Biology 9700 · AS & A Level · Protein synthesis

Protein synthesis — practice question

A range of microorganisms are able to break down cellulose with a set of enzymes known as cellulases. The disaccharide formed as cellulose is digested is cellobiose. The cellulase called $\beta$-glucosidase finishes cellulose digestion by hydrolysing one cellobiose molecule to make two $\beta$-glucose molecules.
(a)[2]

Use the space provided to draw the ring structure of one $\beta$-glucose molecule.

(b)

$\beta$-glucosidase was obtained from two different bacteria, Agrobacterium tumefaciens and Thermotoga maritima. Fig. 4.1 presents the findings of an investigation into how temperature, from $0\,^{\circ}\text{C}$ to $100\,^{\circ}\text{C}$, affects the activity of each enzyme. L is the lowest temperature at which activity of each enzyme was observed. H is the highest temperature at which activity of each enzyme was observed.

(b(i))[4]

Using Fig. 4.1, describe how the results for enzymes A and T differ.

(b(ii))[4]

Both enzyme A and enzyme T act on cellobiose. Their primary structure is similar, though not exactly the same. Suggest how similarities and differences in the primary structure of the two enzymes could help to account for the results obtained in the investigation.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Accurate hexose ring structure with oxygen inside the ring

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