Topic 2.5

Essential idea: Enzymes control the metabolism of the cell.


2.5.U1 Enzymes have an active site to which specific substrates bind

Enzyme structure

2.5.U2 Enzyme catalysis involves molecular motion and the collision of substrates with the active site

Metabolic pathways consist of chains and cycles of enzyme-catalyzed reactions. Enzymes have the ability to bind substrates because of the presence of an active site (i.e., part of an enzyme molecule where a substrate attaches by weak chemical bonds. The active site is usually a pocket or groove on the surface of the enzyme. A substrate is a substance on which an enzyme acts. Enzymes will only bind with a specific substrate or substrates.

Enzyme specificity

2.5.U3 Temperature, pH and substrate concentration affect the rate of activity of enzymes

Effect of temperature on enzyme actitiy

Enzyme specificity

Effect of pH on enzyme activity

Activation energy

Effect of substrate concentration on enzyme activity

Enzyme specificity

2.5.U4 Enzymes can be denatured

Immobilized enzymes

2.5.U5 The use of lactase in the production of lactose-free milk

Immobilized enzymes


2.5.A1 Methods of production of lactose-free milk and its advantages

Making lactose-free milk

Enzyme specificity


2.5.S1 Design experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes

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2.5.S2 Experimental investigation of a factor affecting enzyme activity

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