GCE AQA BIOL - Enzymes
Unit 3.1 Biology and disease
3.1.2 The digestive system provides an interface with the environment. Digestion involves enzymic hydrolysis producing smaller molecules that can be absorbed and assimilated.
Enzymes are biological catalysts that serve to speed up metabolic reactions.
How do enzymes catalyse reactions?
The process of enzyme action In GCE AQA Biology, you need to understand two models of enzyme action:
1. Lock and key model
2. Induced-fit model
Factors affecting enzyme activity You should be able to describe and explain how the following factors affect enzyme activity in GCE AQA Biology:
2. pHSimilarly to temperature, enzyme activity increases up to the optimum pH, peaks at the optimum pH, then decreases thereafter.
Note that a neutral pH is not necessarily the optimum pH - different enzymes have different optimum pHs. Enzymes like stomach proteases have an optimum pH of 1-2, allowing them to function optimally in the acidic stomach environment.
3. Substrate concentration
4. Inhibitors Inhibitors: any molecule that prevents the enzyme from binding to the substrate and catalysing the reaction.GCE AQA Biology requires knowledge of two types of inhibitors:
Graphical representation of the types of inhibition:
We can distinguish between the 2 kinds of inhibitors with the following graph:
That's all for this section!
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Written by Justine | Biology Specialist @ Tuttee
Toole, G., & Toole, S. (2015). Aqa biology A level. Oxford: Oxford University Press.
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