Sign In

Essential Biochemistry - Regulation Of Gene Expression And Mutation (Section 1)

1
During the regulation of the lac operon, which process is directly prevented when the repressor binds to the operator?
Answer
(A)
Transcription of the lac genes
2
Which of the following statements about the regulation of the lac operon is correct?
Answer
B
D
3
What is the result of a deletion frame shift mutation?
Answer
(D)
All of the above
4
Which of the following is the inducer molecule for the lac operon?
Answer
(C)
Allolactose
5
Which of the following is NOT a component of the lac operon?
Answer
(D)
Enhancer
6
Which of the following are types of mutations?
Answer
A
B
C
D
7
The lac I gene produces a ___________ that regulates the lac operon.
Answer
(A)
repressor protein
8
A point mutation occurs when ___________.
Answer
(A)
only one base in DNA is altered
9
What is the role of catabolite activator protein (CAP)?
Answer
(C)
It activates transcription when glucose levels are low.
10
The lac operon is a region of DNA in the genome of ___________.
Answer
(A)
E. coli
11
Gene expression is the combined process of the ___________ of a gene into mRNA and its translation into protein.
Answer
(C)
transcription and translation
12
Which of the following can result in a frame shift mutation?
Answer
A
B
13
Which type of mutation results in a stop codon?
Answer
(B)
Nonsense
14
Constitutive genes are genes whose expression is ___________ and they are expressed at a ___________ rate.
Answer
(C)
not regulated, constant
15
When glucose is present, the levels of cAMP ___________, and CAP ___________ bind to the CAP-binding site of the promoter.
Answer
(D)
decrease, cannot
16
Which of the following mutations will lead to premature termination of a polypeptide chain?
Answer
(C)
Nonsense mutation
17
What type of mutation does not change the amino acid sequence?
Answer
(C)
Silent
18
In the absence of lactose, the lac repressor protein ___________ to the operator, thereby ___________ transcription of the structural genes.
Answer
(A)
binds, preventing
19
Which molecule binds to the operator site of the lac operon in the absence of lactose?
Answer
(B)
Repressor protein
20
In positive regulation, a regulatory element or molecule that ___________ the expression of genetic information is considered a(n) ___________.
Answer
(B)
increases, activator
21
Which of the following statements are correct about missense mutations?
Answer
B
C
22
The lac operon structural genes code for enzymes involved in the metabolism of ___________.
Answer
(B)
Lactose
23
In a transition mutation, a ___________ is replaced by another ___________.
Answer
(C)
purine, purine
24
Inducible genes are expressed only when a specific ___________ regulatory substance is present.
Answer
(B)
positive
25
Which of the following is a type of point mutation?
Answer
(C)
Transition
26
What is the primary role of lactose in the lac operon?
Answer
(B)
Inducer
27
Which of the following contribute to the cause of mutations?
Answer
A
B
C
28
What is an operon?
Answer
B
C
D
29
What are the three structural genes found in the lac operon?
Answer
(B)
Z, Y, and A
30
What is an example of an environmental factor that can cause mutations?
Answer
(B)
Sunlight
31
Which of the following events must occur for the lac operon to be fully activated?
Answer
A
B
D
32
What is the general term for a mutation in which a purine is replaced by a pyrimidine, or vice versa?
Answer
(B)
Transversion
33
What is the significance of the lac operon in *E. coli*?
Answer
(B)
It allows *E. coli* to digest lactose.
34
Which type of mutation leads to the premature termination of a polypeptide chain?
Answer
(C)
Nonsense mutation
35
Which of the following is the result of a transition mutation?
Answer
(C)
A purine replaces a purine.
36
What type of mutation is Hb-Hikari?
Answer
(B)
Missense mutation
37
Which operon is responsible for regulating the metabolism of lactose in E. coli?
Answer
(C)
Lac operon
38
What is the consequence of a frame shift mutation?
Answer
A
B
C
39
In the absence of lactose, what happens to the repressor protein?
Answer
(A)
It binds to the operator.
40
Which of the following describes the location of structural genes in an operon?
Answer
(B)
After the operator.
41
In the lac operon, which component is directly responsible for preventing the transcription of the structural genes when lactose is absent?
Answer
(C)
The repressor protein
42
What can cause mutations?
Answer
A
B
C
43
What process is involved in the production of the enzyme beta-galactosidase?
Answer
(A)
Translation
44
What type of mutation results in the conversion of an amino acid codon to a stop codon?
Answer
(C)
Nonsense mutation
45
Which molecule binds to the lac repressor protein to inactivate it?
Answer
(B)
Lactose
46
Which of the following describes the role of the promoter region in a gene?
Answer
(B)
It serves as the start site for transcription.
47
What is a common environmental factor that can cause mutations?
Answer
(B)
UV light
48
What type of mutation results in an acceptable change to the amino acid sequence and protein function?
Answer
(C)
Acceptable missense mutation
49
In which type of regulation is the expression of genetic information increased by the presence of a specific regulatory element?
Answer
(A)
Positive regulation
50
What is the primary function of the CAP (Catabolite Activator Protein) in the lac operon?
Answer
(B)
To enhance the binding of RNA polymerase to the promoter in the absence of glucose and the presence of lactose.