MODULE 2 - ENZYMES

Question 1

what is an intracellular enzyme?

Answer 1

enzymes that work inside the cell

Question 2

what is an extracellular enzyme?

Answer 2

enzymes that work outside the cell

Question 3

what an example of an extracellular enzyme

Answer 3

amylase - breaks down complex carbohydrates (starches) into simpler sugars like maltose

Question 3

what an example of an intracellular enzyme

Answer 3

catalase - rapidly breaks down harmful hydrogen peroxide

Question 4

what 2 things does the lock and key hypothesis suggest happens to aid enzyme action?

Answer 4

• the enzyme holds the substrate so that r/atom groups are close enough to interact
• temporary bonds are formed between substrate r groups and the active site to put strain on the bonds between within the substrate

Question 5

what is enzyme specificity?

Answer 5

each enzyme typically catalyzes only one specific reaction because its unique, protein-determined active site has a shape that is complementary (fits perfectly) to only one specific substrate

Question 6

what does the induced fit hypothesis suggest?

Answer 6

that the substrate changes the shape of the active sight very slightly as it enters. the weak initial reaction does this, changing the enzymes tertiary structure and therefore its active site . binding is then stronger, putting strain on the substrate and weakening its bonds, lowering activation energy

Question 7

state the temperature coefficient

Answer 7

Q10= R2/R1
OR
Q10 = rate of reaction at x+1
——————————–
rate of reaction at x

Question 8

how does increasing the temperature affect enzyme activity?

Answer 8

higher temp = higher kinetic energy = enzymes move faster and more collisions occur –> increased ROR

Question 9

how does increasing the temperature to extremes affect enzyme activity?

Answer 9

breaks the hydrogen bonds within the tertiary structure by giving them so much kinetic energy that the vibrations get to strong, they strain, then break, causing the enzyme to denature.

Question 10

how does pH affect enzyme activity?

Answer 10

excess H+ ions break hydrogen bonds in the enzyme tertiary structure and interfere with ionic forces. this causes denaturing. they can also alter the charges of the active site by clustering around any negative R-groups, therefore interfering with substrate binding

Question 11

how do buffers work?

Answer 11

they maintain a stable pH by neutralising OH- or H+ ions

Question 12

what Is an enzyme inhibitor?

Answer 12

a molecule that binds to an enzyme and blocks activity

Question 13

how does competitive inhibition work?

Answer 13

inhibitors compete with the substrate to bind with the active site - they prevent the substrate from entering, lowering the ROR as less active sites are available

Question 14

how does a non-competitive inhibitor work?

Answer 14

binds to the allosteric site causing the enzymes tertiary structure and therefore active to change so that it is no longer complementary to the substrate
- increased enzyme of substrate conc has no affect
- affect can be permanent or non-permanent

Question 15

what is end product inhibition?

Answer 15

when the product of an enzyme reaction acts as an inhibitor to the enzyme that produced it

Question 16

is end product inhibition competitive?

Answer 16

no

Question 17

why is end product inhibition useful?

Answer 17

prevents wasted resources ad excess products

Question 18

what is end product inhibition an example of?

Answer 18

a negative feedback system

Question 19

what is a coenzyme?

Answer 19

a small, organic, non-protein molecule that helps enzymes function by temporarily binding to them

Question 20

how do coenzymes work?

Answer 20

they bind briefly to the active site just before/simultaneously with the substrate
- they also carry electrons or chemical groups between enzymes (like hydrogen ions) to facilitate biochemical reactions

Question 21

give an example of a coenzymes

Answer 21

NAD

Question 22

what is a prosthetic group of an enzyme?

Answer 22

a non-protein molecule or ion that binds tightly and permanently (often covalently) to an enzyme, becoming an essential part of its structure and function, unlike temporary coenzymes
- enzymes can be inactive without them

Question 23

what are precursor enzymes?

Answer 23

an inactive form of an enzyme that must be modified to become active as it is damaging to the cell it is produced in

Question 24

how are precursor enzymes modified to become active?

Answer 24

a change to their tertiary structure - particularly the active site done by: - adding a cofactor - action of another enzyme - a change in conditions like pH or temp

Question 25

which ion is a cofactor for amylase?

Answer 25

chloride ions