52. Progression through the phases of the cell cycle is regulated by fluctuating concentrations of ____.
a.
microtubules
b.
actin
c.
cyclins
d.
cyclin-dependent kinases
e.
histones
53. Which of the following are characteristics of cyclins?
a.
They are active only when combined with another cyclin molecule.
b.
The levels of cyclins remain constant throughout the cell cycle.
c.
The levels of cyclins fluctuate throughout the cell cycle.
d.
Cyclins add phosphate groups to target proteins.
e.
Cyclins remove phosphate groups from target proteins.
54. Signaling molecules such as peptide hormones and growth factors bind to receptors on the cell surface,
which subsequently triggers reactions in the cell. These reactions include ____.
a.
initiation of cell division
b.
stopping cell division
c.
slowing the rate of cell division
d.
causing cells to enter the G0 state
e.
both initiation of cell division and causing cells to enter the G0 state
55. Contact inhibition is an important mechanism for maintaining cell growth in developed organs and
tissues. As long as the cells remain in contact with each other they remain in ____ and are prevented
from dividing.
a.
prophase
b.
G1
c.
G2
d.
G0
e.
S
56. Contact inhibition is best explained by which of the following statements?
a.
Contact between neighboring cells triggers reactions leading to inhibition of mitosis.
b.
As neighboring cells become more tightly packed together, their size is restricted and
cytokinesis can no longer occur.
c.
As cell number increases, the protein kinases they produce compete with neighboring
cells, inhibiting mitosis.
d.
As cell number increases, the level of waste products increase, consequently slowing
metabolism leading to mitosis.
e.
As cell number increases, size restrictions inhibit protein synthesis.
57. Which one of the following characterizes cancer cells?
a.
Mitosis is strictly regulated.
b.
Cancer cells form tumors that strongly adhere to surrounding tissues.
c.
Cancer cells display uncontrolled cell division.
d.
Tumors formed by cancer cells remain encapsulated and only grow in one location.
e.
Cancer cells behave like normal cells.
58. Vinblastine, a chemotherapeutic drug used to treat breast and testicular cancers, interferes with the
assembly of microtubules. Speculate how this drug works to inhibit cancer cell growth.
a.
Vinblastine inhibits transition from G1 to S.
b.
Vinblastine inhibits transition from S to mitosis.
c.
Vinblastine inhibits cytokinesis.
d.
Vinblastine disrupts mitotic spindle formation and consequently mitosis.
e.
Vinblastine inhibits cyclin production.
59. Comparison of a cancer cell and a normal cell reveals that ____.
a.
cancer cells undergo contact inhibition, normal cells do not
b.
cancer cells do not undergo contact inhibition, normal cells do
c.
cancer cells cannot metastasize, normal cells can
d.
regulation of mitosis is strictly regulated in cancer cells, mitosis is unregulated in normal
cells.
e.
cancer cells remain adherent to other cells, normal cells do not
60. Three internal checkpoints during the cell cycle include
a.
the mitotic spindle checkpoint during G1/S.
b.
the DNA damage checkpoint during late S phase.
c.
the DNA damage checkpoint during G2/M.
d.
the mitotic spindle checkpoint during G2/M.
e.
the DNA damage checkpoint during anaphase.
61. During the mitotic spindle checkpoint,
a.
cells are in anaphase.
b.
cells arrest if chromosomes are attached properly to the mitotic spindle.
c.
cells become irreversibly committed to S phase.
d.
cells are checked for proper spindle attachment to chromosomes.
e.
cells enter G0.
62. Oncogenes are
a.
mutant forms of cell cycle genes
b.
normal forms of cell cycle genes
c.
needed for normal cells to metastasize
d.
required for normal contact inhibition of cells
e.
not used during cell division
63. The first eukaryotic genome to be elucidated was from ____.
a.
Escherichia coli
b.
Caenorhabditis elegans
c.
Drosophila melanogaster
d.
Saccharomyces cerevisiae
e.
Schizosaccharomyces pombe
64. Research with the herpes virus herpesvirus 8 focused on the transition from ____.
a.
G1 to S
b.
S to G2
c.
G1 to G0
d.
G2 to prophase
e.
telophase to cytokinesis.
65. Herpesvirus 8 encodes a protein that acts as a(n) ____.
a.
tumor suppressor
b.
transcription factor
c.
cyclin
d.
polymerase
e.
enzyme
66. Hereditary information is encoded in a single, circular DNA molecule in most prokaryotes. Which of
the following is FALSE regarding the bacterial chromosome?
a.
The DNA of the bacterial chromosome is replicated prior to segregation.
b.
Bacterial cells can replicate their DNA very rapidly.
c.
Bacterial cells utilize a mitotic spindle to segregate their replicated DNA.
d.
The bacterial chromosome has genes that control binary fission.
e.
DNA replication begins at the origin of replication.
67. Some bacteria produce the enzyme Beta-lactamase, which results in resistance to certain antibiotics
such as penicillin. Since these same organisms reproduce asexually, they produce offspring that ____.
a.
can be killed by penicillin
b.
have an abnormally high rate of mutation
c.
are resistant to penicillin
d.
have variable numbers of chromosomes
e.
can make penicillin
68. During prokaryotic cell division, two chromosomes separate and are distributed to the two ends of the
cell by ____.
a.
the action of the mitotic spindle
b.
an unknown mechanism
c.
attachment to actin
d.
attachment to separating membrane regions
e.
formation of a newly made cell wall
69. Replication of a bacterial chromosome begins at a specific region called the ____.
a.
ter
b.
replication fork
c.
beg
d.
ori
e.
rep
70. Which of the following is true about binary fission?
a.
It is thought to have evolved from mitosis.
b.
It is used in gamete formation.
c.
It results in the production of two identical daughter cells.
d.
It requires spindle formation.
e.
It is used during eukaryotic cell growth.
71. The mechanism of prokaryotic growth, DNA replication, and cell division resulting in two identical
daughter cells is called ____.
a.
mitosis
b.
meiosis
c.
binary fission
d.
budding
e.
zygote formation
72. Regarding transitions between stages of the cell cycle, scientists have
a.
already discovered many of the proteins involved
b.
figured out how the proteins communicate with each other
c.
determined how the proteins operate as small nano-machines to perform their functions
d.
shown that mammalian cells are easier to work with than Saccharomyces cerevisiae
e.
no idea which proteins are needed
73. In general, microtubules disassemble and consequently pull the chromatids to the ends of the spindle
during ____.
a.
prophase
b.
interphase
c.
anaphase
d.
metaphase
e.
telophase
74. Which of the following processes is not necessary for highly accurate mitotic cell division to occur in
eukaryotic cells?
a.
cell cycle regulation
b.
formation of the mitotic spindle
c.
two rounds of DNA replication
d.
condensation of genetic material into chromosomes
e.
segregation of sister chromatids into separate cells
75. Bacterial cells typically have ____ while eukaryotic cells have ____.
a.
a single circular chromosome; many linear chromosomes.
b.
several circular chromosomes; many linear chromosomes.
c.
one linear chromosome; many circular chromosomes.
d.
two circular chromosomes; numerous circular chromosomes depending on the species.
e.
numerous circular chromosomes depending on the species; many linear chromosomes.
Select the Exception
76. Which of the following statements is NOT true about the cell cycle?
a.
M phase is after S phase
b.
In S phase, all the DNA in the cell is duplicated
c.
G1 and G2 together encompass interphase
d.
Prophase is part of M phase
e.
Cells not actively growing are in G0
77. The stages of nuclear division include all of the following activities EXCEPT ____.
a.
movement of chromosomes into alignment on the metaphase plate
b.
separation of sister chromatids
c.
condensation of DNA into chromosomes
d.
cytokinesis
e.
disappearance of the nucleolus
78. All of the following events occur during mitosis EXCEPT ____.
a.
alignment of chromosomes at the spindle midpoint
b.
disappearance of the nuclear envelope
c.
formation of the spindle
d.
DNA synthesis
e.
separation of sister chromatids
79. Which of the following statements is NOT TRUE about sister chromatids?
a.
Sister chromatids separate from one another during prometaphase
b.
Two sister chromatids make up one chromosome
c.
Sister chromatids are generated during S phase
d.
Sister chromatids are physically attached by the centromere
e.
Sister chromatids normally end up in separate daughter cells
MATCHING
For the following question(s), identify the stage of mitosis where each of the following activities
occurs.
a.
prophase
b.
prometaphase
c.
metaphase
d.
anaphase
e.
telophase
80. Nuclear envelope disappears
81. Duplicated chromosomes condense into chromosomes
82. Mitotic spindle disassembles
83. RNA synthesis shuts down
84. Spindle fiber begins to form
85. Chromosomes align at the center of the cell
86. Sister chromatids are pulled to opposite spindle poles
87. Daughter chromosomes decondense and the nuclear envelope reforms
For each of the following statements, choose the most appropriate component of cell cycle regulation
from the choices below.
a.
CDK
b.
cyclins
c.
CDK/cyclin complex
d.
growth factors
88. Levels remain constant throughout the cell cycle
89. Turns CDK on or off
90. Levels fluctuate throughout the cell cycle
91. Regulates cell division
SHORT ANSWER
92. What is the difference between a chromosome and a chromatid?
93. How is cell division different in plants versus animal cells?
ANS:
94. What is the purpose of mitosis in living organisms?
95. What external factors influence a cell to divide?
96. Prokaryotic binary fission includes what two main features?
97. What is the main functional difference between kinetochore microtubules and nonkinetochore
microtubules?
ESSAY
98. An otherwise normal yeast cell with a diploid number of 32 chromosomes does not undergo
replication prior to M phase. What would be the result after mitosis and cytokinesis, assuming that all
processes after S phase occur properly?
99. What are the three checkpoints of the cell cycle and what is being “checked” during each one?
100. Cancer is caused by rapid cell division that results in tumor formation. Cancer cells often have
mutations in CDK genes. Explain how a mutation in a CDK might help lead to uncontrolled cell
growth.