Download mutation in lac

CAMPBELL BIOLOGY IN FOCUS
Urry • Cain • Wasserman • Minorsky • Jackson • Reece
15
Regulation of
Gene Expression
Questions prepared by
Brad Stith, University of Colorado Denver
Louise Paquin, McDaniel College
© 2014 Pearson Education, Inc.
What does the operon model attempt to explain?
A. the coordinated control of gene expression
in bacteria
B. bacterial resistance to antibiotics
C. how genes move between homologous regions
of DNA
D. the mechanism of viral attachment to a host cell
E. horizontal transmission of plant viruses
© 2014 Pearson Education, Inc.
What does the operon model attempt to explain?
A. the coordinated control of gene expression
in bacteria
B. bacterial resistance to antibiotics
C. how genes move between homologous regions
of DNA
D. the mechanism of viral attachment to a host cell
E. horizontal transmission of plant viruses
© 2014 Pearson Education, Inc.
When tryptophan (an amino acid) is present in the
external medium, the bacterium brings in the
tryptophan and does not need to make this amino acid.
Which is true when there is no tryptophan in the
medium?
A. The repressor is active and binds to the operator.
B. The repressor is inactive, and RNA polymerase
moves through the operator.
C. The operator is bound, and mRNA is made.
D. Genes are inactive.
E. The corepressor binds to the repressor.
© 2014 Pearson Education, Inc.
When tryptophan (an amino acid) is present in the
external medium, the bacterium brings in the
tryptophan and does not need to make this amino acid.
Which is true when there is no tryptophan in the
medium?
A. The repressor is active and binds to the operator.
B. The repressor is inactive, and RNA polymerase
moves through the operator.
C. The operator is bound, and mRNA is made.
D. Genes are inactive.
E. The corepressor binds to the repressor.
© 2014 Pearson Education, Inc.
Each of a group of bacterial cells has a mutation in
its lac operon. Which of these will make it
impossible for the cell to metabolize lactose?
A. mutation in lac (-galactosidase gene)
B. mutation in lac (cannot bind to operator)
C. mutation in operator (cannot bind to repressor)
D. mutation in lac (cannot bind to inducer)
© 2014 Pearson Education, Inc.
Each of a group of bacterial cells has a mutation in
its lac operon. Which of these will make it
impossible for the cell to metabolize lactose?
A. mutation in lac (-galactosidase gene)
B. mutation in lac (cannot bind to operator)
C. mutation in operator (cannot bind to repressor)
D. mutation in lac (cannot bind to inducer)
© 2014 Pearson Education, Inc.
Which element(s) from the following list constitute(s)
a bacterial operon?
A. repressor gene
B. promoter
C. inducer
D. repressor protein
E. all of the above
© 2014 Pearson Education, Inc.
Which element(s) from the following list constitute(s)
a bacterial operon?
A. repressor gene
B. promoter
C. inducer
D. repressor protein
E. all of the above
© 2014 Pearson Education, Inc.
General transcription factors in eukaryotes are
needed for all genes using the same RNA
polymerase. What is the function of specific
transcription factors? Of enhancers? How do the
enhancers stimulate the transcription initiation
complex that is so far away from the enhancers?
© 2014 Pearson Education, Inc.
Approximately what proportion of the DNA in the
human genome codes for proteins or functional
RNA?
A. 83%
B. 46%
C. 32%
D. 13%
E. 1.5%
© 2014 Pearson Education, Inc.
Approximately what proportion of the DNA in the
human genome codes for proteins or functional
RNA?
A. 83%
B. 46%
C. 32%
D. 13%
E. 1.5%
© 2014 Pearson Education, Inc.
A specific gene is known to code for three different
but related proteins. This could be due to which of
the following?
A. premature mRNA degradation
B. alternative RNA splicing
C. use of different enhancers
D. protein degradation
E. differential transport
© 2014 Pearson Education, Inc.
A specific gene is known to code for three different
but related proteins. This could be due to which of
the following?
A. premature mRNA degradation
B. alternative RNA splicing
C. use of different enhancers
D. protein degradation
E. differential transport
© 2014 Pearson Education, Inc.
RNA is cut up into small 22-nucleotide fragments to
regulate another “target” mRNA. Which of the following
is/are true?
A. The target mRNA is degraded, and its protein is not
made.
B. The RNA fragments enhance protein synthesis by
the mRNA.
C. The RNA fragments bind the ribosome to enhance use
of the mRNA and protein synthesis.
D. The target mRNA is blocked from being used in
translation.
E. The RNA fragments act on the ribosome to shut down
translation of all mRNAs.
© 2014 Pearson Education, Inc.
Even though the two cells have numerous
transcription factors and many are present in both
cells, the lens cell makes the crystallin protein (not
albumin), whereas the liver cell makes albumin (not
crystallin). Explain (draw the different situation in
each cell).
© 2014 Pearson Education, Inc.
Which methods would determine which genes are turned
on in a certain cell in an organism? (Choose more than
one answer.)
A. Use RT-PCR to identify what mRNAs are
present.
B. Use RT-PCR to measure what proteins are present.
C. Use a radioactive probe that binds only to
certain mRNAs.
D. Use a fluorescent probe that records DNA replication.
E. Use a fluorescent probe that binds to only
certain mRNAs.
© 2014 Pearson Education, Inc.
Which methods would determine which genes are turned
on in a certain cell in an organism? (Choose more than
one answer.)
A. Use RT-PCR to identify what mRNAs are
present.
B. Use RT-PCR to measure what proteins are present.
C. Use a radioactive probe that binds only to
certain mRNAs.
D. Use a fluorescent probe that records DNA replication.
E. Use a fluorescent probe that binds to only
certain mRNAs.
© 2014 Pearson Education, Inc.