Presentation Transcript
Biology :Biology Enzymes
Enzymes :Enzymes Protein molecules without which life could not exist
Catalysts - speed up reactions but are not used up
Energy of activation – enzymes lower the energy needed for molecules to react with one another.
Enzymes :Substrates - The reactants in the reaction
Active site—the part of the enzyme into which the substrate molecule fits.
Induced fit—the enzyme undergoes a slight change in shape in order to fit with the substrate(s). Fit together in same way as lock and key Enzymes
Figure 6.15 The catalytic cycle of an enzyme :Figure 6.15 The catalytic cycle of an enzyme
Enzymes :Enzymes Rate of reaction - the amount of product per unit of time (ex. 6,000 in 6 minutes = rate of 1000 per minute)
Factors affecting the rate include:
1. Substrate concentration
2. Enzyme concentration
3. Temperature—temperatures over 50-60oC denature
proteins by causing them to unwind. Cooler temperatures slow down the reaction. Why?
4. pH—most enzymes are active only over a narrow range
of pH
Enzymes :Control of Enzyme Activity
Coenzymes – additional molecules needed for enzymes to work
Enzyme Inhibition—occurs when an active enzyme is prevented from combining with its substrate.
Competitive – blocks site
Noncompetitive – changes shape Enzymes