51. A miRNA’s normal job is to inactivate a tumor suppressor gene. If this miRNA is made in abnormally
high amounts,
a.
the cell will become cancerous
b.
the tumor suppressor gene will be overactive
c.
the cell will not express the tumor suppressor gene as highly as it should
d.
the cell will stop growing
e.
the cell will begin to differentiate
52. What is the role of CREB in a white blood cell?
a.
It is a tumor suppressor protein.
b.
It stimulates the activity of p53.
c.
It binds to CRE and activates cell division.
d.
It increases cAMP production during an infection.
e.
It decreases cAMP production during an infection.
53. How does the Tax protein contribute to the increased growth rate of white blood cells?
a.
It stabilizes the CREB dimers that bind to the CRE DNA sequence.
b.
It inhibits the ability of CREB to bind to DNA.
c.
It phosphorylates the CREB activator protein.
d.
It allows CREB to bind the CRE-like viral enhancer.
e.
It stimulates the production of cAMP in a cell.
54. Chromatin remodeling
a.
is subject to well-characterized stages of regulation by the cell.
b.
blocks access to genes that should not be expressed in a particular cell.
c.
is unaffected by alterations to the DNA sequences of a cell.
d.
results in specific patterns of gene expression.
e.
is generally independent of histone protein arrangements.
55. RNAi could be used to treat macular degeneration by
a.
preventing the development of excess blood vessels.
b.
increasing the turnover rate of blood vessels in the retina.
c.
preventing the replication of the virus that causes macular degeneration.
d.
blocking expression of the viral genes that allow infection of retinal cells to occur.
e.
stimulating the capillaries to tighten their walls, preventing the plasma leakage that clouds
vision.
56. A key difference between eukaryotic and prokaryotic genomes is
a.
the lack of controls of gene expression in prokaryotes.
b.
the physical arrangement of genes on the chromosome(s).
c.
the near simultaneous transcription and translation that occurs in eukaryotes and is strictly
sequential in prokaryotes.
d.
the physical separation of transcription and translation in prokaryotes compared to no
separation of the processes in eukaryotes.
e.
the regulation of the cell cycle by eukaryotes which is not observed in prokaryotes.
57. In prokaryotes, which of the following types of regulation will NOT occur?
a.
chromatin remodeling
b.
variations of mRNA turnover
c.
variations in protein turnover
d.
activation of promoters
e.
regulation of transcription
58. When comparing gene regulation in prokaryotes and eukaryotes,
a.
both significantly remodel chromatin
b.
both have transcription and translation in separate cellular compartments
c.
both produce differentiated cells
d.
both use transcription control
e.
both have alternative splicing
59. Which of the following is NOT a form of regulation of gene expression?
a.
transcriptional regulation
b.
translational regulation
c.
pretranscriptional regulation
d.
posttranscriptional regulation
e.
posttranslational regulation
60. Which of the following is NOT a reason why eukaryotic gene regulation is more complicated than
prokaryotic gene regulation?
a.
Eukaryotic DNA is sequestered in the nucleus.
b.
Eukaryotic DNA is complexed with histones.
c.
Eukaryotic transcription is completed before translation begins.
d.
Multicellular eukaryotic organisms produce many different types of cells.
e.
Eukaryotic regulatory sequences are scattered throughout the genome.
61. Which of the following will NOT result in a proto-oncogene’s conversion into an oncogene?
a.
A mutation in the proto-oncogene’s promoter that increases transcription of the gene.
b.
A mutation in the coding sequence of a protein that renders a protein abnormally active.
c.
An alteration to the p53 coding sequence rendering the p53 protein inactive.
d.
An introduction of new DNA sequences to a chromosome that alters the regulation of the
cell cycle.
e.
The translocation of a proto-oncogene to a location in the cell and under the control of a
more active promoter than present in the original location.
MATCHING
Match each of the following terms with its correct definition.
a.
A regulatory protein that activates the expression genes
b.
Interfering RNA molecules encoded by nuclear DNA
c.
A process of controlling the expression of genes that takes place at the DNA level
d.
A regulatory protein that prevents genes from being expressed
e.
The inhibition of transcription via DNA methylation
f.
Interfering RNA molecules associated with some viral life cycles
g.
A tumor that is comprised of cells that invade and disrupt the surrounding tissues
h.
The presence of this molecule, such as allolactose, will increase expression of an operon’s
genes
i.
A cluster of prokaryotic genes and their associated DNA regulatory sequences
j.
A tumor that is comprised of undifferentiated cells that stay together in a single mass
k.
The spread of malignant cells through the blood or lymphatic system
l.
One example of this would be removing a nucleosome from DNA to expose a promoter
62. miRNA
63. repressor
64. malignant
65. activator
66. chromatin remodeling
67. transcriptional regulation
68. silencing
69. inducer
70. siRNA
71. operon
72. benign
73. metastasis
356
357
Labeling
Identify each labeled part of the following illustration of eukaryotic DNA.
74. activators
75. coactivator multiprotein complex
76. promoter
77. transcription initiation site
78. enhancer
79. proximal promoter region
80. RNA polymerase
358
Labeling
Identify each labeled part of the following illustration.
81. lacZ
82. promoter
83. lacY
84. transcription termination site
85. regulatory gene
86. lac operon
87. lac repressor
88. lacI
89. lacA
90. operator
91. RNA polymerase
92. transcription initiation site
SHORT ANSWER
93. Explain the difference between benign and malignant tumors.
94. Compare DNA methylation to histone acetylation.
95. Explain the concept of combinatorial gene regulation in eukaryotes.
96. Assume that a bacterial cell produces a lac repressor that is able to bind to the operator sequence of the
lac operon but cannot bind allolactose. Explain the effect of transcription of the lac operon when
lactose is not present, and then when it is present.
97. Explain how dicer and RISC are involved in the production and function of miRNAs.
98. Describe the relationships among induction, determination, and differentiation.
99. Many breast cancers involve mutations in the BRCA1 gene. Explain the difference between sporadic
and familial breast cancer caused by this gene at a molecular level.
OTHER
100. Imagine you are tracing the regulatory journey of a single protein being expressed in a single cell.
There are multiple stages of regulation, and many of them can only occur in a particular order. Write
the letter of the first regulatory step next to 1 and the letter of the last stage of regulation next to 8.
A.
Regulation of transcription initiation
B.
Protein breakdown
C.
Pre-mRNA processing
D.
Protein modification
E.
Chromatin remodeling
F.
RNA interference
G.
Initiation of translation
H.
mRNA breakdown
1.
2.
3.
4.
5.
6.
7.
8.
ANS:
1.
E
2.
A
3.
C
4.
F
5.
G
6.
H
7.
D
8.
B
MODIFIED TRUE/FALSE
If the statement is true, answer “T“. If the statement is false, answer “F” and make it correct by
changing the underlined word(s) and writing the correct word(s) in the answer blank(s).
101. An operator and transcription unit are called an operon.
102. Many eukaryotic operons are subject to numerous regulatory mechanisms.
103. Eukaryotic genes are organized into operons.
104. Eukaryotic genes consist of protein-coding sequences and adjacent regulatory sequences.
105. Acetylation is irreversible.
106. Each steroid hormone can bind to its own steroid hormone response unit (SHRU) but not to the SHRU
associated with other steroid hormones.
107. When DNA is imprinted, the methylation pattern is preserved.
108. RNAi is a key regulator of transcription.
109. The DNA encoding siRNA is not normally found in the nucleus.
110. There is a direct correlation between the level of translation and the length of a poly-A tail.
111. A benign tumor is usually not life-threatening.
112. RNAi could be used to treat macular degeneration in the future.
ESSAY
113. The default state for the lac operon is off, while the default state for the trp operon is on. Explain this
contradiction and the mechanism of control via the repressor proteins.
114. When comparing gene regulation in prokaryotes to that in eukaryotes, which is better? Justify your
answer.
115. Describe the functions of maternal effect genes, segmentation genes, and homeotic genes. In your
answer, include the effects of mutations in each category of gene.