Chemistry 9701 · AS & A Level · Nitrogen compounds

Nitrogen compounds — practice question

Protein molecules are produced in the body when amino acids are polymerised. The structures of three amino acids are provided: glycine (gly), serine (ser) and valine (val).
(a(i))[1]

How many different tripeptides may be formed using one molecule of each amino acid shown?

(a(ii))

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 give proteins their secondary and tertiary structures. Using the tripeptide in (ii), state two types of bonding that may be formed and the groups in the tripeptide involved in this bonding.

(b(i))[3]

Explain how competitive inhibitors stop enzymes working efficiently.

(b(ii))[3]

Explain how non-competitive inhibitors stop enzymes working efficiently.

(b(iii))[4]

The graph shows the rate of an enzyme-catalysed reaction against the substrate concentration when no inhibitor is present. On the same axes, sketch a graph showing the rate of this reaction if a non-competitive inhibitor were present.

(c(iii))[4]

The graph shows the rate of an enzyme-catalysed reaction against the substrate concentration when no inhibitor is present. On the same axes, sketch a graph showing the rate of this reaction if a non-competitive inhibitor were present.

Worked solution & mark scheme

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