Chapter 12: The Cell Cycle

What causes the rhythmic change in cyclin concentration in the cell cycle?
1. an increase in production once the restriction point is passed.
2. the cascade of increased production once its enzyme is phosphorylated by cdc2
3. the changing ration of cytoplasm to genome
4. its destruction by an enzyme phosphorylated by MPF
5. the binding of PDGF to receptors on the cell surface
A cell that passes the restriction point will most likely
1. move into prophase of mitosis.
2. undergo chromosome duplication.
3. stop dividing.
4. show a drop in MPF concentration.
5. have just completed cytokinesis to separate into two new cells.
Which of the following organisms does NOT reproduce cells by mitosis and cytokinesis?
1. cow
2. bacterium
3. mushroom
4. cockroach
5. banana tree
Cytokinesis usually, but not always, follows mitosis. If cells undergo mitosis and not cytokinesis, this would result in
1. a cell with a single large nucleus.
2. a cell with two or more nuclei.
3. cells with abnormally small nuclei.
4. feedback responses that prevent mitosis.
5. death of the cell line.
If there are 12 chromosomes in an animal cell in the G1 stage of the cell cycle, what is the diploid number of chromosomes for this organism?
1. 6
2. 12
3. 24
4. 36
5. 48
Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants
1. the spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils.
2. sister chromatids are identical, but they differ from one another in animals.
3. a cell plate begins to form at telophase, whereas, in animals a cleavage furrow is initiated at that stage
4. chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase.
5. spindle poles contain centrioles, whereas spindle poles in animals do not.
How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?
1. The daughter cells have half the amount of cytoplasm and half the amount of DNA.
2. The daughter cells have half the number of chromosomes and half the amount of DNA.
3. The daughter cells have the same number of chromosomes and half the amount of DNA.
4. The daughter cells have the same number of chromosomes and the same amount of DNA.
5. The daughter cells have the same number of chromosomes and twice the amount of DNA.
Cells that have stopped dividing and are differentiating are
1. cancer cells.
2. in the G2 phase of the cell cycle.
3. in the G1 phase of the cell cycle.
4. in the S phase of the cell cycle.
5. in the M phase of the cell cycle.
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. One nucleus had 5 picograms of DNA. What stage of the cell cycle was this nucleus in?
1. G0
2. G1
3. S
4. G2
5. M
Which of the following is released by platelets in the vicinity of an injury?
1. PDGF
2. MPF
3. protein kinase
4. cyclin
5. cdc2
Which of the following is a family of enzymes that catalyzes the transfer of phosphate group from ATP to target proteins
1. PDGF
2. MPF
3. protein kinase
4. cyclin
5. cdc2
Fibroblasts have receptors for which of the following substances on their plasma membranes?
1. PDGF
2. MPF
3. protein kinase
4. cyclin
5. cdc2
Which of the following is a substance synthesized through the cell cycle that accumulates during early interphase and associates with another protein to form active enzymes.
1. PDGF
2. MPF
3. protein kinase
4. cyclin
5. cdc2
Which of the following triggers the activation of numerous proteins that facilitate mitosis?
1. PDGF
2. MPF
3. protein kinase
4. cyclin
5. cdc2
Which of the following contains the "restriction point"?
1. G0
2. G1
3. S
4. G2
5. M
Nerve and muscle cells are in which of the following phases.
1. G0
2. G1
3. S
4. G2
5. M
Which of the following is the shortest part of the cycle?
1. G0
2. G1
3. S
4. G2
5. M
In which of the following are chromosomes duplicated?
1. G0
2. G1
3. S
4. G2
5. M
In which of the following is cyclin destroyed toward to the end of the phase?
1. G0
2. G1
3. S
4. G2
5. M
The formation of a cell plate is beginning across the middle of a cell and nuclei are re-forming at opposite ends of the cell. What kind of a cell is this?
1. an animal cell in metaphase
2. an animal cell in telophase
3. an animal cell undergoing cytokinesis
4. a plant cell in metaphase
5. a plant cell undergoing cytokinesis
In which of the following phases are two centrosomes arranged at opposite poles of the cell.
1. telophase
2. anaphase
3. prometaphase
4. metaphase
5. prophase
In which of the following phases do the centrioles begin to move apart in animal cells?
1. telophase
2. anaphase
3. prometaphase
4. metaphase
5. prophase
In which of the following phases is the longest of the mitotic stages?
1. telophase
2. anaphase
3. prometaphase
4. metaphase
5. prophase
In which of the following phases, do the centromeres uncouple, sister chromatids separate and the two new chromosomes move to opposite poles of the cell?
1. telophase
2. anaphase
3. prometaphase
4. metaphase
5. prophase
The centromere is a region in which
1. chromatids are attached to one another.
2. metaphase chromosomes become aligned.
3. chromosomes are grouped during telophase.
4. the nucleus is located prior to mitosis.
5. new spindle microtubules form
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested?
1. anaphase
2. prophase
3. telophase
4. metaphase
5. interphase
All of the following are characteristics of telophase of mitosis EXCEPT:
1. Cytokinesis begins.
2. Each chromosome is made of two chromatids.
3. The nuclear envelope reappears.
4. Chromosomes begin to uncoil.
5. Astral microtubules disappear.
A cell containing 92 chromatids at the start of mitosis would, at its completion, produce cells containing how many chromosomes?
1. 12
2. 16
3. 23
4. 46
5. 92
During which phase(s) of mitosis do we find chromosomes composed of two chromatids?
1. from interphase through anaphase.
2. from G1 of interphase through metaphase
3. from metaphase through telophase
4. from anaphase through telophase
5. from G2 of interphase through metaphase
If there are 20 centromeres in a cell, how many chromosomes are there?
1. 10
2. 20
3. 30
4. 40
5. 80
All of the following occur during the latter stages of mitotic prophase EXCEPT:
1. The centrioles move apart.
2. The nucleolus disintegrates.
3. The nuclear envelope disappears.
4. Chromosomes are duplicated.
5. The spindle is organized.
If there are twelve centromeres in a cell in G1 of the cell cycle, what is the diploid number of chromosomes?
1. 6
2. 12
3. 24
4. 36
5. 48
If the haploid number for a species is 3, each dividing diploid cell will have how many chromatids at metaphase?
1. 3
2. 6
3. 9
4. 12
5. 18
All of the following occur during mitosis EXCEPT
1. the coiling of chromosomes
2. the division of centromeres
3. the formation of a spindle
4. the synthesis of DNA
5. the degradation of the nuclear envelope
How many chromosomes will a cell have during mitotic anaphase if the diploid chromosome number is 4?
1. 1
2. 2
3. 4
4. 8
5. 16
MPF reaches its threshold concentration at the end of this stage.
1. I
2. II
3. III
4. IV
5. V
The restriction point occurs at the end of this phase.
1. I and V
2. II and IV
3. III only
4. IV only
5. V only
Enzymes that control the activities of other proteins are called
1. ATPases
2. microtubules
3. kinetochores
4. chromatin
5. protein kinases
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called
1. ATPases
2. kinetochores
3. centrioles
4. proton pumps
5. cyclins
The MPF protein complex turns itself off by
1. activating an enzyme that destroys cyclin.
2. activating an enzyme that stimulates cyclin.
3. binding to chromatin.
4. exiting the cell.
5. None of these is true; MPF is always active.
Recent research has indicated that cancer cells
1. transform normal cells by altering genes involved in the control of mitosis
2. always develop into a tumor.
3. contain more than the normal number of chromosomes.
4. are unable to complete the cell cycle after the S phase.
5. enter and exit the G0 phase three times before they divide.
Colchicine is a drug that binds to protein that forms microtubules, thereby preventing microtubules from forming. Colchicine has been used to study mitosis because it stops the process. Most likely this is due to
1. prevention of sister chromatid formation.
2. prevention of kinetochore formation.
3. inhibition of DNA synthesis.
4. alteration of centriole structure.
5. prevention of cell-plate formation.
Which of the following is NOT true of the bacterial chromosome? It
1. contains a single, circular DNA molecule.
2. is associated with proteins.
3. floats freely inside the bacterial cell.
4. is highly folded within the cell.
5. has genes that control binary fission.
A cell with 20 chromosomes (diploid number) goes through the cell cycle. The number of chromosomes after doubling the DNA in the S phase is
1. 20
2. 40
3. 10
4. called the S number of chromosomes.
5. called haploid
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
1. the fibers of the mitotic spindle.
2. anaphase.
3. formation of the centrioles.
4. chromatid assembly.
5. the S phase of the cell cycle.
A cell is just beginning the S phase of the cell cycle. It is fused to a cell in metaphase of mitosis. Which of the following best describes what would happen to the nucleus of the first cell?
1. It would stop DNA synthesis and immediately divide, with essentially no G2.
2. It would continue to complete S, have a short G2, and then divide.
3. It would stop DNA synthesis, undergo a relatively normal G2, and then divide.
4. It would continue to complete S, have a normal G2, and then divide.
5. It would immediately stop S and enter G0
Which of the following is NOT analogous to the "checkpoints" that control cell division?
1. the "checkpoints" at a military base that control the movement of people in and out of the base.
2. the use of a magnetic reader to verify a credit card.
3. the use of a user ID and password to access a computer account.
4. the use of a telephone number to call home
5. the use of a PIN to get money from an ATM
As the cell progresses through prophase and into metaphase, the level of active anaphase-promoting complex proteins.
1. increases gradually.
2. decreases gradually
3. is initially zero and increases sharply once all the chromosomes are lined up in metaphase
4. is initially high, but drops precipitously when all the chromosomes are lined up in metaphase.
5. remains constant
A mutation results in a cell that no longer produces a normal protein kinase for the M-phase checkpoint. Which of the following would likely be the immediate result of this mutation?
1. The cell would prematurely enter anaphase.
2. The cell would never leave metaphase.
3. The cell would never enter metaphase.
4. The cell would never enter prophase.
5. The cell would undergo normal mitosis, but fail to enter the next G1.
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. Those cells would have _______ picograms at the end of the S phase and _______ picograms at the end of G2.
1. 8, 8
2. 8, 16
3. 16, 8
4. 16, 16
5. 12, 16
Which of the following events must take place before the spindle fibers can attach to the kinetochore?
1. destruction of cyclin
2. synthesis of cyclin
3. breakdown of the nuclear membrane
4. separation of the chromatids
5. movement of the chromosomes to the metaphase plate
The drug chloral hydrate prevents elongation of microtubules by preventing the addition of new subunits to the growing end. During which stage of mitosis would chloral hydrate be most harmful?
1. prophase
2. metaphase
3. anaphase
4. telophase
5. none of these is correct
Movement of the chromosomes during anaphase would be most affected by a drug that
1. reduced cyclin concentrations.
2. increased cyclin concentrations.
3. prevented elongation of microtubules.
4. prevented shortening of microtubules
5. prevented attachment of the microtubules to the kinetochore.