand 2.
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d) | The diagram below shows an incomplete molecule of 2-deoxyribose. Complete the diagram to show the structure and position of a base and a phosphate group. Use 'B' to represent the structure of a base.
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Question 3
The diagram below shows the structure of the amino acid alanine. |
a) | Outline the mechanism for the formation of alanine from CH3CHClCOOH and ammonia.
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b) | Draw the structure of the zwitterion formed by alanine.
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c) | Draw the structure of the product formed when alanine reacts with CH3OH in the presence of concentrated H2SO4.
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Question 4
The diagram below shows the structure of the amino acid aspartic acid. |
a) | Draw the structure of the product formed when aspartic acid is reacted with HCl.
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b) | Draw the structure of the product formed when aspartic acid is reacted with excess CH3OH and H2SO4.
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c) | Draw the structure of aspartic acid when it is dissolved in a solution with a high pH.
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