Biology Cell Cycle

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Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely
A. an animal cell in the S phase of the cell cycle.
B. a bacterial cell dividing.
C. an animal cell in the process of cytokinesis.
D. a plant cell in the process of cytokinesis.
E. a plant cell in metaphase.

D

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of micro-tubules, its effectiveness must be related to
A. suppression of cyclin production.
B. myosin denaturation and inhibition of cleavage furrow formation.
C. disruption of mitotic spindle formation.
D. inhibition of DNA synthesis.
E. inhibition of regulatory protein phosphorylation.

C

One difference between cancer cells and normal cells is that cancer cells
A. cannot function properly because they are affected by density-dependent inhibition.
B. continue to divide even when they are tightly packed together.
C. are always in the M phase of the cell cycle.
D. are arrested at the S phase of the cell cycle.
E. are unable to synthesize DNA.

B

The decline of MPF activity at the end of mitosis is due to
A.the accumulation of cyclin.
B. decreased synthesis of Cdk.
C. the destruction of the protein kinase Cdk.
D. synthesis of DNA.
E. the degradation of cyclin.

E

In the cells of some organisms, mitosis occurs without cytoki-nesis. This will result in
A. cell cycles lacking an S phase.
B. cells lacking nuclei.
C. cells that are unusually small.
D. destruction of chromosomes.
E. cells with more than one nucleus.

E

Which of the following does not occur during mitosis?
A. spindle formation
B. separation of sister chromatids
C. condensation of the chromosomes
D. replication of the DNA
E. separation of the spindle poles

D

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in
A. metaphase.
B. prophase.
C. G1.
D. anaphase.
E.G2.

C

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?
A. spindle attachment to kinetochores
B. spindle formation
C. cell elongation during anaphase
D. DNA synthesis
E cleavage furrow formation and cytokinesis

E

What is true of all cancers?
A. They are inherited.
B. They have escaped normal cell cycle controls.
C. They are caused by chemical carcinogens.

B

The cell cycle control systems of cancer cells differ from those of normal cells. Select the best explanation for this fact.
A. Cancer cells divide excessively and invade other tissues.
B. Genetic changes alter the function of the cancer cell's protein products.
C. Cancer cells are immortal.

B

If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct?
A. Each chromosome consists of two identical chromatids.
B. The chromosomes are preparing for DNA synthesis.
C. Each chromosome is made of a complex of DNA and associated proteins.

C

Which statement provides the best description of the interphase portion of the cell cycle?
A. During interphase, a cell is metabolically active.
B. Interphase is a resting stage prior to cell division.
C. Interphase is a brief period between mitosis and chromosome duplication.

A

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
A. 64
B. 4
C. 8
D. 16
E. 32

E

If there are 20 chromatids in a cell, how many centromeres are there?
A. 20
B. 30
C. 40
D. 80
E. 10

A

At which phase are centrioles beginning to move apart in animal cells?
A. telophase
B. anaphase
C. prometaphase
D. prophase
E. metaphase

D

How do cancer cells differ from normal cells?
A.Cultured cancer cells exhibit anchorage dependence.
B. Cancer cells trigger chromosomal changes in surrounding cells.
C. Cancer cells may be immortal.

C

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?
A. 40
B. 10
C. 80
D. 20
E. 30

B

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?
A. S
B. G2
C. M
D. G1
E. G0

B

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?
A.16; 16
B. 12; 16
C. 16; 8
D. 8; 16
E. 8; 8

A

The beginning of anaphase is indicated by which of the following?
A. Spindle microtubules begin to polymerize.
B. Kinetochores attach to the metaphase plate.
C. Chromatids lose their kinetochores.
D. Cohesin is cleaved enzymatically.
E. Cohesin attaches the sister chromatids to each other.

D

What is a cleavage furrow?
A. a ring of vesicles forming a cell plate
B. the separation of divided prokaryotes
C. the metaphase plate where chromosomes attach to the spindle
D. the space that is created between two chromatids during anaphase
E. a groove in the plasma membrane between daughter nuclei

E

Using which of the following techniques would enable your lab group to distinguish between a cell in G2 and a cell from the same organism in G1?
A. labeled kinetochore proteins
B. electron microscopy
C. fluorescence microscopy
D. radioactive-labeled nucleotides
E. spectrophotometry

D

You have the technology necessary to measure each of the following in a sample of animal cells: chlorophylls, organelle density, picograms of DNA, cell wall components, and enzymatic activity. Which would you expect to increase significantly from M to G1?
A. chlorophyll and DNA
B. organelle density and enzymatic activity
C. chlorophyll and cell walls
D. organelle density and cell walls
E cell wall components and DNA

B

A plant-derived protein known as colchicine can be used to poison cells by blocking the formation of the spindle. Which of the following would result if colchicine is added to a sample of cells in G2?
A. The chromosomes would segregate but in a disorderly pattern.
B. The cells would be unable to begin M and stay in G2.
C. Each resultant daughter cell would also be unable to form a spindle.
D. The chromosomes would coil and shorten but have no spindle to which to attach.
E. The cells would immediately die.

D

The lettered circle in the figure shows a diploid nucleus with four chromosomes. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is symbolized as black and the other haploid set is gray. The chromosomes in the unlettered circle have not yet replicated. Choose the correct chromosomal conditions for the following stages.
What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis?
A
B
C
D
E

E

If the cell whose nuclear material is shown in the figure continues toward completion of mitosis, which of the following events would occur next?
A. formation of telophase nuclei
B. synthesis of chromatids
C. nuclear envelope breakdown
D. spindle fiber formation
E. cell membrane synthesis

A

In the figure above, mitosis is represented by which numbered part(s) of the cycle?
A. I
B. II
C. III
D. IV
E. V

D

G1 is represented by which numbered part(s) of the cycle?
A. I or V
B. II or IV
C. III only
D. IV only
E. V only

A

The data were obtained from a study of the length of time spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma.
Of the following, the best conclusion concerning the difference between the S phases for beta and gamma is that
A. beta and gamma contain the same amount of DNA.
B. gamma contains 48 times more DNA and RNA than beta.
C. gamma contains more DNA than beta. D. beta cells reproduce asexually.
E. beta is a plant cell and gamma is an animal cell.

C

The data were obtained from a study of the length of time spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma.The best conclusion concerning delta is that the cells
A. contain no RNA.
B. contain only one chromosome that is very short.
C. contain no DNA.
D. divide in the G1 phase.
E. are actually in the G0 phase.

E

Several organisms, primarily protists, have what are called intermediate mitotic organization.These protists are intermediate in what sense?
A. They maintain a nuclear envelope during division.
B. They use mitotic division but only have circular chromosomes.
C. They reproduce by binary fission in their early stages of development and by mitosis when they are mature.
D. They never coil up their chromosomes when they are dividing.
E. None of them form spindles.

A

Several organisms, primarily protists, have what are called intermediate mitotic organization.What is the most probable hypothesis about these intermediate forms of cell division?
A. They demonstrate that these species are not closely related to any of the other protists and may well be a different kingdom.
B. They may be more closely related to plant forms that also have unusual mitosis.
C. They represent a form of cell reproduction which must have evolved completely separately from those of other organisms.
D. They rely on totally different proteins for the processes they undergo.
E. They show some but not all of the evolutionary steps toward complete mitosis.

E

Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.
Which of the following question might be answered by such a method?
A. When is the S chromosome synthesized?
B. How many cells are produced by the culture per hour?
C. When do spindle fibers attach to chromosomes?
D. What is the length of the S phase of the cell cycle?
E. How many picograms of DNA are made per cell cycle?

D

Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.
The research team used the setup to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that
A. the presence of the pathogen made the experiment too contaminated to trust the results.
B. infection causes cell cultures in general to reproduce more rapidly.
C. infection causes lymphocyte cultures to skip some parts of the cell cycle.
D. their tissue culture methods needed to be relearned.
E. infection causes lymphocytes to divide more rapidly.

E

Where do the microtubules of the spindle originate during mitosis in animal cells?
A. centriole
B. kinetochore
C. centrosome
D. centromere
E. chromatid

C

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect
A. chromatid assembly.
B. the S phase of the cell cycle.
C. formation of the centrioles.
D. anaphase.
E. the formation of the mitotic spindle.

E

Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?
A. tubulin and dynein
B. actin and myosin
C. centrioles and centromeres
D. Golgi-derived vesicles
E. kinetochores

D

Movement of the chromosomes during anaphase would be most affected by a drug that prevents
A. formation of a cleavage furrow.
B. elongation of microtubules.
C. nuclear envelope breakdown.
D. cell wall formation.
E. shortening of microtubules.

E

During which phase of mitosis do the chromatids become chromosomes?
A. metaphase
B. anaphase
C. cytokinesis
D. prophase
E. telophase

B

Cells from advanced malignant tumors often have very abnormal chromosomes as well as an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?
A. Chromosomally abnormal cells still have normal metabolism.
B. Cancer cells are no longer density dependent.
C. Cancer cells are no longer anchorage dependent.
D. Transformation introduces new chromosomes into cells.
E. Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.

E

Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle?
A. intact centromeres
B. synthesis of cohesin
C. a kinetochore attached to the metaphase plate
D. a microtubule-organizing center
E. ATP as an energy source

E

When a cell is in late anaphase of mitosis, which of the following will he see?
A. individual chromatids beginning to separate from one another
B. chromosomes clustered at the poles
C. a clear area in the center of the cell
D. chromosomes clustered tightly at the center
E. breaking down of the nuclear envelope

C

Which of the following is released by platelets in the vicinity of an injury?
A. protein kinase
B. MPF
C. PDGF
D. Cdk
E. cyclin

C

Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?
A. protein kinase
B. cyclin
C. PDGF
D. Cdk
E. MPF

B

Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?
A. PDGF
B. Cdk
C. cyclin
D. protein kinase
E. MPF

B

Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?
A. MPF
B. Cdk
C. protein kinase
D. PDGF
E. cyclin

A

The cyclin component of MPF is destroyed toward the end of which phase?
A. G1
B. M
C.S
D. G2
E. G0

B

The MPF protein complex turns itself off by
A. binding to chromatin.
B. exiting the cell.
C. activating a process that destroys cyclin components.
D activating the anaphase-promoting complex.
E. activating an enzyme that stimulates cyclin.

C

Density-dependent inhibition is explained by which of the following?
A. As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.
B. As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors.
C. As cells become more numerous, more and more of them enter the S phase of the cell cycle.
D. As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor.
E. As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.

E

Which of the following is true concerning cancer cells?
A. They are not subject to cell cycle controls.
B. They do not exhibit density-dependent inhibition when growing in culture.
C. When they stop dividing, they do so at random points in the cell cycle, and they are not subject to cell cycle controls.
D. When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.
E. When they stop dividing, they do so at random points in the cell cycle.

D

Which of the following describe(s) cyclin-dependent kinase (Cdk)?
A. Cdk is inactive, or "turned off," in the presence of cyclin and it is present throughout the cell cycle.
B. Cdk is an enzyme that attaches phosphate groups to other proteins.
C. Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins.
D. Cdk is present throughout the cell cycle.
E. Cdk is inactive, or "turned off," in the presence of cyclin.

C

Why do neurons and some other specialized cells divide infrequently?
A. They show a drop in MPF concentration.
B. They no longer carry receptors for signal molecules.
C. They no longer have active nuclei.
D. They can no longer bind Cdk to cyclin.
E. They have been shunted into G0.

E

Which of the following most accurately describes a cyclin?
A. It is present in similar concentrations throughout the cell cycle.
B. It activates a Cdk molecule when it is in sufficient concentration.
C. It is activated to phosphorylate by complexing with a Cdk.
D. It activates a Cdk when its concentration is decreased.
E. It decreases in concentration when MPF activity increases.

B

At the M phase checkpoint, the complex allows for what to occur?
A. Daughter cells are allowed to pass into G1.
B. Cohesins alter separase to allow chromatids to separate.
C. All microtubules are made to bind to kinetochores.
D. Separase enzyme cleaves cohesins and allows chromatids to separate.
E. Kinetochores are able to bind to spindle microtubules.

D

A research team began a study of a cultured cell line. Their preliminary observations showed them that the cell line did not exhibit either density-dependent inhibition or anchorage dependence. What could they conclude right away?
A. They were originally derived from an elderly organism.
B. The cells originated in the nervous system.
C. The cells are unable to form spindle microtubules.
D. The cells show characteristics of tumors.
E. They have altered series of cell cycle phases.

D

For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable?
A. It interferes with rapidly dividing cells.
B. It only attacks cells that are density dependent.
C. It interferes with cells entering G0.
D. It does not alter metabolically active cells.
E. It is safe enough to limit all apoptosis.

A

You have a series of cells, all of which were derived from tumors, and you first need to find out which ones are malignant. What could you do?
A. See which ones are not overproliferating.
B. Karyotype samples to look for unusual size and number of chromosomes.
C. Measure metastasis.
D. Find out which ones have a higher rate of apoptosis.
E. Time their cell cycles.

B

Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called
A. cyclins.
B. ATPases.
C. kinetochores.
D. kinases.
E. estrogen receptors.

A

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?
A. enhanced anchorage dependence
B. lack of appropriate cell death
C. changes in the order of cell cycle stages
D. inability to form spindles
E. inability of chromosomes to meet at the metaphase plate

B

All cell cycle checkpoints are similar in which way?
A. They give the go-ahead signal to progress to the next checkpoint.
B. They each have only one cyclin/Cdk complex.
C. They activate or inactivate other proteins.
D. They utilize the same Cdks.
E. They respond to the same cyclins.

A

Anchorage dependence of animal cells in vitro or in vivo depends on which of the following?
A. response of the cell cycle controls to signals from the plasma membrane
B. the binding of cell-surface phospholipids to those of adjoining cells
C. the binding of cell-surface phospholipids to the substrate
D. the absence of an extracellular matrix
E. attachment of spindle fibers to centrioles

A

Which is the first checkpoint in the cell cycle where a cell will be caused to exit the cycle if this point is not passed?
A. previous M
B. G2
C. G0
D. G1
E. S

D

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