Chemistry 9701 · AS & A Level · Nitrogen compounds

Nitrogen compounds — practice question

Protein molecules are made in the body by joining amino acids together through polymerisation. The structures of three amino acids are shown.
(a(i))[1]

How many distinct tripeptides may be formed using one molecule of each of the amino acids shown?

(a(ii))[2]

Draw the tripeptide ser-gly-val, showing the peptide bonds in displayed form.

(a(iii))[1]

Within the tripeptide, which amino acid has a hydrophobic side chain?

(a(iv))[6]

Polypeptide chains can form bonds that produce proteins' secondary and tertiary structures. Using the tripeptide in (ii), state two types of bonding that may be formed and the groups in the tripeptide that take part in this bonding.

(b(i))[3]

Explain how competitive inhibitors stop enzymes from functioning efficiently.

(b(ii))[3]

Explain how non-competitive inhibitors stop enzymes from functioning efficiently.

(b(iii))[4]

On identical axes, sketch a graph to show the rate of this reaction if a non-competitive inhibitor were present.

Worked solution & mark scheme

This 20-mark question has a full step-by-step worked solution and mark scheme. One marking point: Six possible sequences (e.g. gsv, sgv, gvs, vgs, svg, vsg)

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