Biology 9700 · AS & A Level · Carbohydrates and lipids

Carbohydrates and lipids — practice question

Sucrose phosphorylase is an enzyme present in some bacterial species. One role of this enzyme is to make compounds that protect the cell against damaging osmotic changes in the external environment. Fig. 5.1 illustrates the reversible reaction occurring inside the bacterial cell.
(a)[1]

Name the reducing sugar X shown in Fig. 5.1.

(b)[2]

Without sucrose phosphorylase acting as a catalyst, the reaction in Fig. 5.1 would be too slow to occur for the bacterial cell to operate efficiently. Explain why the reaction shown in Fig. 5.1 happens much more rapidly when the enzyme is present.

(c)

An enzyme catalysing a reaction of commercial value must be tested to check whether it is suitable for industrial use. For instance, immobilised enzymes can be used because they last longer than the enzyme free in solution; many industrial reactions are carried out at higher temperatures to reduce contamination of products by microorganisms. Fig. 5.2 presents the findings of an investigation comparing sucrose phosphorylase free in solution (free enzyme) with immobilised sucrose phosphorylase (immobilised enzyme) at different $\text{pH}$. Fig. 5.3 shows the activity of the free enzyme and immobilised enzyme at different temperatures.

(d)[4]

Using the results in Fig. 5.2 and Fig. 5.3, discuss whether the free or immobilised sucrose phosphorylase enzyme is better suited to industrial reactions.

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