enzymes

Question 1

enzymes

Answer 1

• biological catalysts (a catalyst will provide an alternative reaction pathway with a lower activation energy)
• each enzyme lowers the activation energy of the reaction it catalyses

Question 2

induced fit model

Answer 2

1. before reaction, enzyme active site not completely complementary to substrate/ doesn’t fit substrate
2. active site shape changes as substrate binds and enzyme-substrate complex forms
3. this stresses/ distorts bonds in substrate leading to a reaction

Question 3

temperature - enzyme graph

Answer 3

• optimum temp: around 37
• as the temperature increases, the enzymes and substrate will gain kinetic energy and will move around more quickly so will be more likely to collide successfully and the rate of the reaction with increase
• temp increases pass the optimum, enzymes will denature

Question 4

pH - enzyme graph

Answer 4

• optimum pH - in the body for most enzymes, it’s around pH 7
• there’re some enzymes in the body which have different optimum pH

Question 5

substrate concentration

Answer 5

rate limiting factor = substrate concentration

Question 6

inhibitors

Answer 6

• to inhibit something is to stop or slow something down
• something which will slow down the rate of enzyme controlled reactions

Question 7

competitive inhibitors

Answer 7

• these are of a similar shape to the substrate so can bind to the active site so that the substrate can’t
• these competitive inhibitors will generally come out of the active site again so they are reversible inhibitors

Question 8

non-competitive inhibitors

Answer 8

• these substances will not fit into the active site but they fit into another are on the enzyme called allosteric site
• decreases the rate of reaction