2.1.4 Enzymes

Question 1

what is an example of an intracellular enzyme?

Answer 1

• catalase
• works inside cell
• catalyses breakdown of hydrogen peroxide

Question 2

what’s an example of an extracellular enzyme?

Answer 2

• amylase
• works outside cells in digestive system
• catalyses hydrolysis of starch into maltose

Question 3

what do enzymes do to activation energy?

Answer 3

reduce it

Question 4

what is activation energy?

Answer 4

certain amount of energy needed for a reaction to occur

Question 5

how do enzymes lower activation energy?

Answer 5

• formation of an enzyme substrate complex
• if two substrate molecules need to join, attaching to enzyme holds them together reducing repulsion
• if enzyme is catalysing breakdown reaction, fitting into active site creates a strain in substrate bonds. bonds break up more easily

Question 6

what does the induced fit model say about enzymes?

Answer 6

as substrate binds, active site changes shape slightly to fit substrate more easily

Question 7

what factors affect enzyme activity?

Answer 7

• temp
• ph
• substrate conc
• enzyme conc

Question 8

how does temp affect enzyme activity?

Answer 8

• more kinetic energy so substrates move faster and more collisions so more enzyme substrate complex formed
• if temp goes above certain level, vibration breaks bonds in enzyme, active site changes shape and substrate no longer fits

Question 9

what is the temperature coefficient (Q10)?

Answer 9

how much the rate of reaction changes when temp is raised by 10°C

Question 10

how does ph affect enzyme activity?

Answer 10

• too low or too high ph messes up hydrogen and ionic bonds in tertiary structure
• done by H+ and OH- ions

Question 11

how does enzyme concentration affect enzyme activity?

Answer 11

• more enzyme molecules = more likely for a substrate to collide and bind to form an enzyme substrate complex
• ** if more enzyme than substrates**, all substrates will be used up so increasing conc will then have no effect

Question 12

how does substrate concentration affect enzyme activity?

Answer 12

• higher chance of collision and enzyme substrate complexes forming
• more active sites used up
• after saturation point, all active sites full so increase conc will not increase rate of reaction

Question 13

why is there a need for diff enzymes in diff parts of any process in the body?

Answer 13

• enzymes are specific
• the substrates are different shapes
• active site and substrates are complimentary
• forms an enzyme substrate complex

Question 14

what is a metabolic pathway?

Answer 14

• series of connected metabolic reactions
• product of first reaction takes part in second reaction but each reaction is catalysed by a different enzyme

Question 15

what is product inhibition?

Answer 15

when an enzyme is inhibited by the product of the same reaction they catalyse

Question 16

what is end product inhibition?

Answer 16

when the final product in a metabolic pathway inhibits an enzyme earlier on in the pathway

Question 17

what’s end product inhibition an example of?

Answer 17

• negative feedback
• high level of end product will inhibit enzyme catalysing reaction

Question 18

why is environment being too acidic bad for enzymes?

Answer 18

• very high conc of H+ ions
• alters tertiary structure
• H+ ions affect interactions between amino acids’ R groups
• R groups no longer interact and H/ionic bonds break

Question 19

how can cofactors/coenzymes affect structure of enzyme?

Answer 19

• change tertiary structure
• alter active site
• alter bonds in tertiary structure

Question 20

what are reversible inhibitors?

Answer 20

weak hydrogen/ionic bonds between enzyme and inhibitor, inhibitor can be removed easily

Question 21

what are irreversible inhibitors?

Answer 21

strong bonds between enzyme and inhibitor so inhibitor can’t be removed easily