Chapter 12 - Bio 1201
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) MPF C) protein kinase D) cyclin E) Cdk
E) Cdk
Which of the following describe(s) cyclin-dependent kinase (Cdk)? A) Cdk is inactive, or "turned off," in the presence of cyclin. B) Cdk is present throughout the cell cycle. C) Cdk is an enzyme that attaches phosphate groups to other proteins. D) Cdk is inactive, or "turned off," in the presence of cyclin and it is present throughout the cell cycle. E) Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins.
E) Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins.
For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable? A) It is safe enough to limit all apoptosis. B) It does not alter metabolically active cells. C) It only attacks cells that are density dependent. D) It interferes with cells entering G₀. E) It interferes with rapidly dividing cells.
E) It interferes with rapidly dividing cells.
The cyclin component of MPF is destroyed toward the end of which phase? A) G0 B) G1 C) S D) G2 E) M
E) M
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? A) The cell would prematurely enter anaphase. B) The cell would never leave metaphase. C) The cell would never enter metaphase. D) The cell would never enter prophase. E) The cell would undergo normal mitosis, but fail to enter the next G₁ phase.
E) The cell would undergo normal mitosis, but fail to enter the next G1 phase.
All cell cycle checkpoints are similar in which way? A) They respond to the same cyclins. B) They utilize the same Cdks. C) They give the go-ahead signal to progress to the next checkpoint. D) They each have only one cyclin/Cdk complex. E) They activate or inactivate other proteins.
E) They activate or inactivate other proteins.
Which of the following is true concerning cancer cells? A) They do not exhibit density-dependent inhibition when growing in culture. B) When they stop dividing, they do so at random points in the cell cycle. C) They are not subject to cell cycle controls. D) When they stop dividing, they do so at random points in the cell cycle, and they are not subject to cell cycle controls. E) 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; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B? A) spindle formation B) spindle attachment to kinetochores C) DNA synthesis D) cell elongation during anaphase E) cleavage furrow formation and cytokinesis
E) cleavage furrow formation of cytokinesis.
A biochemist measured the amount of DNA in cells growing laboratory and found that the quantity of DNA in cell doubled _______.
between G1 and G2 phases
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 30 D) 40 E) 80
A) 10
If there are 20 chromotids in a cell, how many centromeres are there? A) 10 B) 20 C) 30 D) 40 E) 80
A) 10
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) G1. B) G2. C) prophase. D) metaphase. E) anaphase.
A) G1.
Which of the following is released by platelets in the vicinity of an injury? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
A) PDGF
At the M phase checkpoint, the complex allows for what to occur? A) Separase enzyme cleaves cohesins and allows chromatids to separate. B) Cohesins alter separase to allow chromatids to separate. C) Kinetochores are able to bind to spindle microtubules. D) All microtubules are made to bind to kinetochores. E) Daughter cells are allowed to pass into G₁.
A) Separase enzyme cleaves cohesins and allows chromatids to separate.
The MPF protein complex turns itself off by A) activating a process that destroys cyclin components. B) activating an enzyme that stimulates cyclin. C) binding to chromatin. D) exiting the cell. E) activating the anaphase-promoting complex.
A) activating a process that destroys cyclin components
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in A) cells with more than one nucleus. B) cells that are unusually small. C) cells lacking nuclei. D) destruction of chromosomes. E) cell cycles lacking an S phase.
A) cells with more than one nucleus.
Which of the following triggers the cell's passage past the G2 checkpoint into mitosis? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
B) MPF
The centromere is a region in which A) chromatids remain attached to one another until anaphase B) metaphase chromosomes become aligned at the metaphase plate C) chromosomes are grouped during telophase D) the nucleus is located prior to mitosis E) new spindle microtubules form at either end
A) chromatids remain attached to one another until anaphase
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to A) disruption of mitotic spindle formation. B) inhibition of regulatory protein phosphorylation. C) suppression of cyclin production. D) myosin denaturation and inhibition of cleavage furrow formation. E) inhibition of DNA synthesis.
A) disruption of mitotic spindle formation.
Which of the following was a discovery that had to be made before human chromosomes could be correctly counted? A) how to use a hypotonic solution to swell nuclei B) how to visualize sperm nuclei C) how to visualize chromosomes D) when to see chromosomes separate from one another E) when to see chromosomes in pairs
A) how to use a hypotonic solution to swell nuclei
You have the technology necessary to measure each of the following in a sample of animal cell: chlorophylls, organelle density, picograms of DNA, cell wall, components, and enzymatic activity. Which would you expect to increase significantly from M to G1? A) organelle density and enzymatic activity B) cell wall components and DNA C) chlorophyll and cell walls D) organelle density and cell walls E) chlorophyll and DNA
A) organelle density and enzymatic activity
During which phase of mitosis do the chromatids become chromosomes? A) telophase B) anaphase C) prophase D) metaphase E) cytokinesis
A) telophase
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) the formation of mitotic spindle. B) anaphase C) formation of the centrioles. D) chromatid assembly. E) the S phase of cell cycle.
A) the formation of mitotic spindle.
Assume that you are dealing with a species in which the number of chromosomes in each somatic cell is 14. How many sister chromatids are present in the early telophase of mitosis? A. 0 B. 28 C. 7 D. 14 E. None of the listed responses is correct.
A. 0
Down syndrome is characterized by cells having three copies of chromosome 21. As a cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present? A. 94 B. 98 C. 92 D. 46 E. 23
A. 94
Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle? A. G1 B. cytokinesis C. G2 D. M E. S
A. G1
The phase of mitosis during which the chromosomes move toward separate poles of the cell is ______. A. anaphase B. metaphase C. telophase D. prophase E. prometaphase
A. anaphase
The function of the mitotic cell cycle is to produce daughter cells that ________. A. are genetically identical to the parent cell (assuming no mutation has occurred) B. have the same number of chromosomes as the parent cell but not the same genetic content C. have the same number of chromatids as the parent cell had chromosomes D. have a random assortment of maternal and paternal chromosomes E. None of the listed responses is correct.
A. are genetically identical to the parent cell (assuming no mutation has occurred)
In animal cell mitosis, the cleavage furrow forms during which stage of cell cycle? A. cytokinesis B. prophase C. anaphase D. the G1 phase E. metaphase
A. cytokinesis
"Cytokinesis" refers to ________. A. division of the cytoplasm B. movement of a cell from one place to another C. division of the entire cell D. division of the nucleus E. reduction in the number of chromosomes
A. division of the cytoplasm
You would know a dividing cell was a plant cell rather than an animal cell if you saw that _____. A. it had formed a cell plate B. it had two pairs of centrioles during prophase C. the nucleolus was visible during metaphase D. it had microtubules E. it had formed a cleavage furrow
A. it had formed a cell plate
At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell? A. metaphase B. interphase C. anaphase D. telophase E. prophase
A. metaphase
In a human skin cell that is going through the cell cycle, when do the centrosomes seperate? A. prophase B. S phase C. metaphase D. G2 phase E. anaphase
A. prophase
During binary fission in bacterium _____. A. the origins of replication move apart B. the two DNA molecules divide in half, forming four DNA fragments C. the two DNA molecules attach to the centrioles D. the two DNA molecules float free in the cell and are guided to daughter cells by a spindle-like apparatus E. the two DNA molecules break up into plasmids
A. the origins of replication move apart
Following cytokinesis in animal cells, how many centrioles does each new daughter cell possess? A. two B. one C. eight D. zero E. four
A. two
Density-dependent inhibition is explained by which of the following? A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors. B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing. C) 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. D) As cells become more numerous, more and more of them enter the S phase of the cell cycle. E) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.
B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.
For a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission? A) Binary fission would not allow for the formation of new organism. B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes. C) Cell division would be faster than binary fission. D) Cell division allows for lower rates of error per chromosome replication. E) Binary fission would not allow the organism to have complex cells.
B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes.
After which checkpoint is the cell first committed to continue the cell cycle through M? A) G0 B) G1 C) G2 D) S E) previous M
B) G1
Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells? A) kinetochores B) Golgi-derived vesicles C) actin and myosin D) centrioles and centromeres E) cyclin-dependent kinases
B) Golgi-derived vesicles
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 process of cytokinesis. B) a plant cell in the process of cytokinesis. C) an animal cell in the S phase of the cell cycle. D) a bacterial cell dividing. E) a plant cell in metaphase.
B) a plant cell in the process of cytokinesis.
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? A) centromere B) centrosome C) centriole D) chromatid E) kinectochore
B) centrosome
Which of the following does not occur during mitosis? A) condensation of the chromosomes B) replication of the DNA C) separation of sister chromatids D) spindle formation E) separation of the spindle poles
B) replication of the DNA
What explains anchorage dependence of animal cells in vitro or in vivo? A) attachment of spindle fibers to centrioles B) response of the plasma membrane to cell cycle controls C) the makeup of the extracellular matrix of the substrate D) the binding of cell-surface phospholipids to those of adjoining cells E) the binding of cell-surface phospholipids to the substrate
B) response of the plasma membrane to cell cycle controls
Why do chromosomes coil during mitosis? A) to increase their potential energy B) to allow the chromosomes to move without becoming the entangled and breaking C) to allow the chromosomes to fit within the nuclear envelope D) to allow the sister chromatids to remain attached E) to provide for the structure of the centromere
B) to allow the chromosomes to move without becoming entangled and breaking
How many maternal chromosomes are present in a somatic human cell not engaged in cell division? A. 46 B. 23 C. 184 D. 92 E. None of the listed responses is correct.
B. 23
If a somatic human cell is just about to divide, it has ______ chromatids. A. 0 B. 92 C. There is insufficient information to answer the question. D. 46 E. 23
B. 92
Which of the following correctly matches a phase of the cell cycle with its description? A. G2: cell division B. G1: follows cell division C. M: duplication of DNA D. S: immediately precedes cell division E. All of the above are correctly matched
B. G1: follows cell division
Which of the following is true to benign tumors, but not malignant tumors? A. They migrate from the initial site of transformation to other organs or tissues. B. They remain confined to their original site. C. They are the result of the transformation of normal cells. D. They have an unusual number of chromosomes. E. They can divide indefinitely if an adequate supply of nutrients is available.
B. They remain confined to their original site.
Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division? A. formation of the mitotic spindle B. cleavage C. DNA replication D. binary fission E. formation of the cell plate
B. cleavage
Tissue culture experiments with PDGF demonstrate that without this substance _______. A. bacterial cells lose their resistance to antibiotics B. fibroblasts fail to divide C. the various kinases, such as MPF, are unable to bind to cyclin D. animal cells are unable to attach to the substratum E. cells divide in an uncontrolled fashion, confirming PDGF's role as a cell division inhibitor
B. fibroblasts fail to divide
You would be unlikely to see which of the following human cells dividing? A. cell from an embryo B. nerve cell C. cancer cell D. skin cell E. intestinal lining cell
B. nerve cell
In telophase of mitosis, the mitotic spindle breaks down ant the chromatin uncoils. This is essentially the opposite of what happens in ________. A. S phase B. prophase C. metaphase D. anaphase E. interphase
B. prophase
Which of the following does NOT occur during mitosis? A. alignment of chromosomes along the cell's equator B. replication of chromosomes C. condensation of chromatin D. separation of chromatids E. the movement of chromosomes to opposite poles
B. replication of chromosomes
DNA replication occurs in ______. A. the G1 phase of interphase in reproductive cells only B. the S phase of interphase in both somatic and reproductive cells C. the cytokinesis portion of the cell's life cycle D. metaphase of meiosis only E. prophase of both mitosis and meiosis
B. the S phase of interphase in both somatic and reproductive cells
One event occurring during prophase is _______. A. the alignment of chromosomes in a single plane B. the beginning of the formation of a spindle apparatus C. the synthesis of a new nuclear envelope D. division of the centromere E. cytokinesis
B. the beginning of the formation of spindle apparatus
Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur? A) Cancer cells are no longer density dependent. B) Cancer cells are no longer anchorage dependent. C) Chromosomally abnormal cells can still go through cell cycle checkpoints. D) Chromosomally abnormal cells still have normal metabolism. E) Transformation introduces new chromosomes into cells.
C) Chromosomally abnormal cells can still go through cell cycle checkpoints.
For anaphase to begin, which of the following must occur? A) Chromatids must lose their kinetochores. B) Cohesin must attach the sister chromatids to each other. C) Cohesin must be cleaved enzymatically. D) Kinetochores must attach to the metaphase plate. E) Spindle microtubules must begin to depolymerize.
C) Cohesin must be cleaved enzymatically.
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) Find out which ones have a higher rate of apoptosis. C) Karyotype samples to look for unusual size and number of chromosomes. D) Measure metastasis. E) Time their cell cycles.
C) Karyotype samples to look for unusual size and number of chromosomes.
A particular cyclin called cyclin E forms a complex with Cdk 2 (cyclin-dependent kinase 2). This complex is important for the progression of the cell from G₁ into the S phase of the cell cycle. Which of the following statements is correct? A) The amount of free cyclin E is greatest during the S phase. B) The amount of free Cdk 2 is greater during G₁ compared to the S phase. C) The amount of free cyclin E is highest during G₁. D) The amount of free Cdk 2 is greatest during G₁. E) The activity of the cyclin E/Cdk 2 complex is highest during G₂.
C) The amount of free cyclin E is highest during G1.
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 cells would immediately die. B) The cells would be unable to begin M and stay in G₂. C) The chromosomes would coil and shorten but have no spindle to which to attach. D) The chromosomes would segregate but in a disorderly pattern. E) Each resultant daughter cell would also be unable to form a spindle.
C) The chromosomes would coil and shorten but have no spindle to which to attach.
Why do neurons and some other specialized cells divide infrequently? A) They no longer have active nuclei. B) They no longer carry receptors for signal molecules. C) They have been shunted into G0. D) They can no longer bind Cdk to cyclin. E) They show a drop in MPF concentration.
C) They have been shunted into G0.
What is a cleavage furrow? A) a ring of vesicles forming a cell plate B) the separation of divided prokaryotes C) a groove in the plasma membrane between daughter nuclei D) the metaphase plate where chromosomes attach to the spindle E) the space that is created between two chromatids during anaphase
C) a groove in the plasma membrane between daughter nuclei
One difference between cancer cells and normal cells is that cancer cells A) are unable to synthesize DNA. B) are arrested at the S phase of the cell cycle. C) continue to divide even when they are tightly packed together. D) cannot function properly because they are affected by density-dependent inhibition. E) are always in the M phase of the cell cycle.
C) continue to divide even when they are tightly packed together.
Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor? A) metastasis B) changes in the order of cell cycle stages C) lack of appropriate cell death D) inability to form spindles E) inability of chromosomes to meet at the metaphase plate
C) lack of appropriate cell death
The decline of MPF activity at the end of mitosis is due to A) the destruction of the protein kinase Cdk. B) decreased synthesis of Cdk. C) the degradation of cyclin. D) the accumulation of cyclin. E) synthesis of DNA.
C) the degradation of cyclin
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? A. 46 B. 23 or 46, depending on the portion of prophase examined C. 92 D. 46 or 92, depending on the portion of prophase examined E. 23
C. 92
Which of the following is found in binary fission but not in mitosis? A. Following the process, a membrane separates the 2 copies. B. Replication of DNA begins at an origin. C. Duplicated chromosomes attach to the plasma membrane. D. Replicated strands of DNA separate. E. The result produces 2 nuclei.
C. Duplicated chromosomes attach to the plasma membrane
During what phase in the cell cycle would you find the most DNA per cell? A. prophase II B. S C. G2 D. S1 E. G1
C. G2
The region of a chromosome holding the two double strands of replicated DNA together is cell _________. A. a centriole B. an aster C. a centromere D. chromatin E. a chromatid
C. a centromere
During which stage of cell cycle do sister chromatids separate? A. prophase B. G1 phase C. anaphase D. G2 phase E. metaphase
C. anaphase
During interphase, the genetic material of typical eukaryotic cell is ________. A. dispersed in the cytoplasm as long strands of chromatin B. transported through the nuclear pores C. dispersed in the nucleus as long strands of chromatin D. condensed and the chromosomes are often visible under the light microscope E. attached to microtubule spindle fibers
C. dispersed in the nucleus as long strands of chromatin
Observation of cancer cells in culture support the hypothesis that cancer cells ______. A. spend the majority of their time in the G0 phase B. exhibit anchorage dependence C. do not exhibit density-dependent inhibition D. produce molecules that inhibit the growth factors required for cell division E. All of the listed responses are correct.
C. do not exhibit density-dependent inhibiton
Which of the following represents a mismatch or incorrect description? A. anaphase: there is movement of the chromosomes to the poles B. telophase: chromosomes become more extended C. metaphase: the nuclear envelope disappears D. metaphase: chromosomes line up on the equatorial plane E. prophase: chromosomes become more tightly coiled
C. metaphase: the nuclear envelope disappears
The centromere is the region in which _________. A. the new cell plate forms in telophase B.chromosomes become aligned during metaphase C. sister chromatids are attached to one another in prophase D. the chromosomes are connected to the cell plate in metaphase E. microtubules are fastened to the centrioles during anaphase
C. sister chromatids are attached attach to one another in prophase
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measure 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) G0 B) G1 C) S D) G2 E) M
D)
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) 8; 8 B) 8; 16 C) 16;8 D) 16; 16 E) 12; 16
D) 16; 16
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? A) 4 B) 8 C) 16 D) 32 E) 64
D) 32
Which of the following is (are) required for motor proteins to function in the movement of chromosomes toward the poles of the mitotic spindle? A) intact centromeres B) an MTOC (microtubule organizing center) C) a kinetochore attached to the metaphase plate D) ATP as an energy source E) synthesis of cohesin
D) ATP as an energy source
Which of the following most accurately describes a cyclin? A) It is present in similar concentrations throughout the cell cycle. B) It is activated to phosphorylate by complexing with a Cdk. C) It decreases in concentration when MPF activity increases. D) It activates a Cdk molecule when it is in sufficient concentration. E) It activates a Cdk when its concentration is decreased.
D) It activates a Cdk molecule when it is in sufficient concentration.
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) The cells originated in the nervous system. B) The cells are unable to form spindle microtubules. C) They have altered series of cell cycle phases. D) The cells show characteristics of tumors. E) They were originally derived from an elderly organism.
D) The cells show characteristics of tumors.
Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis? A) The chromosomes are "reeled in" by the contraction of spindle microtubules. B) Motor proteins of the kinetochores move the chromosomes along the spindle microtubules. C) Nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles. D) The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules. E) The chromosomes are "reeled in" by the contraction of spindle microtubules, motor proteins of the kinetochores move the chromosomes along the spindle microtubules, and nonkinetichore spindle fibers serve to push chromosomes in the direction of the poles.
D) The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules.
Which of the following proteins are involved in binary fission as well as eukaryotic mitotic division? A) cyclins B) Cdks C) MPF D) actin and tubulin E) cohesins
D) actin and tubulin
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) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
D) cyclin
In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis? A) seedless plants B) dinoflagellates C) diatoms D) dinoflagellates and diatoms only E) seedless plants, dinoflagellates, and diatoms
D) dinoflagellates and diatoms only
What causes the decrease in the amount of cyclin at a specific point in the cell cycle? A) an increase in production once the restriction point is passed B) the cascade of increased production once its protein is phosphorylated by Cdk C) the changing ratio of cytoplasm to genome D) its destruction by a process initiated by the activity of its complex with a cyclin E) the binding of PDGF to receptors on the cell surface
D) its destruction by a process initiated by the activity of its complex with a cyclin
Which of the following is a function of those spindle microtubules that do not attach to the kinetochores? A) maintaining an appropriate spacing among the moving chromosomes B) producing a cleavage furrow when telophase is complete C) providing the ATP needed by the fibers attached to kinetochores D) maintaining the region of overlap of microtubules in the cell's center E) pulling the poles of the spindles closer to one another
D) maintaining the region of overlap of microtubules in the cell's center
If cells in the processs of dividing are subjected to colchicine, a drug that interferes with formation of the spindle apparatus, at which stage will mitosis be arrested? A) anaphase B) prophase C) telophase D) metaphase E) interphase
D) metaphase
Movement of the chromosomes during anaphase would be most affected by a drug that A) reduces cyclin concentrations. B) increases cyclin concentrations. C) prevents elongation of microtubules. D) prevents shortening of mictrotubules. E) prevents attachment of the microtubules to the kinetochore.
D) prevents shortening of microtubules.
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) fluorescence microscopy B) electron microscopy C) spectrophotometry D) radioactive-labeled nucleotides E) labeled kinetochore proteins
D) radioactive-labeled nucleotides
Suppose a biologist can separate one of a dozen pieces of chromotin from a eukaryotic (animal) nucleus. It might consist of which of the following? A) one-twelfth of the genes of the organism B) two chromosomes, each with six chromatids C) a single circular piece of DNA D) two long strands of DNA plus proteins E) two chromatids attached together at a centromere
D) two long strands of DNA plus proteins
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; 8 B. 12; 16 C. 8; 8 D. 16; 16 E. 8;16
D. 16;16
What is the difference between a benign tumor and malignant tumor? A. Benign tumors arise by transformation; malignant tumors do not. B. Benign tumors do not arise by transformation; malignant tumors do. C. Cells of benign tumors metastasize; those of malignant tumors do not. D. Cells of benign tumors do not metastasize; those of malignant tumors do. E. Benign tumors will not kill you; malignant tumors will.
D. Cells of benign tumors do not metasize; those of malignant tumors do not.
When a cell in S phase is fused with a cell in G1, _______. A. the replication of DNA occurring in the original S nucleus is terminated B. the two nuclei fuse and further division is arrested C. the original G1 cell will divide immediately D. DNA synthesis begins immediately in the original G1 nucleus E. the chromosomes of the original G1 nucleus condense in preparation for mitosis
D. DNA synthesis begins immediately in the original G1 nucleus
Which of the following triggers the cell's passage past the G2 checkpoint into mitosis? A. PDGF B. Cdk C. protein kinase D. MPF E. cyclin
D. MPF
The person credited with first recognizing (in the 1860s) that living cells cannot arise spontaneously, but arise only from previously existing cells, is ____________. A. Watson B. Anton van Leeuwenhoek C. Louis Pasteur D. Rudolf Virchow E. Robert Hooke
D. Rudolf Virchow
Which of the following is true about kinectochores? A. They are the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis. B. They interdigitate at the cell's equator and then move apart, causing the cell to elongate. C. They attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow. D. They are sites at which microtubules attach to chromosomes. E. They are located at the center of the centrosome; their function is to organize tubulin into elongated bundles called spindle fibers.
D. They are sites at which microtubules attach to chromosomes.
Why is it difficult to observe individual chromosomes with a light microscope during interphase? A. They leave the nucleus and are disperse to other parts of the cell. B. The spindle must move them to the metaphase paste before they become visible. C. Sister chromatids do not pair up until division starts. D. They have uncoiled to form long, then strands. E. The DNA has not yet been replicated.
D. They have uncoiled to form long, then strands.
Chromatids are _______. A. composed of RNA B. the bacterial equivalent of eukaryotic chromosomes C. held together by the centrioles D. identical copies of each other if they are part of the same chromosome E. found only in aberrant chromosomes
D. identical copies of each if they are part of the same chromosome
Which of the following processes does NOT occur in dividing bacteria? A. binary fission B. separation of the origins of replication C. replication of DNA D. mitosis E. inward growth of the plasma membrane
D. mitosis
Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope? A. anaphase B. S phase C. metaphase D. telophase E. interphase
D. telophase
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called he cell cycle, are called A) ATPases. B) kinetochores. C) kinases. D) proton pumps. E) cyclins.
E) cyclins.
At which phase are centrioles beginning to move apart in animal cells? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase
E) prophase
If a cell contain chromatids at the start of mitosis, how many chromosome will be found in each daughter cell at the completion of the cell cycle? A. 15 B. 60 C. 45 D. 120 E. 30
E, 30
A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA at G1 of the cell cycle in one of the grasshopper daughter cells? A. 400 units B. between 50 and 100 units C. 200 unites D. 50 units E. 100 units
E. 100 units
Which event or events occur during anaphase? A. identical chromatids move to opposite poles B. the centrioles are at opposite poles C. the centromeres divide D. a spindle made of microtubules is present E. All of the listed responses are correct.
E. All the listed responses are correct.
Which of the following is false regarding sister chromatids? A. Sister chromatids are attached to one another at the centromere. B. Sister chromatids form in the S-phase stage of the cell cycle. C. Sister chromatids are created when DNA is replicated. D. Sister chromatids are separated during mitosis. E. Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.
E. Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred.
The complex of DNA and protein that makes up eukaryotic chromosome is properly called _________. A. a chromoplast B. a chromatid C. a centrosome D. a centromere E. chromatin
E. chromatin
Which of the following is involved in binary fission of bacteria? A. prophase, prometaphase, metaphase, anaphase, and telophase B. disintegration of the nuclear membrane C. formation of a spindle apparatus D. formation of a cell plate E. distribution of a copy of the single parental chromosome to each daughter cell
E. distribution of a copy of the single parental chromosome to each daughter cell
In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this? A. a decrease in chromosome number B. inability to duplicate DNA C. a rapid rate of gamete production D. division of the organism into many cells, most lacking nuclei E. large cells containing many nuclei
E. large cells containing many nuclei
A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with ______. A. 64 chromosomes B. 16 chromosomes C. 32 pairs of chromosomes D. 64 pairs of chromosomes E. None of the listed responses is correct.
None of the listed responses is correct.
