Question 1

A compound known as X-gal is widely used in molecular genetic research. When wild-type (normal)  E. coli is grown on medium containing X-gal, the bacterial colonies turn blue. In contrast, when lacZ mutants are grown on medium containing X-gal, the bacterial colonies remain their normal white color. X-gal is likely to be a compound ________.

Accepted Answer

A)   chemically similar to glucose
B)   chemically similar to galactose
C)   chemically similar to lactose
D)   that cannot be transported into lacZ mutants
E)   that can be transported only into lacA mutantsF) A) and E)
G) A) and D)

Question 2

The product of the lacI gene is ________.

Accepted Answer

A)   an enzyme
B)   a transport protein embedded within the membrane
C)   β-galactosidase
D)   the repressorE) A) and B)
F) None of the above

Question 3

In the first step of their experiments, Jacob and Monod treated E. coli cells with ultraviolet light or X-rays to ________.

Accepted Answer

A)   decrease the rate of gene expression
B)   induce DNA repair enzymes
C)   increase the frequency of mutations in all genes
D)   selectively mutate the lac operon, leaving all other genes unmutatedE) A) and D)
F) C) and D)

Question 4

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator?

Accepted Answer

A)   ubiquitin
B)   inducer
C)   promoter
D)   repressor
E)   corepressorF) A) and C)
G) B) and C)

Question 5

In what general way are regulons regulated?

Accepted Answer

A)   Regulons can be under either positive or negative control.
B)   Regulons are under negative control exclusively.
C)   Regulons are under positive control exclusively.
D)   Global regulation of regulons depends on the regulatory guidance of RNA polymerase II.
E)   Regulons are regulated by feedback translation loops.F) A) and D)
G) None of the above

Question 6

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose)  as a potential food source. Which of the following occurs when lactose enters the cell?

Accepted Answer

A)   The repressor protein attaches to the regulator.
B)   Allolactose binds to the repressor protein.
C)   Allolactose binds to the regulator gene.
D)   The repressor protein and allolactose bind to RNA polymerase.
E)   RNA polymerase attaches to the regulator.F) A) and B)
G) A) and E)

Question 7

When many genes of an organism are globally regulated, those genes are considered as regulon genes. What is the common theme of such genetic regulation?

Accepted Answer

A)   Genes of regulons are silenced by a common repressor.
B)   Genes of regulons are able to transcribe mRNA independent of regulation.
C)   Genes of regulons are much more stable than non-regulon genes.
D)   Genes of regulons are much less stable than non-regulon genes.
E)   Individual genes of regulons are regulated independently of each other.F) C) and E)
G) B) and C)

Question 8

Use this information to answer the question(s)  below.
-If she moves the repressor gene (lacI) , along with its promoter, to a position at some several thousand base pairs away from its normal position, we would expect the ________.

Accepted Answer

A)   repressor will no longer be made
B)   repressor will no longer bind to the operator
C)   repressor will no longer bind to the inducer
D)   lac operon will be expressed continuously
E)   lac operon will function normallyF) C) and D)
G) A) and D)

Question 9

Use this information to answer the question(s)  below.
-If she moves the operator to the far end of the operon, past the transacetylase (lacA)  gene, which of the following would likely occur when the cell is exposed to lactose?

Accepted Answer

A)   The inducer will no longer bind to the repressor.
B)   The repressor will no longer bind to the operator.
C)   The operon will never be transcribed.
D)   The structural genes will be transcribed continuously.
E)   The repressor protein will no longer be produced.F) B) and D)
G) B) and E)

Exam 18: Control of Gene Expression in Bacteria

The product of the lacI gene is ________.

Correct Answer
verified

Correct Answer
verified

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator?

Correct Answer
verified

In what general way are regulons regulated?

Correct Answer
verified

Use this information to answer the question(s) below. -If she moves the repressor gene (lacI) , along with its promoter, to a position at some several thousand base pairs away from its normal position, we would expect the ________.

Correct Answer
verified

Use this information to answer the question(s) below. -If she moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following would likely occur when the cell is exposed to lactose?

Correct Answer
verified

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when lactose enters the cell?

Correct Answer
verified

When many genes of an organism are globally regulated, those genes are considered as regulon genes. What is the common theme of such genetic regulation?

Correct Answer
verified

In the first step of their experiments, Jacob and Monod treated E. coli cells with ultraviolet light or X-rays to ________.

Correct Answer
verified

Exam 18: Control of Gene Expression in Bacteria

The product of the lacI gene is ________.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following, when taken up by a cell, binds to a repressor so that the repressor no longer binds to the operator?

Correct AnswerverifiedShow Answer

In what general way are regulons regulated?

Correct AnswerverifiedShow Answer

Use this information to answer the question(s) below. -If she moves the repressor gene (lacI) , along with its promoter, to a position at some several thousand base pairs away from its normal position, we would expect the ________.

Correct AnswerverifiedShow Answer

Use this information to answer the question(s) below. -If she moves the operator to the far end of the operon, past the transacetylase (lacA) gene, which of the following would likely occur when the cell is exposed to lactose?

Correct AnswerverifiedShow Answer

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when lactose enters the cell?

Correct AnswerverifiedShow Answer

When many genes of an organism are globally regulated, those genes are considered as regulon genes. What is the common theme of such genetic regulation?

Correct AnswerverifiedShow Answer

In the first step of their experiments, Jacob and Monod treated E. coli cells with ultraviolet light or X-rays to ________.

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified