Enzymes

Question 1

What is an Enzyme?

Answer 1

A globular protein that catalysts chemical reaction

(Protein acts as enzymes)

Enzymes speed up chemical reactions & lower activation energy
(faster the molecules move and collide —- faster the rate of reaction)

Question 2

What is a Substrate?

Answer 2

A reactant in an enzyme-catalysed reaction is known as a substrate

Question 3

What is an active site?

Answer 3

place were substrate molecule binds with enzyme —- forms enzyme-substrate complex
(Simply: Place were reactions take place)

A reaction takes place when there is a collision between the substrates and
the active site on the sur€ace o€ the enzyme — resulting in binding —- followed by enzyme-substrate complex (product)
(Process is known as Catalysis)

(enzyme reactions usually occur in aqueous solution e.g cytoplasm)

Question 4

What is Denaturation?

Answer 4

When an enzyme losses its function. because of structural changes

(caused by High temperature or PH)

Question 5

What are Immobilized Enzymes?

Answer 5

An enzyme is fixed on a nonreactive/insoluble material
(basically, enzyme attached to another material)

(Immobilized enzymes provide enzyme resistance to denaturation)

Extra benefit:
1. Immobilized enzymes can also be reused — saves money

(Examples: beads enzymes. used in the milk industry)

Question 6

What two models are used to describe the way enzymes interact with substrates?

Answer 6

Lock and Key Model —- Enzymes acts like the lock and substrate is like the key that fits into the lock

( the enzyme’s active site complements the substrate precisely)

Induced Fit Model —- presence of substrate induces (consumes) enzyme — making it take on a particular shape —- then it carriers out its reaction

(active site will undergo a conformational change when exposed to a substrate to improve binding)

Difference between Lock and Key Model & Induced Fit Model
- In the induced fit model, the active site of the enzyme does not completely fit to the substrate unlike in the lock and key model

Question 7

Factors that affect Enzyme activity?

Answer 7

1. Temperature
   (enzyme denatures at low and high temperatures)
   Optimal Temperature (peak of reaction) — Best rate of reaction
2. PH
   (Enzyme denatures at low and high PH levels)
   Optimal PH (peak of reaction) — Best rate of reaction
3. Substrate Concentration
   (as concentration of substrate increases (add more substrate) — rate of reaction increases until the point of saturation

Point of Saturation — were rate of reaction levels off (cannot go faster)

Question 8

Explain digestion of Lactose

Answer 8

Lactose — sugar found in milk
(Is a combination of glucose & galactose)

Lactose —–breakdown down through hydrolysis
(Lactose + H20 ——> Glucose + Galactose)

Question 9

How is Lactose free milk produced?

Answer 9

By:
1. Adding lactase to milk
(This process can be performed in the laboratory by making
alginate beads (immobilized enzymes) containing lactase and putting them into milk)

( cause lactose concentration to drop & glucose concentration to increase)

Advantage:
1. Many people who cannot drink more than about 250 ml o€ milk per day unless it is lactose-reduced
— symptoms of Lactose intolerant (Diarrhear, nausea & bloating).
Also benefits people are lactose intolerant ( is a source of dairy for lactose-intolerant individuals). Incidence of lactose intolerance is particularly high in Asian, African and Aboriginal populations. Incidence is lower in European populations (due to a mutation that maintains lactase production into adulthood)

2. Acts as a means of increasing sweetness in the absence of artificial sweeteners (monosaccharides are sweeter tasting)

Question 10

Activation Energy & Exothermic reactions & Endothermic reactions

Answer 10

Exothermic reactions (release heat)
--- final energy level is lower than the initial energy level 

Endothermic reactions (absorb heat)
---- final energy level is higher than the initial energy level