Enzymes: Enzyme Action
5.1 Enzyme Action
What Are Enzymes?
- Biological catalysts → speed up chemical reactions.
- Made of proteins.
- Not used up or changed in reaction.
How Enzymes Work
- Substrate fits into enzyme’s active site.
- Enzyme-substrate complex forms.
- Reaction occurs → product released.
- Enzyme reused.
- Specificity: one enzyme acts on one substrate only.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course
Lock And Key Hypothesis
- Enzyme’s active site has a complementary shape to substrate.
- “Key” = substrate, “Lock” = enzyme.
- Explains enzyme specificity.
Examples Of Enzymes
| Enzyme | Substrate | Product |
|---|---|---|
| Amylase | Starch | Maltose |
| Maltase | Maltose | Glucose |
| Protease | Protein | Amino acids |
| Lipase | Lipids (fats/oils) | Fatty acids + Glycerol |
Key Points
- Enzymes = essential in respiration, digestion, photosynthesis.
- Work best at optimum temperature and pH.
- Denatured if conditions are extreme → active site shape changes, enzyme stops working.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course