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Multiple Choice Quiz
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1
___________ is the premature termination of transcription.
A)Induction
B)Attenuation
C)Repression
D)Catabolite repression
E)all of the above
2
Gene regulation involving premature termination of transcription is:
A)operator
B)promoter
C)repressor
D)attenuation
E)inducer
3
LacI repressor binds to the:
A)operator
B)promoter
C)repressor
D)attenuator
E)inducer
4
A molecule that causes increased expression of genes is a(n):
A)operator
B)promoter
C)repressor
D)attenuator
E)inducer
5
RNA polymerase binds to the:
A)operator
B)promoter
C)repressor
D)attenuation
E)inducer
6
A protein that blocks access of DNA to RNA polymerase acts as a(n):
A)operator
B)promoter
C)repressor
D)attenuation
E)inducer
7
Many genes can be regulated at once through the action of a(n):
A)operon
B)heat shock protein
C)sigma factor
D)corepressor
E)leader sequence
8
Which statement is not true regarding global gene regulation in bacteria?
A)many genes can be induced at the same time
B)a different sigma factor is used for each operon
C)the core RNA polymerase remains the same
D)many genes can be shut down at the same time
E)environmental factors can begin regulatory cascade
9
For the E. coli genotype I+P+OcZ+Y+A+, the expression of ß-galactosidase will be:
A)inducible
B)constitutive
C)absent
D)lethal
E)none of the above
10
For the E. coli genotype I-P+O+Z+Y+A+, the expression of ß-galactosidase will be:
A)inducible
B)constitutive
C)absent
D)lethal
E)none of the above
11
Which of the following lac operon genes is not linked to its correct function?
A)lacI - encodes for the repressor protein
B)lacY - encodes for lac permease
C)lacZ - encodes for β-galactosidase
D)lacA - encodes for transacetylase
E)all of the above are correct
12
If the lacI gene is transcribed, which of the following environmental conditions is correct?
A)lactose is present
B)lactose is absent
C)glucose is present
D)glucose is absent
E)none of the above
13
The phenotype of a CRP null mutant would be:
A)weakly inducible β-galactosidase
B)constitutive β-galactosidase production
C)completely repressed β-galactosidase
D)strongly inducible β-galactosidase
E)none of the above
14
lacI is a ________; the trp attenuator is a ________.
A)cis acting element; cis and trans acting element
B)cis acting protein; trans acting element
C)cis acting element, trans acting protein
D)trans acting protein, cis acting element
E)trans acting protein; trans acting element
15
Once transcription has begun, which of the following can regulate expression of the mRNA?
A)promoter
B)operator
C)sigma factor
D)repressor
E)none of the above
16
The helix-turn-helix motif is an example of:
A)a regulatory protein motif
B)an operator motif
C)a promoter motif
D)a leader sequence motif
E)a rho-independent transcriptional terminator motif
17
The 434 and P22 bacteriophages each contain recognition a helices that bind their respective operators specifically to repress transcription. If the 434 recognition a helix on the 434 protein is replaced with the P22 recognition a helix and the appropriate host is infected, what will happen?
A)P22 genes will be repressed
B)434 genes will be repressed
C)no genes will be repressed; the repressor will be rendered inactive
D)both P22 and 434 genes will be repressed
E)P22 genes will be activated
18
Which is not a property of a sigma factor?
A)initiates translation
B)binds to DNA
C)binds RNA polymerase holoenzyme
D)initiates transcription
E)regulates multiple operons
19
Which of the following is involved in the negative regulation of transcription?
A)CRP binding
B)LacI binding
C)AraC binding
D)none of the above are negative control mechanisms
E)all of the above are negative control mechanisms.
20
In the absence of arabinose, the AraC protein induces a regulatory secondary structure in _________.?
A)protein
B)DNA
C)mRNA
D)1 and 2
E)all of the above
21
Vibrio cholerae virulence genes:
A)are induced by environmental cues
B)are regulated by ToxT
C)are constitutively expressed
D)1 and 2
E)none of the above
22
Which of the following sequences is most likely to be a regulatory site?
A)5' - CATTCGATTCTT - 3'
B)5' - GGCGCTACGGA - 3'
C)5' - ATATTTATACCTT - 3'
D)5' - CGATACGACTTG - 3'
E)5' - ATGTCCGTACAT - 3'
23
In the lac operon, under which of the following conditions will the lac genes be transcribed at high levels?

A. low glucose, low lactose
B. high glucose, low lactose
C. low glucose, high lactose
D. high glucose, high lactose

A)C
B)D
C)C and D
D)A and C
E)none of the above
24
You are interested in testing the attenuation model of regulation in the trp operon. You have cloned the entire trp operon and, using site-directed mutagenesis, you have mutated segment 2 in the 5' end of the mRNA for the tryptophan biosynthetic enzymes such that it can no longer base-pair with segment 3 (see Figure 15.30). The total number of base pairs in the region and the spacing between segments have not been altered. You transfect the plasmid encoding this mutated transcript into E. coli cells that are completely deficient for the trp operon and find that the transformed cells are:
A)able to make the trp biosynthetic proteins only in the absence of trp
B)unable to make the trp biosynthetic proteins even in the complete absence of trp
C)able to make the trp biosynthetic proteins whether trp is present or not
D)able to make the trp biosynthetic proteins only in the presence of trp
E)unable to make the trp biosynthetic proteins only in the presence of trp
25
You want to understand the regulation of a particular Salmonella gene (X). You believe it is regulated by a repressor and you try to isolate the gene that encodes this repressor. First, you make a reporter construct by fusing the promoter of geneX to the lacZ gene that encodes ?-galactosidase. You create a library by cutting Salmonella genomic DNA into pieces using partial digestion or sonication and cloning these into an expression vector that can replicate in E. coli. Expression vectors contain a promoter so your protein will be transcribed and translated. To perform the experiment, you use your library to transform E. coli cells containing the reporter construct and plate the cells on X-Gal (plus inducer). The results are indicated below:

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Based on the results above, you conclude that geneX is normally ______ in the absence of any regulators. You also conclude that your experiment worked and you proceed with the next step by picking ________ colonies from the vector + library plate and isolating your negative regulator.
A)off; white
B)off; blue
C)on; white
D)on; blue
E)on; blue and white







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