Enzymes Flashcards
What is an enzyme?
A biological catalyst that increases the rate of reaction but decreases activation energy without being used up.
What is the Lock and key theory?
a.s and substrate are an exact match
What is the Induced Fit model?
a.s doesn’t exactly match substrate.
A.S slightly changes shape to fit substrate. Forms e.s complex.
Substrate complementary to enzyme.
What factors affect enzyme action?
Temperature, pH, enzyme concentration, substrate concentration.
What happens when the temperature increases to the optimum?
- Increased kinetic energy
- Increased collisions between a.s and substrates
- Increased enzyme substrate complexes formed
- Increased rate of reaction
What happens when temp is too high?
- Enzymes vibrate
- bonds break
- a.s changes shape
- not complementary
- decreased rate of reaction
- enzyme denatured
What happens above or below the optimum pH?
- The H+ ions in acids and OH- ions in alkalis affect H bonds and ionic bonds in tertiary structure.
- a.s changes shape
- no longer complementary
- decreased rate of reaction
- enzyme denatured
What happens as the number of enzymes increases?
- Increased number of a.s available
- Increased number of e.s complexes
- Increased rate of reaction
- Substrate concentration becomes limiting
What happens as substrate concentration increases?
- More substrates so more collisions
- increased e.s complexes
- increased rate of reaction
- enzyme concentration becomes limiting as no free active sites.
What is an inhibitor?
A molecule that binds to an enzyme and stops it from working as no e.s complexes can be formed.
What is a competitive inhibitor?
Similar shape to substrate
binds with a.s of enzyme
decreases ror as less e.s complexes form.
How can competitive inhibition be overcome?
Increase sub concn as there are more collisions
What is non competitive inhibition?
- Binds away from a.s
- a.s changes shape
- substrate can’t bind
- no e.s complexes form.
