Download BI0I 121 cell and tissues

LESSON – 30
THE EUKARYOTIC CHROMOSOME.
A.
Objectives
—
—
B.
define haploid, diploid, centromere, chromatin, chromatid, chromosome, nucleus,
nucleoslus, nucleosome, histones, mitosis, cytokinesis, binary fission, centromere,
centriole, spindle figure, aster, spindle equator.
explain the structure of chromosomes from nucleic acid strand to DNA, to chromatid
and chromosome.
Lecture outline
READ: Eukaryotic chromosomes (SBM p212-215)
1.
THE EUKARYOTIC CHROMOSOME
Read:
Chromosomes are highly ordered structured (R&J p209-211)
a. history
b. human chromosomes
c. structure
LESSON-31
CELL CYCLE AND MITOSIS
A.
Objectives
—
-
B.
Define haploid, diploid, centromere, chromatin, chromatid, chromosome, nucleus,
nucleoslus, nucleosome, histones, mitosis, cytokinesis, binary fission, centromere,
centriole, spindle figure, aster, spindle equator.
State the different phases of the eu]caryotic cell cycle and tell what happens during each
phase; contrast division of the eukaryotic to that of the prokaryotic cell; compare
cyokinesis of plant and animal cells.
Describe the different phases of mitosis; relate mitosis to DNA duplication; make
cartoon pictures of mitosis; explain the origin of the nuclear envelope, the shortening of
the spindle fibers.
Lecture outline
READ: The cell cycle and mitosis (SBM p215-221
2.
THE CELL CYCLE
3.
MITOSIS
a.
b.
c.
d.
4.
prophase: formation of mitotic apparatus
metaphase: division of centromeres
anaphase: separation of chromatids
telophase: reformation of nucleus
CYTOKINESIS
a. animal cells
b. plant cells.
5.
CELL DIVISION IN PROKARYOTES
LESSON - 32.
CONTROL OF THE CELL CYCLE.
A. Objectives.
—
-
Describe the general nature of cell cycle control; explain the goal of the G1, G2 and M
check points; define cyclin, cyclindependent kinase, mitosis—proinoting factor,
proteasome, ubiquitin and ubiquinated cyclin.
Discuss the relationship between growth factors and the cell cycle; relate cell cycle
control and cell-cell signaling.
B. Lecture outline.
READ: Regulation of the cell cycle (SBM p221-223)
1. General strategy of cell cycle control.
2. Molecular mechanisms of cell cycle control.
- the G2 check point.
- the G1 check point.
- the M checkpoint
3. Controlling the cell cycle in multicellular eukaryotes.
4. Growth factors and the cell cycle.
C. Study Questions.
1.
The bacterial genome exists as a
A.
single, circular, double— stranded DNA molecule.
B.
single, circular, single— stranded DNA molecule.
c.
single, circular, single— stranded RNA molecule.
D.
number of small, circular DNA loops.
B.
number of protein-bound DNA molecules.
2.
The division of the bacterial cell. occurs as the
A.
cell wall develops cracks around the equator of the cell.
B.
chromosomes are pulled toward opposite ends of the cell.
C.
cytoplasm forms a cell plate across the middle of the cell.
D.
microfilaments and microtubuJ~es constrict the cytoplasm.
B.
plasma membrane pinches inward constricting the cell..
3.
A major difference between prokaryotes and eukaryotes is that eukaryotes have
A.
DNA strung out as much longer double—stranded molecules.
B.
many more small, circular DNA molecules.
c.
more DNA but smaller cells because of less protein and lipid.
D.
much larger quantities of DNA.
E.
several DNA molecules attached to the cell. membrane.
4.
The number of chromosomes characteristic of eukaryotic species
A.
are determined without the use of a microscope.
B.
are predicted from the size of the organism.
C.
changes as the animal or plant grows and ages.
D.
varies considerably from species to species, from 2 to l00s.
E.
varies from one cell to another within each plant or animal..
5.
What criteria distinguish between a prokaryotic and eukaryotic ‘chromosome’?
A. Shape.
B.
Presence of protein.
C.
Method of replication.
D. Organellar packaging.
E.
all of the above.
6.
Eukaryotic chromosomes are composed of chromatin that is about
A. 60% protein, 40% RNA.
B.
60% protein, 40% DNA.
C.
90% protein, 10% DNA.
D. 10% protein, 90% DNA.
E.
1% protein, 98% DNA, 1% RITA.
7.
The proteins of chromosomes are called
A. albumins.
B.
antibodies.
C.
enzymes.
D. nucleosomes.
E.
histones.
8.
What is the (electric) charge and corresponding name of histones?
A. positive, cationic.
B.
C.
D.
negative, cationic.
positive, anionic.
negative, anionic.
9.
Nucleosomes
A. contain noncoding DNA.
B.
are formed by DNA wound around a core of histones.
C.
are characteristic of prokaryotes.
D. have a envelope composed of two membranes.
E.
are the site of assembly of the ribosomes.
10.
Chromosomes shorten and thicken as the string of nucleosomes twists into
A. braids.
B.
loops.
C.
ropes.
D. supercoiJ.s.
E.
chromatids.
11.
Highly condensed and densely stained portions of the chromatin, some of which are never expressed, are
known as
A. dark bands or dark sections.
B.
euchromatin.
C.
heterochromat in.
D. sister chromatids.
E.
homologous chromosomes.
12.
The particular array of chromosomes that characterizes a human being is called the
A. eukaryote.
B.
genome.
C.
hapJ.oid complement.
D. homologous pairs.
E.
karyotype.
13.
Human body cells contain 2 sets of chromosomes; human cells are
A. complementary.
B.
diploid.
C.
haploid.
D. homogeneous.
E.
replicated.
14.
What is the number of chromosomes of a human cell?
A. 13.
B.
18.
C.
23.
D. 37.
E.
46.
15.
What is the number of chromosomes of the human haploid complement?
A. 13.
B.
18.
C.
23.
D. 37.
E.
46.
16.
Two human chromosomes that are structurally and morphologically alike and carry essentially identical
genetic information are
A. a basic set.
B.
a homologous pair.
C.
a karyotype.
D. members of the same haploid complement.
E.
sister chromatids.
17.
What is the number of chromatids present in a homologous pair of chromosomes during the G 1 phase of the
cell cycle?
A.
1
B.
2.
C.
3.
D.
4.
E.
5.
18.
What is the number of chromatids present in homologous pair of chromosomes during the G 2 phase of the cell
cycle?
A.
1
B.
2.
C.
3.
D.
4.
E.
5.
19.
What is NOT a recognized phase of the cell cycle?
A.
G1.
B.
S.
C.
G2
D.
mitosis
E.
cytokinesis
20.
What is the phase of the cell cycle when cellular DNA is replicated?
A.
G1.
B.
S.
C.
G2.
D.
mitosis
E.
cytokinesis
21.
During what phase of the cell cycle does the cell increase in size and does most of its day-today tasks?
A.
G1.
B.
S.
C.
G2.
D.
mitosis.
E.
cytokinesis.
22.
What is the phase of the cell cycle during which the cytoplasm is divided?
A.
G1.
B.
S.
C.
G2.
D.
mitosis.
E.
cytokinesis.
23.
Once the genetic material is duplicated in preparation for mitosis, each chromosome is double. Each half is
called a
A.
B.
C.
D.
E.
brother.
centromere.
chromatid.
sister.
chromatin.
24.
What is the name for the disk of protein that is part of the centromere of each chromosome to which the
spindle fibers attach?
A.
centromere plate.
B.
karyotype.
C.
kinetochore.
D.
microtubular attachment site or MAT.
E.
spindle fiber hook.
25.
The first stage of mitosis during which the chromosomes condense, i. e., become visibly shorter and thicker, is
the
A.
anaphase.
B.
interphase.
C.
metaphase.
D.
prophase.
E.
telophase.
26.
During the first part of mitosis the nucleolus ceases to be visible under the microscope. This happens because
A.
chromosomal DNA and protein are stored in the nucleolus.
B.
dye is no longer attracted to the constituents of the
nucleolus.
C.
ribosomal RNA assembly stops when the chromosome condense
D.
the nucleolus is used up in making the spindle
microtubuJ.es.
E.
the nucleolus is used up in the thickening of chromosomes.
27.
The framework of microtubules that appears in the cell and eventually moves the chromatids apart is the
A.
aster.
B.
bridge.
C.
cell plate.
D.
centriole.
E.
spindle fibers.
28.
Microtubules become attached to each sister chromatid at the
A.
aster.
B.
centriole.
C.
centromere.
D.
imaginary plane.
E.
opposite ends.
29.
The chromosomes line up with their centromere in the equatorial plane of the spindle during
A.
anaphase.
B.
interphase.
C.
metaphaee.
D.
prophase.
E.
telophase.
30.
If, because microtubuj.es became improperly attached to the kinetochores, two sister chromatids fail to
separate at the end of metaphase, a likely result is that
A.
B.
C.
D.
E.
31.
32.
both chromatids will remain at the equator of the spindle.
the mitosis process will stop immediately.
one daughter cell will be missing all its chromosomes.
one daughter cell will be missing one chromosome.
prophase runs backwards until a proper connection is made.
Microtubules become shorter because A. tubu].in molecules are digested.
B.
tubulin molecules are pulled past each other.
C.
microtubules undergo supercoiling.
D.
tubulin subunits are removed at the polar end.
E.
tubulin subunits are removed at the middle.
Microtubules become shorter, pulling chromatids to the poles of the spindle, during
A. anaphase.
B. interphase.
C.
metaphase.
D. prophase.
E.
telophase.
33.
Mitochondria and chloroplasts divide during
A. anaphase.
B. cytokinesis.
C.
G3 phase.
D. G2 phase.
E.
telophase.
34.
The cell is cleaved into two approximately equal halves, each with about the same amount of cytoplasm and
cell organelles, during
A. anaphase.
B. cytokinesis.
C.
G3 phase.
D. G2 phase.
E.
telophase.
35.
Animal cells typically achieve cytokinesis by way of
A. binary fission.
B. a cell plate across the middle of the cell.
C.
a cleavage furrow that pinches the cell in two.
D. membranes of the ER across the width of the cell.
E.
a process known as belt tightening.
36.
What cellular structures contract during cytokinesis of animal cells?
A. actin filaments (micro filaments).
B. microtubules.
C.
chromatins.
D. endoplasmic reticulum.
E.
centrioles.
37.
Plant cells typically achieve cytokinesis by
A.
binary fission.
B.
a cell plate across the middle of the cell.
C.
a cleavage furrow that pinches the cell in two.
D. membranes of the ER across the width of the cell.
E.
a process known as belt tightening.
38.
When a plant cell divides in two, new wall material is exuded into space between the two membranes of the
A.
nucleus.
B.
endoplasmic reticulum.
C.
chloroplasts.
D. spindle microtubules.
E.
cell plate.
39.
The number of DNA molecules of a chromatid is
A.
1
B.
2
C.
3
D.
4
E.
many
40.
When DNA synthesis begins,
A.
the two strands of the double helix condense tightly for base-pair transfer.
B.
the two strands of the double helix unwind from each other.
C.
two DNA molecules bond.
D. the old strands move to find new strands before bonding.
E.
the old strands disintegrate in individual nucleot ides.
41.
Which of the following sequences of the cell cycle phases is characteristic of eukaryotic cells?
A.
G to S to M.
B.
Gl to S to G2 to M to C.
C.
S to M to C.
D. Gl to G2 to S to C.
E.
Gl to G2 to G3 to S to C.
42.
Which of the following are the checkpoints for cell cycle control?
A.
G1 checkpoint.
B.
G2 checkpoint.
C.
M checkpoint.
D. S checkpoint.
E.
G1, G2, and M checkpoints.
43.
Cell growth is assessed at the
A.
G1 checkpoint.
B.
G2 checkpoint.
C.
M checkpoint.
D. S checkpoint.
E.
GO checkpoint.
44.
DNA replication is assessed at the
A.
G1 checkpoint.
B.
G2 checkpoint.
C.
M checkpoint.
D. S checkpoint.
E.
GO checkpoint.
45.
Mitosis is assessed at the
A.
G1 checkpoint.
B.
G2 checkpoint.
C.
M checkpoint.
D.
E.
S checkpoint.
GO checkpoint.
46.
The cells assesses whether all chromosomes are properly attached to the spindle at the
A.
G1 checkpoint.
B.
G2 checkpoint.
C.
M checkpoint.
D. S checkpoint.
E.
GO checkpoint.
47.
The M checkpoint occurs at
A.
G1 phase.
B.
prophase.
C.
metaphase.
D. anaphase.
E.
G2 phase.
48.
The checkpoint that controls the cells entry into mitosis is the
A.
G1 checkpoint.
B.
G2 checkpoint.
C.
M checkpoint.
D. S checkpoint.
E.
GO checkpoint.
49.
It would be disastrous for a cell to’ enter mitosis before replicating all its chromosomal DNA. Unreplicated
DNA inhibits the cell cycle at the
A. Gl checkpoint.
B. G2 checkpoint.
C.
M checkpoint.
D. S checkpoint.
E.
GO checkpoint.
50.
Replication of severely damaged DNA would fix mutations in the genome. Irradiated or chemically modified
DNA inhibits the cell cycle at the
A. G1 checkpoint.
B. G2 checkpoint.
C.
M checkpoint.
D. S checkpoint.
E.
GO checkpoint.
51.
severely damaged DNA causes chromosomal rearrangements and aneuploidy and therefore inhibits the cell
cycle at the
A. G1 checkpoint.
B. G2 checkpoint.
C.
M checkpoint.
D. S checkpoint.
E.
GO checkpoint.
52.
Defect in assembly of the mitotic spindle or in the attachment of the kinetochores to spindle microtubules
leads to polyploidy and aneuploidy and therefore inhibits the cell cycle 57. at the
A. Gl checkpoint.
B. G2 checkpoint.
C. M checkpoint.
D. S checkpoint.
53.
E. GO checkpoint.
The proteins that participate in the functioning of the cell cycle checkpoints are
A.
asters and centrioles.
B.
histones and nucleosomes.
C.
centromeres and kinetochores.
D.
cyclins and cyclin-dependent kinases (cdk).
E.
microfilaments and microtubules.
54.
During the cell cycle the concentration of ________ remains constant, whereas the concentration of
________ gradually builds up and then rapidly declines.
A. G1 protein, G2 protein.
B.
G2 protein, G1 protein.
C.
cyclin-dependent kinase, cyclin.
D. cyclin, cyclin-dependent kinase.
E.
M factor, S factor.
55.
The cytoplasm of a cell starting S phase contains
A. active Gl cyclin-cdk.
B. inactive G1 cyclin-cdk.
C. inactive G2 cyclin-cdk.
D. active G2 cyclin-cdk.
E. active M cyclin-cdk.
56.
The cytoplasm of a cell starting mitosis contains
A. active G1 cyclin-cdk.
B.
inactive G1 cyclin-cdk.
C.
inactive G2 cycJ.in-cdk.
D. active G2 cyclin-cdk.
E.
active M cyclin-cdk.
57.
Mitosis-promoting factor (MPF) is
A. active Gl cyclin-cdk.
B.
inactive G1 cyclin-cdk.
C.
inactive G2 cyclin-cdk.
D. active G2 cyclin-cdk.
E. E. active M cyclin-cdk.
58.
The G1 checkpoint of yeasts is called
A. restriction point.
B. start.
C. begin.
D. S.
E. MPF.
59.
Mitosis-promoting factor stimulates
A.
chromosome condensation.
B.
mitotic spindle formation.
C.
nuclear envelope breakdown.
D.
proteolytic activity.
E.
all of the above.
60.
Cyclin cyclin—dependent kinases induce progression of the cell cycle by
A.
cleavaging peptide bonds.
B.
C.
D.
E.
polymerization of nucleotides.
phophorylation of proteins.
hydrolysis of oligosaccharides.
oxidation of simple aldehydes.
61.
Cyclins are rapidly destroyed by A. cdk-mediated phosphorylation.
B.
cdk—mediated dephosphorylation.
C.
phosolipase C activity.
D.
ubiquit in-dependent proteolys is.
E.
lysosomal digestion.
62.
Proteasomes are
A.
beads of proteins.
B.
nucleosomes.
C.
polysomes.
D.
centrosomes.
E.
multiprotease complexes.
63.
Proteasomes degrade
A.
polysaccharides.
B.
proteins.
C.
nucleic acids.
D.
triglycerides.
E.
phospholipids.
64.
Cytoplasmic proteins destined for degradation by proteasomes are marked by the small protein
A.
insulin.
B.
glutathione.
C.
ubiquitin.
D.
cytochrome C.
E.
actin.
65.
The cycle of a cell is controlled from the outside by
A.
contact with neighboring cells.
B.
the presence of growth factors.
C.
internal, autonomous clock.
D.
both A and B are correct.
E.
both A, B, and C are correct.
66.
The action of stimulating or inhibiting growth factors is linked to cyclin cyclin—dependent kinases by A.
signal transduction pathways.
B.
metabolic conversion of procarciflogefls.
C.
polyubquitination of proteins.
D.
mitosis.
E.
oxidative phosphorylation.
67.
If a cell in G1 phase is fused with a cell in S phase then
A.
chromosomes of the original S phase cell complete anaphase.
B.
DNA synthesis begins in the nucleus of the original G1 cell.
C.
chromosomes of the original S phase cell condense.
D.
chromosomes of the original G1 cell condense.
E.
chromosomes of the original G1 cell complete anaphase.
68.
If a cell in G2 phase is fused with a cell in M phase then
A.
DNA synthesis begins in the nucleus of the original G2 cell.
B.
DNA synthesis begins in the nucleus of the original M phase cell.
C.
chromosomes of the original M phase cell condense.
D.
chromosomes of the original G2 phase cells condense.
E.
chromosomes of the original G2 cell complete anaphase.
69. A bacterial chromosome consists of:
A.
B.
C.
D.
E.
a linear DNA molecule many times larger than the cell.
a circular DNA molecule many times larger than the cell.
a circular DNA molecule smaller than the cell.
a linear DNA molecule smaller than the cell.
a linear or circular DNA molecule smaller than the cell.
70. Eukaryotic chromosomes consist of:
A.
B.
C.
D.
E.
circular DNA molecules complexed with positively charged nonhistone proteins.
circular DNA molecules complexed with negatively charged histone proteins.
linear DNA molecules complexed with positively charged histone proteins.
linear DNA molecules complexed with negatively charged histone proteins.
circular DNA molecules.
71. Nucleosomes are best described as:
A.
B.
C.
D.
E.
eukaryotic DNA associated with histone proteins.
prokaryotic DNA associated with nonhistone proteins.
eukaryotic DNA associated with nonhistone proteins.
prokaryotic DNA associated with histone proteins.
eukaryotic DNA associated with scaffolding proteins.
72. Each nucleosome has
A.
B.
C.
D.
E.
base pairs of DNA wrapped around a disc-shaped core of eight histone molecules.
146
28
18
10,000
456
73. What is the function of nucleosomes?
A.
B.
C.
D.
E.
To prevent DNA strands from tangling.
To help DNA replicate.
To make RNA synthesis possible.
To prevent RNA from tangling with DNA during transcription.
None of these.
74. Nucleosomes are organized into large coiled loops in visible chromosomes by:
A.
B.
C.
D.
E.
histones.
centromeres.
kinetochore proteins.
scaffolding proteins.
condensins.
75. The cell cycle of a typical somatic cell consists of ____________ and M phase.
A.
B.
C.
D.
E.
interphase
meiosis I
crossing-over
meiosis II
mitosis
76. The M phase of the cell cycle involves two main processes:
A.
B.
C.
D.
E.
mitosis and cytokinesis.
meiosis I and meiosis II.
homologous pairing and crossing-over.
interphase and mitosis.
mitosis and meiosis.
77. Once nerve cells become mature, they don’t usually undergo cell division. Based on your knowledge of the cell
cycle, you would predict that mature nerve cells become arrested in the ____________ of the cell cycle.
A.
B.
C.
D.
E.
G0 phase
S phase
prophase
G1 phase
G2 phase
78. Chromosomes are duplicated during
A.
B.
C.
D.
E.
of the cell cycle.
G1 phase
G2 phase
S phase
metaphase
prophase
79. Which of the following represents the sequence of events during mitosis?
A.
B.
C.
D.
E.
prophase — metaphase — anaphase — telophase
interphase — metaphase — anaphase — telophase
anaphase — telophase — metaphase — interphase
interphase — prophase — anaphase — metaphase
metaphase — telophase — anaphase — prophase
80. If a cell is in G2:
A.
B.
C.
D.
E.
it has twice the amount of DNA present in a telophase nucleus.
it has visibly distinct chromosomes.
it lacks a visible nuclear membrane.
it is in mitosis.
it is in cytokinesis.
81. During prophase, ____________ is/are compacted into visible chromosomes.
A.
B.
C.
D.
E.
chromatin
centrioles
centromeres
kinetochores
colchicine
82. The ____________ is responsible for the separation of the chromosomes during ____________ of mitosis.
A.
B.
C.
D.
E.
cell wall; anaphase
flagellum; metaphase
mitotic spindle; anaphase
kinetochore; prophase
centromere; telophase
83. ____________ contain identical DNA sequences and are held together by ____________ during mitosis.
A.
B.
C.
D.
E.
Daughter chromosomes; hydrogen bonding
Daughter chromosomes; ionic bonding
Sister chromatids; spindle fibers
Sister chromosomes; histone proteins
Sister chromatids; centromeres
84. The mitotic spindle is made of:
A.
B.
C.
D.
E.
collagen.
condensin.
histones.
keratin.
microtubules.
85. The kinetochore serves which of the following functions?
A.
B.
C.
D.
E.
Kinetochores anchor spindle fibers to the centrioles.
Kinetochores are the site of DNA synthesis.
Kinetochores regulate the length of the cell cycle.
Kinetochores attach to microtubules during mitosis.
Kinetochores are involved in cytokinesis.
86. All of the following events occur during prometaphase EXCEPT:
A.
B.
C.
D.
E.
the nuclear envelope breaks down.
the nucleoli disappear.
the mitotic spindle is completely assembled.
the spindle fibers “capture” chromosomes.
the duplicated chromosomes become visible with the light microscope.
87. A cell is in metaphase if:
A.
B.
C.
D.
E.
the chromosomes are visible as threadlike structures.
the nuclear envelope is clearly visible.
the chromosomes are aligned at the midplane of the cell.
the chromosome are separated into distinct groups at opposite poles of the cell.
None of the above.
88. Duplicated centrioles move to opposite poles of a dividing ____________ cell during ____________ of the cell
cycle.
A.
B.
C.
D.
E.
plant; metaphase
plant; anaphase
prokaryotic; metaphase
animal; interphase
animal; prophase
89. The chromosome makeup of an individual organism is called a:
A.
B.
C.
D.
E.
kinetochore.
chromosome plot.
centromere.
karyotype.
centriole.
90. Chromosomes are condensed to their greatest extent during
A.
B.
C.
D.
E.
of mitosis.
metaphase
prophase
telophase
interphase
anaphase
91. Cytokinesis in animal cells involves contraction of a ring of ____________ microfilaments.
A.
B.
C.
D.
E.
tubulin plus actin
actin plus myosin
cyclin plus myosin
keratin plus actin
cyclin plus actin
92. Cytokinesis in plant cell mitosis occurs initially by the formation of a(n):
A.
B.
C.
D.
E.
aster.
mitotic spindle.
Golgi complex.
cell wall.
cell plate.
93. Generation time refers to:
A.
B.
C.
D.
E.
the number of years it takes for a generation to die.
the amount of time required to replicate the DNA in a cell.
the time it takes to complete one cell cycle.
the time required for an individual in a species to achieve sexual maturity.
None of the above.
94. If a cell is dividing by binary fission then you know that:
A.
B.
C.
D.
E.
mitosis has taken place without cytokinesis.
homologous chromosomes have already paired.
the cyclin-Cdk complex is no longer phosphorylating enzymes.
the cell cycle is out of control.
the cell is prokaryotic.
95. To prevent disastrous consequences, the eukaryotic cell cycle is controlled by:
A.
B.
C.
D.
E.
the mitochondria.
helper viruses.
environmental signals.
a very detailed, rigid genetic program.
a series of cell cycle checkpoints.
96. Which of the following statements concerning the cell cycle is FALSE?
A.
B.
C.
D.
E.
The activity of Cdks increases and decreases during the cell cycle.
Cyclins fluctuate during the cell cycle.
Cdks are active only when they bind to cyclins.
The anaphase-promoting complex stimulates the separation of sister chromatids
M-Cdk inhibits mitosis.
97. The correct number of chromosomes is maintained during sexual reproduction by:
A.
B.
C.
D.
E.
a process by which one half of the chromosomes in gametes are removed.
chromosome doubling in the newly formed zygote.
meiosis, which reduces the chromosome number by half.
mitosis, which maintains the original chromosome number.
replication of chromosomes twice during meiosis.
98. Animal cells are stimulated to divide by mitosis by:
A.
B.
C.
D.
E.
colchicines.
magnetic fields.
mating.
growth factors.
nutrients.
99. Chromatin fibers include
A.
DNA and structural polysaccharides
B.
RNA and phospholipids
C.
protein and carbohydrate
D.
DNA and protein
E.
triacylglycerol and steroids
100. A nucleosome consists of
A.
DNA and scaffolding proteins
B.
scaffolding proteins and histones
C.
DNA and histones
D.
DNA, histones, and scaffolding proteins
E.
histones only
101. The term S phase refers to
A.
DNA synthesis during interphase
B.
synthesis of chromosome proteins during prophase
C.
gametogenesis in animal cells
D.
synapsis of homologous chromosomes
E.
fusion of gametes in sexual reproduction
102. At which of the following stages do human skin cell nuclei have the same DNA content?
A.
early mitotic prophase and late mitotic telophase
B.
G1 and G2
C.
G1 and early mitotic prophase
D.
G1 and late mitotic telophase
E.
G2 and late mitotic telophase
103. In a cell at _____________, each chromosome consists of a pair of attached chromatids.
A.
mitotic prophase
B.
meiotic prophase II
C.
meiotic prophase I
D.
meiotic anaphase I
E.
all of the preceding
104. The molecular tether that links sister chromatids of a duplicated chromosome to each other is
A.
condensin
B.
actin
C.
myosin
D.
cohesion
E.
actomyosin
105. In an animal cell at mitotic metaphase, you would expect to find
A.
two pairs of centrioles located on the metaphase plate
B.
a pair of centrioles inside the nucleus
C.
a pair of centrioles within each microtubule-organizing center
D.
a centriole within each centromere
E.
no centrioles
106. In the spindle, the ___________ ends of kinetochore microtubules are embedded in the kinetochore, and the
___________ ends are at the spindle pole.
A.
plus; minus
B.
minus; plus
C.
plus; plus
D.
minus; minus
E.
none of these is correct
107. Cell plate formation usually begins during
A.
telophase in a plant cell
B.
telophase in an animal cell
C.
G2 in a plant cell
D.
G2 in an animal cell
E.
a and b
108. A particular plant species has a diploid chromosome number of 20. A haploid cell of that species at mitotic
prophase contains a total of ____________ chromosomes and __________ chromatids.
A.
20; 20
B.
20; 40
C.
10; 10
D.
10; 20
E.
none of the preceding, because haploid cells cannot undergo mitosis
109. A diploid nucleus at early mitotic prophase has ____________ set(s) of chromosomes; a diploid nucleus at
mitotic telophase has ____________ set(s) of chromosomes.
A.
1; 1
B.
1; 2
C.
2; 2
D.
2; 1
E.
not enough information has been given