7

1. Which of the following is absent in an operon?

A. o

perator
B. p

romoter
C. intron

D. both operator and promoter

E. b
oth promoter and intron

2. Identify the allosteric protein.

A. o

perator
B. r epressor

C. promoter

D. β-galactosidase

E. p ermease

3. Which of the following bond creates the linkage between glucose and galactose?

A. a

glycoside bind.
B. T

he linkage is through β-1, 4 bond.
C. It can be broken by β-galactosidase.

D. It is a covalent bond.

E. A
ll of the choices are correct.

4. Which of the following statements is true about a lac operon with the following genotype?
I- Oc Z+ Y-
I- O+ Z- Y-

A. A

repressor protein will be constitutively produced.
B. β

-galactosidase will be constitutively produced.
C. A cis-dominant mutation is present.

D. Permease will be constitutively produced.

E. B
oth A. a repressor protein will be constitutively produced and C. a cis-dominant mutation is
present are correct.


5. Which of the following plasmids could be used to restore inducible regulation of β-galatosidase in
this mutant: I+ Oc Z-Y+ A+?

A. I + Oc Z- Y+ A+

B. I + Oc Z- Y- A-

C. I- O+ Z+ Y+ A+

D. I-Oc Z+ Y+ A+

E. B oth A. I+ Oc Z- Y+ A+ and B. I+ Oc Z- Y- A- are correct.

6. Which of the following organisms would produce functional lac products in the presence of
IPTG?

A. I s Oc Z- Y+ A+

B. I s Oc Z- Y- A-

C. I+ O+ Z+ Y+ A+

D. I-Oc Z+ Y+ A+

E. B oth Is Oc Z- Y+ A+ and Is Oc Z- Y+ A+ are correct

7. Which of the following statements is true about a lac operon with this genotype?
I-d O+ Z+ Y- A-

A. T

he operon is repressible.
B. T

he operon is nonrepressible.
C. The mutation is cis-dominant.

D. The operon is uninducible.

E. N
one of the choices is correct.

8. Which of the following techniques is most useful in determining if RNA polymerase has initiated
transcription from the lac DNA template?

A. S

outhern analysis
B. D

NA fingerprinting
C. run-off transcription assay

D. DNA sequencing

E. R
ACE


9. In an in vitro transcription assay to detect the level of transcription from a lac operon, one of the
RNA precursors was tagged with a fluorescent label on the β-phosphate. Which of the following is
a likely outcome if transcription occurred?

A. T

he level of fluorescence would increase along the new RNA strand.
B. E

ach RNA would have a fluorescent tag on every other nucleotide.
C. The level of fluorescence would be very high in the assay buffer.

D. No fluorescence would be detected in the buffer at the end of the assay.

E. A
ll of the choices are possible.

10. The identity of the following molecule is

A. g

alactose.
B. l actose.

C. glucose.

D. cAMP.

E. h eparin.

11. Which of the following is most likely to occur if the level of glucose is low in a bacterial cell?

A. C

yclic-AMP levels will be depressed.
AP will assist in stimulating transcription of the lac operon.
B. C

C. CRP activity will be inhibited.

D. Both Cyclic-AMP levels will be depressed and CRP activity will be inhibited are correct.

E. N
one of the choices is correct.

12. Which of the following is true about the action of CAP at the lac promoter?

A. C

AP monomer binds directly to the promoter stimulating polymerase to bind.
B. C

AP-AMP blocks recruitment of polymerase to the promoter.
C. CAP blocks the αCTD of RNA polymerase.

D. Binding of the CAP-cAMP to the lac activator-binding site recruits RNA polymerase.

E. C
AP monomer binds directly to the promoter stimulating polymerase to bind and CAP blocks
the αCTD of RNA polymerase are correct.


13. Which of the following is true about the regulation of the trp operon?

A. A

n aporepressor is involved.
B. A

corepressor is involved.
C. Attenuation is one of the mechanism of control.

D. Negative control is involved.

E. A
ll of the choices are true.

14. Which of the following is an example of an allosteric interaction?

A. a

llolactose binding to a repressor
B. a

n aptamer binding to a riboswitch
C. polymerase binding to the promoter

D. repressor binding to the operator

E. b
oth A. allolactose binding to a repressor and B. an aptamer binding to a riboswitch

15. In the process of creating a trp operon mutant, the region for the riboswitch was accidentally
deleted. Which of the following would be a likely observation in the transcription assays?

A. R

NA polymerase cannot bind to the promoter.
B. T

he operon is permanently inhibited.
C. Attenuation would be impaired.

D. Termination would be triggered .

E. T
he chance of an aptamer binding to the mRNA 5′-UTR increases.

16. Which of the following would be effective in blocking transcription from the lac operon in the
presence of permease?

A. a

ntibody to RNA polymerase
B. a

ntibody to the repressor protein
C. mutation in the operator

D. an antibody to β-galactosidase

E. b
oth antibody to RNA polymerase and mutation in the operator

17. ________ __________is the enzyme needed to bring lactose into the bacterial cell.

________________________________________

18. β-galactosidase cleaves the disaccharide lactose into __________ and ____________.

________________________________________

19. In the presence of glucose the lac operon is kept inactive by _________ _________.

________________________________________

20. The ara operon is controlled by the _____________ protein.

________________________________________

21. ________ is a term used to describe a mechanism in which a protein controls it's own regulation.

________________________________________

22. Regions of the 5′-UTRs of mRNAs that alter their structures to control gene expression are called
_____________________.

________________________________________

23. If an operon is under negative control it means that the operon is never operational.

True False

24. In the absence of glucose there will be a rapid accumulation of lactose in the following mutant:
I- Oc Z+ Y-
I- O+ Z+ Y-

True False

25. The following is an example of a cis-dominant mutation:
I-d O+ Z+ Y+ A-

True False

26. Recent experimental evidence has shown that only one operator sequence is needed for maximal
expression.

True False

27. One hypothesis explaining the mechanism of repression of the lac operon states that the
repressor binds to the operator and blocks access by the polymerase to the adjacent promoter.

True False

28. cAMP level is increased by the presence of high levels of glucose.

True False

29. Arabinose can derepress the ara operon by causing AraC to loosen its attachment to araO2 and
to bind to araI2 instead.

True False

30. Attenuation causes the length of the RNA molecules to be significantly extended.

True False

 7 Key

1. Which of the following is absent in an operon?

A. operator

B. promoter

C. intron

D. both operator and promoter

E. both promoter and intron

Blooms Level: 2. Understand

Section: 07.01
Weaver - Chapter 07 #1


2. Identify the allosteric protein.

A. operator

B. repressor

C. promoter

D. β-galactosidase

E. permease

Blooms Level: 2. Understand

Section: 07.01
Weaver - Chapter 07 #2


3. Which of the following bond creates the linkage between glucose and galactose?

A. a glycoside bind.

B. The linkage is through β-1, 4 bond.

C. It can be broken by β-galactosidase.

D. It is a covalent bond.

E. All of the choices are correct.

Blooms Level: 5. Evaluate

Section: 07.01
Weaver - Chapter 07 #3



4. Which of the following statements is true about a lac operon with the following genotype?
I- Oc Z+ Y-
I- O+ Z- Y-

A. A repressor protein will be constitutively produced.

B. β-galactosidase will be constitutively produced.

C. A cis-dominant mutation is present.

D. Permease will be constitutively produced.

E. Both A. a repressor protein will be constitutively produced and C. a cis-dominant mutation

is present are correct.

Blooms Level: 5. Evaluate

Section: 07.01
Weaver - Chapter 07 #4


5. Which of the following plasmids could be used to restore inducible regulation of β-galatosidase
in this mutant: I+ Oc Z-Y+ A+?

A. I+ Oc Z- Y+ A+

B. I+ Oc Z- Y- A-

C. I- O+ Z+ Y+ A+

D. I-Oc Z+ Y+ A+

E. Both A. I+ Oc Z- Y+ A+ and B. I+ Oc Z- Y- A- are correct.

Blooms Level: 5. Evaluate

Section: 07.01
Weaver - Chapter 07 #5


6. Which of the following organisms would produce functional lac products in the presence of
IPTG?

A. Is Oc Z- Y+ A+

B. Is Oc Z- Y- A-

C. I+ O+ Z+ Y+ A+

D. I-Oc Z+ Y+ A+

E. Both Is Oc Z- Y+ A+ and Is Oc Z- Y+ A+ are correct

Blooms Level: 5. Evaluate

Section: 07.01
Weaver - Chapter 07 #6



7. Which of the following statements is true about a lac operon with this genotype?
I-d O+ Z+ Y- A-

A. The operon is repressible.

B. The operon is nonrepressible.

C. The mutation is cis-dominant.

D. The operon is uninducible.

E. None of the choices is correct.

Blooms Level: 4. Analyze

Section: 07.01
Weaver - Chapter 07 #7


8. Which of the following techniques is most useful in determining if RNA polymerase has
initiated transcription from the lac DNA template?

A. Southern analysis

B. DNA fingerprinting

C. run-off transcription assay

D. DNA sequencing

E. RACE

Blooms Level: 3. Apply

Section: 07.01
Weaver - Chapter 07 #8


9. In an in vitro transcription assay to detect the level of transcription from a lac operon, one of
the RNA precursors was tagged with a fluorescent label on the β-phosphate. Which of the
following is a likely outcome if transcription occurred?

A. The level of fluorescence would increase along the new RNA strand.

B. Each RNA would have a fluorescent tag on every other nucleotide.

C. The level of fluorescence would be very high in the assay buffer.

D. No fluorescence would be detected in the buffer at the end of the assay.

E. All of the choices are possible.

Blooms Level: 5. Evaluate

Section: 07.01
Weaver - Chapter 07 #9



10. The identity of the following molecule is

A. galactose.

B. lactose.

C. glucose.

D. cAMP.

E. heparin.

Blooms Level: 1. Remember

Figure 07.13
Section: 07.01
Weaver - Chapter 07 #10


11. Which of the following is most likely to occur if the level of glucose is low in a bacterial cell?

A. Cyclic-AMP levels will be depressed.

B. CAP will assist in stimulating transcription of the lac operon.

C. CRP activity will be inhibited.

D. Both Cyclic-AMP levels will be depressed and CRP activity will be inhibited are correct.

E. None of the choices is correct.

Blooms Level: 2. Understand

Section: 07.01
Weaver - Chapter 07 #11


12. Which of the following is true about the action of CAP at the lac promoter?

A. CAP monomer binds directly to the promoter stimulating polymerase to bind.

B. CAP-AMP blocks recruitment of polymerase to the promoter.

C. CAP blocks the αCTD of RNA polymerase.

D. Binding of the CAP-cAMP to the lac activator-binding site recruits RNA polymerase.

E. CAP monomer binds directly to the promoter stimulating polymerase to bind and CAP
blocks the αCTD of RNA polymerase are correct.

Blooms Level: 2. Understand

Section: 07.01
Weaver - Chapter 07 #12



13. Which of the following is true about the regulation of the trp operon?

A. An aporepressor is involved.

B. A corepressor is involved.

C. Attenuation is one of the mechanism of control.

D. Negative control is involved.

E. All of the choices are true.

Blooms Level: 5. Evaluate

Section: 07.03
Weaver - Chapter 07 #13


14. Which of the following is an example of an allosteric interaction?

A. allolactose binding to a repressor

B. an aptamer binding to a riboswitch

C. polymerase binding to the promoter

D. repressor binding to the operator

E. both A. allolactose binding to a repressor and B. an aptamer binding to a riboswitch

Blooms Level: 5. Evaluate

Section: 07.04
Weaver - Chapter 07 #14


15. In the process of creating a trp operon mutant, the region for the riboswitch was accidentally
deleted. Which of the following would be a likely observation in the transcription assays?

A. RNA polymerase cannot bind to the promoter.

B. The operon is permanently inhibited.

C. Attenuation would be impaired.

D. Termination would be triggered .

E. The chance of an aptamer binding to the mRNA 5′-UTR increases.

Blooms Level: 5. Evaluate

Section: 07.03
Weaver - Chapter 07 #15



16. Which of the following would be effective in blocking transcription from the lac operon in the
presence of permease?

A. antibody to RNA polymerase

B. antibody to the repressor protein

C. mutation in the operator

D. an antibody to β-galactosidase

E. both antibody to RNA polymerase and mutation in the operator

Blooms Level: 5. Evaluate

Section: 07.01
Weaver - Chapter 07 #16


17. ________ __________is the enzyme needed to bring lactose into the bacterial cell.

Galactoside permease

Blooms Level: 1. Remember
Section: 07.01
Weaver - Chapter 07 #17


18. β-galactosidase cleaves the disaccharide lactose into __________ and ____________.

glucose, galactose

Blooms Level: 1. Remember
Section: 07.01
Weaver - Chapter 07 #18


19. In the presence of glucose the lac operon is kept inactive by _________ _________.

catabolite repression

Blooms Level: 1. Remember
Section: 07.01
Weaver - Chapter 07 #19


20. The ara operon is controlled by the _____________ protein.

AraC

Blooms Level: 1. Remember
Section: 07.02
Weaver - Chapter 07 #20


21. ________ is a term used to describe a mechanism in which a protein controls it's own
regulation.

Autoregulation

Blooms Level: 1. Remember
 Section: 07.01
Weaver - Chapter 07 #21


22. Regions of the 5′-UTRs of mRNAs that alter their structures to control gene expression are
called _____________________.

riboswitches

Blooms Level: 1. Remember
Section: 07.04
Weaver - Chapter 07 #22


23. If an operon is under negative control it means that the operon is never operational.

FALSE

Blooms Level: 2. Understand
Section: 07.01
Weaver - Chapter 07 #23


24. In the absence of glucose there will be a rapid accumulation of lactose in the following mutant:
I- Oc Z+ Y-
I- O+ Z+ Y-

FALSE

Blooms Level: 5. Evaluate
Section: 07.01
Weaver - Chapter 07 #24


25. The following is an example of a cis-dominant mutation:
I-d O+ Z+ Y+ A-

FALSE

Blooms Level: 2. Understand
Section: 07.01
Weaver - Chapter 07 #25


26. Recent experimental evidence has shown that only one operator sequence is needed for
maximal expression.

FALSE

Blooms Level: 2. Understand
Section: 07.01
Weaver - Chapter 07 #26



27. One hypothesis explaining the mechanism of repression of the lac operon states that the
repressor binds to the operator and blocks access by the polymerase to the adjacent
promoter.

TRUE

Blooms Level: 2. Understand
Section: 07.01
Weaver - Chapter 07 #27


28. cAMP level is increased by the presence of high levels of glucose.

FALSE

Blooms Level: 2. Understand
Section: 07.01
Weaver - Chapter 07 #28


29. Arabinose can derepress the ara operon by causing AraC to loosen its attachment to araO2
and to bind to araI2 instead.

TRUE

Blooms Level: 2. Understand
Section: 07.02
Weaver - Chapter 07 #29


30. Attenuation causes the length of the RNA molecules to be significantly extended.

FALSE

Blooms Level: 2. Understand
Section: 07.04
Weaver - Chapter 07 #30

 7 Summary

Category # of Questions
Blooms Level: 1. Remember 7
Blooms Level: 2. Understand 11
Blooms Level: 3. Apply 1
Blooms Level: 4. Analyze 1
Blooms Level: 5. Evaluate 10
Figure 07.13 1
Section: 07.01 23
Section: 07.02 2
Section: 07.03 2
Section: 07.04 3
Weaver - Chapter 07 30