WORKBOOK EXERCISE
NURSING PROGRAM
CHAPTER 5
ENZYME
Question 1-6 (related to assignment)
1
Which of the following description about enzyme is false?
A
B
C
D
2
Enzyme is a protein
Enzyme will change the free energy
Enzyme accelerates chemical reaction
Enzyme will not consumed by the reaction
Choose the incorrect statement about the activation energy?
A
B
C
D
3
It is the initial energy that absorbed by the reactant
Energy released from spontaneous reaction
Enzyme lower the activation energy to speed up reaction
Energy absorbed by reactant to reach transition state even at moderate
temperature
Figure 1 shows mechanism of enzyme’s action.
N
P
L
M
Choose the correct labels for the above diagram.
A
L
Enzyme
M
Substrate
B
Substrate
Enzyme
C
Enzyme
Inhibitor
D
Enzyme
Inhibitor
N
Enzyme-substrate
complex
Enzyme-substrate
complex
Enzyme-substrate
complex
Enzyme-substrate
complex
P
Products
Products
Substrate
Products
4
Which of the followings is not true about active site?
A
B
C
D
5
6
It is flexible and can change shape
It is made of a few of enzyme’s amino acid
It is exactly complement with shape of substrate
Enzyme specificity is depends on complimentary fit between shape of active
site and substrate
Arrange the correct sequence of enzyme catalysis.
I
II
III
IV
V
Substrates are converted into products
Substrates binds to the active site of enzyme
Active site lowers the activation energy that speeds up the reaction
Substrates held in the active site by hydrogen bonds and ionic bonds
Products are released, and active sites are available for new substrates
A
B
C
D
II, I, III, IV, V
V, III, II, IV, I
III, IV, V, II, I
II, IV, III, I, V
Figure below shows the effect of pH on activity of enzyme pepsin.
Figure
Which of the following statements is not true about the above figure?
A
B
C
D
7
Optimum pH of pepsin is 2
Pepsin is inactive when pH is more than 2
Maximum rate of pepsin reaction of pepsin is achieved at pH 3.5
Active sites of pepsin cannot bind with substrate at pH 2
Which of the followings is an example of endergonic reaction?
A
B
C
D
Photosynthesis
Respiration
Hydrolysis of ATP
Break down of glucose
8
Which of the following statements is true about the exergonic reaction?
A
B
C
D
9
Reaction absorbs free energy from surroundings
Products contain more energy than reactants
Reaction involves in synthesis of molecules
Reaction is nonspontaneous
The figure below shows the energy level during a non-enzyme catalysed and enzymecatalysed reaction.
Which of the label in the figure represents the activation energy for the enzymecatalysed reaction?
10
All of the following are examples of coenzymes except
A
B
C
D
11
CoA
ATP
NAD+
Haem
Binding of chloride ions (Cl-) to salivary amylase enable amylose to occupy the
enzyme’s active site. Cl- is an example of
A
B
C
D
coenzyme
inorganic ions
allosteric inhibitor
prosthetic group
12
Which of the following is not true about competitive inhibitors?
A
B
C
D
13
_______________ occurs when the end product of a metabolic pathway binds to the
enzyme of the early in the pathway in order to stop the reaction.
A
B
C
D
14
Reversible inhibition
Irreversible inhibition
Feedback inhibition
Allosteric activation
The addition of a competitive inhibitor slows down enzyme catalysed reaction. Which
of the following will increase the rate of the reaction?
A
B
C
D
15
Inhibitors resemble the substrates
Inhibitors bind with the active site of enzymes
Inhibition can be prevented by adding more enzymes
No products generated if inhibitors bind at the active sites
Reduce the concentration of coenzyme
Reduce the temperature of the reaction
Increase the concentration of substrates
Increase the pH of solution
The figure below shows a reaction catalysed by an enzyme.
The enzyme shown in above reaction is classified as
A
B
C
D
lyase
hydrolase
isomerase
transferase
16
The figure below shows a reaction catalysed by enzyme Glucose isomerase.
Glucose isomerase is classified as
A
B
C
D
17
lyases
hydrolases
isomerases
transferases
The figure below shows a reaction catalysed by an enzyme.
The enzyme shown in above reaction is classified as
A
B
C
D
18
lyases
hydrolases
isomerases
transferases
The figure below shows a reaction catalysed by enzyme.
The enzyme shown in above reaction is classified as
A
B
C
D
ligases
hydrolases
isomerases
transferases
19
The figure below shows a reaction catalysed by enzyme.
The enzyme shown in above reaction is classified as
A
B
C
D
lyases
hydrolases
isomerases
oxidoreductases
STRUCTURE QUESTION
1
Figure below shows a type of chemical reaction.
(a)
Identify type of chemical reaction shown in the figure.
[1 mark]
_______________________________________________________________
(b)
Give example of reaction involved with the above chemical reaction.
[1 mark]
_______________________________________________________________
(c)
Give three (3) differences between the chemical reaction shown in the above
figure with chemical reaction in respiration.
[3 marks]
Chemical reaction of the figure
2
respiration
Compare CoA and Haem.
[3 marks]
CoA
Haem
Similarity
Differences
3
The figure below shows an enzyme catalysed reaction in the presence of inhibitor.
(a)
Identify P, substrate Q and inhibitor R.
[3 marks]
(i) P: __________________________________________________________
(ii) Q: _________________________________________________________
(iii) Inhibitor R (competitive/non-competitive): ________________________
(b)
(i)
Give reason for your answer in (a)(iii).
[1 mark]
_______________________________________________________________
(ii)
What would happen when inhibitor R binds to the active site of
enzyme succinate dehydrogenase?
[2 mark]
_______________________________________________________________
_______________________________________________________________
(c)
Classify the enzyme shown in the figure according to International United of
Biochemistry (IUB).
[1 mark]
______________________________________________________________
(d)
Suggest one way to overcome the inhibition by inhibitor R.
[1 mark]
_______________________________________________________________
4
Figure below shows three different curves of enzyme activity in the presence of
inhibitor H, and I.
Normal enzyme
Inhibitor H
Inhibitor I
(a)
Identify
(i)
Inhibitor H: _______________________________________
(ii)
Inhibitor I: ________________________________________
[2 marks]
(b)
Why is the rate of reaction for enzyme in the presence of inhibitor I is lower
than in the presence of of inhibitor H?
[1 mark]
_______________________________________________________________
(c)
Differentiate inhibition by inhibitor H and I.
[3 marks]
Inhibition by Inhibitor H
Inhibition by Inhibitor I
5
The figure below shows the pathway of threonine converted into isoleucine which is
regulated by feedback inhibition.
(a)
Identify enzyme R.
[1 mark]
Enzyme R: ___________________________________________________________
(b)
Identify the inhibitor of the above feedback inhibition.
[1 mark]
_____________________________________________________________________
(c)
Explain how feedback inhibition prevents excessive production of isoleucine.
[2 marks]
_____________________________________________________________________
_____________________________________________________________________