This deep dive covers Factors Affecting Enzyme Activity within Enzymes in Digestion for GCSE Biology. Enzyme structure and function, digestive enzymes, factors affecting enzyme activity, lock and key model, and practical investigations It is section 7 of 19 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Factors Affecting Enzyme Activity
Figure: Both temperature and pH follow bell curves with optimum points. Above the optimum, enzymes denature.
1. Temperature
- Low temperature: Enzymes work slowly (less kinetic energy)
- Optimal temperature: Maximum enzyme activity (usually 37°C for human enzymes)
- High temperature: Enzymes denature (active site changes shape permanently)
- Q10 rule: Enzyme activity roughly doubles for every 10°C increase (until denaturation)
2. pH
- Each enzyme has an optimal pH range
- Wrong pH: Changes enzyme shape, reduces activity
- Extreme pH: Permanent denaturation
- Examples: Pepsin (pH 1.5), Amylase (pH 7), Trypsin (pH 8.5)
3. Enzyme Concentration
- More enzymes: More active sites available
- Rate increases until substrate becomes limiting factor
- Plateau reached when all substrate is being used
4. Substrate Concentration
- More substrate: More collisions with active sites
- Rate increases until enzymes become limiting factor
- Maximum rate: The rate levels off when all enzyme active sites are occupied (saturated) — adding more substrate beyond this point has no further effect
Practice questions for Enzymes in Digestion
What are enzymes?
Explain the effect of increasing temperature on enzyme activity.
Quick recall flashcards
What is an enzyme?
A biological catalyst that speeds up chemical reactions by lowering activation energy. Enzymes are proteins with specific 3D shapes.
What does lipase do?
Breaks down lipids (fats) into fatty acids and glycerol. Produced by pancreas, works in small intestine.