3.2. Factors that affect enzyme action
A subsection of Biology, 9700, through 3. Enzymes
Listing 10 of 202 questions
High fructose corn syrup, made from maize, can be used as a replacement for sucrose to sweeten food and drink products. Commercial production of high fructose corn syrup involves the enzyme glucose isomerase, extracted from bacteria. Fructose and sucrose are both sugars. State two structural differences between fructose and sucrose. The glucose isomerase used in the production of high fructose corn syrup is extracted from a strain of a bacterium, Thermus thermophilus, which is found in hot springs. The enzyme has an optimum temperature of 95 °C. Suggest and explain the advantages of using glucose isomerase from T. thermophilus to produce high fructose corn syrup, rather than using glucose isomerase that has an optimum temperature of 37 °C. The commercial production of high fructose corn syrup uses immobilised glucose isomerase. shows the effect of pH on the activity of immobilised glucose isomerase compared to glucose isomerase free in solution. percentage activity pH glucose isomerase free in solution (free enzyme) immobilised glucose isomerase (immobilised enzyme) With reference to , describe the differences shown between the immobilised enzyme and the free enzyme as pH changes. The amino acid sequence of the enzyme glucose isomerase has been determined. The first five amino acids of this sequence are shown in Table 3.1. Table 3.2 (on page 11) shows the genetic code (mRNA codons). A student was asked to use Table 3.2 to work out an mRNA nucleotide sequence that would correspond to the first five amino acids of glucose isomerase. The student’s sequence is shown in Table 3.1. Table 3.1 amino acid sequence met tyr glu pro lys student’s nucleotide sequence AUG UAU GAC CCU UGU correct = 3 incorrect = 7 Complete Table 3.1 using a 3 or a 7 to indicate whether the student has used Table 3.2 correctly to identify the codons for each amino acid in the nucleotide sequence. Discuss, with reasons, how an mRNA nucleotide sequence worked out to correspond to the first five amino acids using Table 3.2 may not be the same as the mRNA nucleotide sequence for those amino acids present in the bacterial cell.
9700_w16_qp_22
THEORY
2016
Paper 2, Variant 2
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Amylase is an enzyme that catalyses the hydrolysis of starch into reducing sugars. A student carried out an experiment to investigate the hydrolysis of starch using immobilised amylase. is a diagram of the apparatus that was used in the investigation. starch solution immobilised amylase in alginate beads beaker for collecting product tap tap The alginate beads were all the same size. Both taps were opened to allow the starch solution to flow down the column and for the product to be collected. The product was tested for the presence of reducing sugar and starch. The results of the investigation showed that the product collected in the beaker contained reducing sugar and starch. With reference to , describe a method that would allow the student to use the immobilised amylase to collect a product that contains only reducing sugar. One standardised variable in the investigation is the size of the alginate beads. Suggest one reason why using larger or smaller alginate beads in the column would affect the results obtained.
9700_w21_qp_22
THEORY
2021
Paper 2, Variant 2
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Questions Discovered
202