Biology 9700 · AS & A Level · Protein synthesis

Protein synthesis — practice question

The enzyme glucose 6-phosphate dehydrogenase (G6PD) is made up of two polypeptide chains that are identical.
(a(i))[3]

Use Fig. 3.1 to complete Table 3.1 by stating: the $V_{max}$ and $K_m$ values for enzymes J and K; the units for $V_{max}$ and $K_m$.

(a(ii))[4]

Using Fig. 3.1 and Table 3.1, describe the effect of the mutation on the activity of G6PD and suggest an explanation for this effect.

(b)[2]

Under some conditions, G6PD may also be present as four identical polypeptide chains instead of two identical polypeptide chains. Explain why both of these forms of G6PD have all four levels of protein structure.

(i)[3]

Use Fig. 3.1 to complete Table 3.1 by stating: - the $V_{\max}$ and the $K_m$ values for enzymes J and K - the units for $V_{\max}$ and $K_m$.

(ii)[4]

Using Fig. 3.1 and Table 3.1, describe the effect of the mutation on the activity of G6PD and suggest an explanation for this effect.

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct unit for $V_{\max}$: $\mu\mathrm{mol\,min^{-1}}$

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