Enzymes Flashcards
1
Q
Why are enzymes specific in shape?
A
Due to specific folding/bonding in the tertiary structure of proteins
2
Q
What effect do enzymes have on activation energy?
A
They lower it (act as a catalyst)
3
Q
What is the lock and key model?
A
- suggests active site is fixed
- substrate collides/attaches due to random collisions + ES complex formed
- charged groups within active site distort substrate (lower activation energy)
- products released and enzyme ready to be reused
4
Q
What is the induced fit model?
A
- active site induced to fit substrate
- when ES complex occurs, moulding around substrate puts strain on bonds (lowers activation energy)
- products removed + enzyme ready to be reused
- accepted model
5
Q
How does temperature affect rate of reaction?
A
- Too high = enzymes denature (hydrogen/ionic bonds broken) and active site changes shape = no ES complexes formed
- Too low = low kinetic energy = less successful collisions
6
Q
How does pH affect rate of reaction?
A
- Too low/high pH interferes with charges in amino acids in active site = breaks bonds in tertiary structure = enzyme denatured (ES complexes can’t form)
7
Q
How does substrate/enzyme concentration affect rate of reaction?
A
- Too low conc = fewer collisions
- Low enzyme conc = active sites become saturated with substrate = unable to work faster
- Low substrate conc = empty active sites = unable to work faster
8
Q
How do competitive inhibitors affect rate of reaction?
A
- Similar shaped molecules which act as substrates
- prevent substrate from binding + reaction occurring
9
Q
How does increasing substrate concentration affect competitive inhibitors?
A
- out-competes them, knocking them out of active site
- rate of reaction returns back to normal
10
Q
How do non-competitive inhibitors affect rate of reaction?
A
- bind to enzyme away from active site (allosteric site)
- causes active site to change shape
- substrate can no longer bind
11
Q
How does increasing substrate concentration affect non-competitive inhibitors?
A
- No difference as, once affected, substrate can no longer bind to active site
