3. Enzymes

Question 1

Enzymes

Answer 1

enzymes are globular proteins that catalyse reactions inside cells (intracellular enzymes) or are secreted to catalyse reactions outside cells (extracellular enzymes)

Question 2

mode of action of enzymes

Answer 2

active site, enzyme–substrate complex, lowering of activation energy and enzyme specificity, including the lock-and-key hypothesis and the induced-fit hypothesis

Question 2

investigate the progress of enzyme-catalysed reactions by measuring

Answer 2

rates of formation of products using catalase and rates of disappearance of substrate using amylase

Question 3

use of a colorimeter

Answer 3

for measuring the progress of enzyme-catalysed reactions that involve colour changes

Question 4

effect on the rate of enzyme-catalysed reactions: temperature and ph using buffer solutions

Question 4

explain Vmax and Km

Answer 4

the maximum rate of reaction (Vmax) is used to derive the Michaelis–Menten constant (Km), which is used to compare the affinity of different enzymes for their substrates.

Question 5

effect on the rate of enzyme-catalysed reactions: enzyme conc, substrate conc, inhibitor conc

Question 6

effects of reversible inhibitors, both competitive and non-competitive, on enzyme activity

Question 7

investigate the difference in activity between an enzyme immobilised in alginate and the same enzyme free in solution,

state the advantages of using immobilised enzymes