2.5

Question 1

Define enzyme

Answer 1

a group of proteins acting as biological catalysts to speed up reactions

Question 2

Define active site

Answer 2

A specifically shaped region on an enzyme’s surface to which a substrate binds

Question 3

Define substrate

Answer 3

the substance in which the enzyme acts

Question 4

Outline that enzyme activity involves molecular motion & the collision of substrates w/ the active site

Answer 4

A specific substrate molecule collides w/ an enzyme’s active site & binds to it

Whilst in the active site, the substrates are altered into different products

Products are released on the active site, so enzyme can be reused

Question 5

Explain what is meant by enzyme substrate collisions & enzyme-substrate specificity:

Answer 5

Collisions:
enzymes & substrates dissolved in water = free movement
collision b/w them occur due to random movement, and they must collide w/ the active site in the right orientation for successful collision

Specificity:
most enzymes only bind to 1 type of substrate
this is because the shape of the active site is specific & complementary to the shape of the substrate

Question 6

Enzyme models:

Lock & Key model

Answer 6

Active site represents lock, substrate represents key
The A.S is specific & complementary to the substrate shape, fitting like a key in a lock
Products are released from A.S so enzyme can be reused

Question 7

Enzyme models:

Induced-Fit model

Answer 7

Substrate has similar shape to A.S
When substrate binds to A.S it interacts w/ R-groups of amino acids & induces a shape change to the A.S —> substrate fits better
Help weaken bonds in substrate to catalyse the reaction

Question 8

Describe & explain the effect of temp, pH, and substrate concentration on enzyme activity

Answer 8

SEE 2.5 BOOKLET

Temperature
• Increases enzyme activity (more kinetic energy = more collisions)
• Enzyme activity peaks at an optimal temperature
• Higher temperatures decrease activity (causes denaturation)

pH
• Enzyme activity is highest at an optimal pH range
• Activity decreases outside of this range (due to denaturation)

Substrate Concentration
• Increases enzyme activity (more particles = more collisions)
• At a certain point, activity plateaus (saturation of active sites)

Question 9

What are the methods of producing lactose free milk and its advantage?

Answer 9

Lactase is added to milk, which hydrolyse the lactose into galactose + glucose

Galactose + glucose are sweeter than lactose
They’re mole soluble—-> smooth texture
Good source of protein
No side effects for lactose-intolerant people
Doesn’t crystallise in ice cream

Question 10

List some advantages of using immobilised enzymes in industry:

Answer 10

• immobilised enzymes can be easily retrieved from reactions & used again—> saves money
• immobilised enzymes can be removed, they don’t contain the products of a reaction—> enables reactions to be stopped at ideal times
• immobilisation increases enzyme stability to temperature & pH changes —> reduces denaturation rates
• substrates can be exposed to higher concentrations of immobilised enzymes compared to dissolved enzymes
• –> speeds up reaction rates & therefore production time