1.4 Enzymes Flashcards
What is a catalyst?
Substance that speeds up a reaction without changing the substances produced or being changed itself
What are enzymes?
Biological catalysts
Proteins that have a a specific shape
Each enzyme will only catalyse a specific reaction or group of reactions
Describe the lock and key hypothesis.
States that the active site of an enzyme precisely fits a specific substrate only
Describe the induced fit hypothesis.
States that the active site of an enzyme will undergo a conformational change when binding a substrate to improve the fit
Explain the effect of increasing temperature on rate of an enzyme catalysed reaction.
Higher kinetic energy so more enzyme-substrate complexes formed
At very high temperatures the rate decreases due to denaturation
Because of bond changes in the enzyme altering the active site
So substrate no longer fits active site
Use your knowledge of the tertiary structure of enzymes to explain how a non-competitive inhibitor could reduce the rate of an enzyme-controlled reaction.
Inhibitor is a different shape to substrate
This means it binds at a position other than the active site
This alters the shape of the active site
Substrate won’t be able to bind
Describe and explain how pH affects the rate of enzyme controlled reactions.
Ionic bonds that hold tertiary structure break
Active site distorts and substrate no longer binds to active site
Charge on amino acids in active site affected
So fewer enzyme-substrate complexes form
Competitive and non competitive inhibitors affect the activity of enzymes. Explain how.
Competitive inhibitor:
1. Inhibitor similar in shape to substrate
2. Competed for active site
3.Less substrate attaches
Non-competitive inhibitor:
4. Inhibitor differs in shape to substrate
5. Binds at a position other than active site
6. Alters active site so substrate cannot bind
