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molec cell > Cell Cycle > Flashcards

Cell Cycle Flashcards

1
Q
  1. The eukaryotic cell cycle is composed of four phases in the following order:
    a. G1; G2; S; M.
    b. G1; S; G2; M.
    c. G1; M; G2; S.
    d. S; G1; G2; M.
    e. S; G1; M; G2
A

b. G1; S; G2; M.

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2
Q
  1. The length of time it takes for the cells labeled during DNA synthesis to begin to enter
    mitosis is a good estimate of the length of the _______ phase(s).
    a. G1
    b. S
    c. G2
    d. M
    e. S and G2
A

a. G1

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3
Q
  1. In a typical cycling mammalian cell, _______ of the cell cycle is spent in interphase.
    a. 99%
    b. 95%
    c. 75%
    d. 50%
    e. 25%
A

b. 95%

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4
Q
  1. Cell cycles of early embryonic animal cells are unusual because they have
    a. no G1.
    b. no G2.
    c. a short S.
    d. All of the above
    e. None of the above
A

d. All of the above

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5
Q
  1. The number of cells in the different phases of a population can be determined most
    easily by measuring the amount of DNA per cell in a large sample of cells with a
    a. scintillation counter.
    b. flow cytometer.
    c. fluorescence microscope.
    d. phase-contrast microscope after autoradiography.
    e. absorption spectrophotometer
A

b. flow cytometer.

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6
Q
  1. Cells in the quiescent phase of the cell cycle are said to be in the _______ phase.
    a. G1
    b. G0
    c. G2
    d. M
    e. S
A

b. G0

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7
Q
  1. Which of the following represents the amount of DNA in a typical G2 cell?
    a. n
    b. 2n
    c. 4n
    d. 8n
    e. 16n
A

c. 4n

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8
Q
  1. The G1 checkpoint in budding yeast cells is called
    a. START
    b. the restriction point.
    c. the decision point.
    d. the G1/S boundary.
    e. None of the above; yeast have no G1.
A

a. START

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9
Q
  1. The G1 checkpoint in animal cells is called
    a. START.
    b. the restriction point.
    c. the decision point.
    d. the G1/S boundary.
    e. None of the above; the animal cell checkpoint is in G2
A

b. the restriction point.

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10
Q 
10. Skin fibroblasts arrested in G0 are stimulated near a wound to enter G1 by \_\_\_\_\_\_\_
growth factor.
a. epidermal
b. platelet-derived
c. fibroblast
d. keratinocyte
e. epithelial
A

b. platelet-derived

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11
Q
  1. The G2 checkpoint prevents entry into _______ if _______.
    a. G2; DNA synthesis is not complete
    b. M; DNA synthesis is not complete
    c. M; DNA is damaged
    d. Both b and c
    e. All of the above
A

d. Both b and c

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12
Q 
12. Cells are restricted to one round of DNA replication per cycle by origin of replication
binding proteins called
a. ATMs.
b. Akts.
c. Oris.
d. MCMs.
e. Histone H5
A

d. MCMs.

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13
Q
  1. Maturation promotion factor (MFP), discovered by Masui and Markert, is the factor
    that
    a. was missing in the cdc2 mutant in yeast.
    b. induced entry into meiosis when injected into frog oocytes.
    c. fluctuated in amount during early cleavages of sea urchin eggs.
    d. fluctuated in amount during the cell cycle of mammalian cells.
    e. allowed cells to pass start.
A

b. induced entry into meiosis when injected into frog oocytes.

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14
Q
  1. MPF is a
    a. monomeric protein kinase.
    b. dimer of two molecules of Cdk1.
    c. dimer of Cdk1 and cyclin A.
    d. dimer of Cdk1 and cyclin B.
    e. dimer of Cdk1 and cyclin D
A

d. dimer of Cdk1 and cyclin B.

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15
Q
  1. MPF is a general regulator of the transition from
    a. G1 to S.
    b. S to G2.
    c. G2 to M.
    d. metaphase to anaphase.
    e. M to G1.
A

c. G2 to M.

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16
Q 
16. Studies on cell cycle mutants in budding and fission yeasts demonstrated that cdc2
and cdc28 both encode a
a. cyclin.
b. protein kinase.
c. protein phosphatase.
d. ubiquinating enzyme.
e. growth factor.
A

b. protein kinase.

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17
Q
  1. Two sea urchin proteins were named cyclin A and B because, during the embryonic
    cell cycle, they were periodically
    a. activated and inactivated by phosphorylation and dephosphorylation.
    b. synthesized and degraded.
    c. bound and released by another protein.
    d. None of the above
    e. All of the above
A

b. synthesized and degraded.

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18
Q
  1. If a mutation is induced in the yeast gene for Wee1, progeny cells will likely
    a. be larger than normal.
    b. be smaller than normal.
    c. fail to divide.
    d. divide more slowly than normal.
    e. None of the above
A

c. fail to divide.

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19
Q
  1. To become active, Cdk1 must
    a. bind cyclin.
    b. bind cyclin and be phosphorylated on tyrosine 15 and threonines 14 and 161.
    c. bind cyclin and be phosphorylated on tyrosine 15, and be dephosphorylated on
    threonines 14 and 161.
    d. bind cyclin and be phosphorylated on threonine 161, and be dephosphorylated on
    threonine 14 and tyrosine 15.
    e. be phosphorylated on threonine 161, be dephosphorylated on threonine 14 and tyrosine
    15, and then bind to cyclin.
A

b. bind cyclin and be phosphorylated on tyrosine 15 and threonines 14 and 161.

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20
Q
  1. In addition to binding cyclin, Cdks are activated by
    a. phosphorylation by Wee1.
    b. dephosphorylation by Cdc25 protein phosphatase.
    c. binding of Ink4.
    d. binding of Cip.
    e. binding of p21.
A

a. phosphorylation by Wee1

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21
Q
  1. Which cyclin(s) are required to pass the G1 restriction point in animal cells?
    a. Cyclin A
    b. Cyclin B
    c. Cyclin D
    d. Cyclin E
    e. Cyclins D and E
A

e. Cyclins D and E

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22
Q
  1. Passage of animal cells through the cell cycle is regulated primarily by
    a. the availability of nutrients.
    b. intracellular second messengers.
    c. extracellular growth factors.
    d. direct cell surface interactions.
    e. steroid hormones.
A

c. extracellular growth factors.

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23
Q
  1. The retinoblastoma protein (Rb) binds to and inhibits
    a. oncogenes.
    b. transcription factor E2F.
    c. cyclin-dependent kinase.
    d. p53.
    e. cyckin D.
A

a. oncogenes.

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24
Q 
24. Growth-factor stimulation of the Ras/Raf/ERK pathway initially stimulates the
synthesis of cyclin
a. A.
b. B.
c. C.
d. D.
e. E.
A

d. D.

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25
Q
  1. Damaged DNA is sensed by a complex of proteins that activate the protein kinase
    a. ATM or ATR.
    b. ABS.
    c. Akt.
    d. MCM.
    e. p53.
A

a. ATM or ATR.

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26
Q 
26. The disease ataxia telangiectasia, which causes nervous system defects and a high
frequency of cancer in affected individuals, results from a mutation in the gene for the
protein
a. ATM.
b. ABS.
c. Akt.
d. MCM.
e. ATG.
A

a. ATM.

27
Q
  1. To prevent cells with unreplicated DNA from passing through the G2 checkpoint,
    CHK1 and CHK2 _______ and _______ protein phosphatase Cdc25.
    a. phosphorylate; stimulate
    b. phosphorylate; inhibit
    c. dephosphorylate; stimulate
    d. dephosphorylate; inhibit
    e. dephosphorylate; induce the degradation of
A

b. phosphorylate; inhibit

28
Q
  1. p21 inhibits cell cycle progression by binding to and inhibiting
    a. cyclin-dependent kinases.
    b. p53.
    c. ATM.
    d. Rb protein.
    e. Both a and b
A

a. cyclin-dependent kinases.

29
Q
  1. Nuclear envelope breakdown occurs at the _______ of _______.
    a. beginning; prophase
    b. end; prophase
    c. end; prometaphase
    d. end; metaphase
    e. beginning; anaphase
A

b. end; prophase

30
Q
  1. Entry into mitosis occurs because
    a. cyclin is destroyed at the beginning of mitosis.
    b. cyclin is phosphorylated at the beginning of mitosis.
    c. sufficient cyclin-dependent kinase is synthesized to trigger mitosis.
    d. cyclin binds to a protein kinase and activates it.
    e. Both b and c
A

e. Both b and c

31
Q
  1. During prophase, MPF directly phosphorylates
    a. condensins
    b. lamins.
    c. microtubule-associated proteins.
    d. All of the above
    e. None of the above
A

a. condensins

32
Q
  1. Phosphorylation of the Golgi proteins GM130 and GRASP-65 by Cdk1
    a. inhibits vesicle docking and fusion.
    b. causes degradation of these proteins.
    c. activates these proteins to degrade the Golgi proteins.
    d. inhibits association of the Golgi with microtubules.
    e. causes microtubules to pull the Golgi in two.
A

a. inhibits vesicle docking and fusion.

33
Q
  1. Chromosomes are attached to spindle microtubules by
    a. centromeres.
    b. kinetochores.
    c. centrioles.
    d. centrosomes.
    e. kinetosomes.
A

b. kinetochores.

34
Q
  1. Polar microtubules
    a. are attached to the spindle poles.
    b. overlap in the center of the spindle.
    c. are attached to kinetochores.
    d. pull kinetochores poleward.
    e. Both a and b
A

e. Both a and b

35
Q
  1. During mitosis, the rate of microtubule turnover
    a. decreases.
    b. stays the same.
    c. doubles.
    d. increases five- to tenfold.
    e. increases five- to ten percent.
A

d. increases five- to tenfold.

36
Q 
37. The beginning of anaphase occurs when cohesins holding the sister chromatids
together are degraded by
a. anaphase-promoting complexes.
b. ATMs.
c. proteasomes.
d. separases.
e. ubiquitins
A

e. ubiquitins

37
Q
  1. Meiosis differs from mitosis in that meiosis
    a. involves two cell divisions.
    b. produces haploid cells from diploid cells.
    c. has a longer prophase.
    d. Both a and b
    e. All of the above
A

d. Both a and b

38
Q 
39. The structure that associates homologous chromosomes during meiotic prophase is
called a
a. chiasma.
b. synaptonemal complex.
c. centromere.
d. homolog.
e. pachytene complex.
A

b. synaptonemal complex.

39
Q
  1. In addition to the independent assortment of chromosomes at anaphase, the diversity
    of haploid daughter cells is increased by the process of
    a. somatic mutation.
    b. crossing over and recombination.
    c. chromosome elimination.
    d. selection of the fittest sperm.
    e. fertilization of the fittest egg
A

b. crossing over and recombination.

40
Q
  1. For how long can human oocytes remain arrested in diplotene?
    a. One month
    b. Nine months
    c. Ten years
    d. Fifty years
    e. Oocytes do not arrest in diplotene
A

d. Fifty years

41
Q 
43. When a Xenopus oocyte is stimulated with the hormone progesterone, it enters
meiosis and arrests at
a. prophase I.
b. metaphase I.
c. interphase I.
d. prophase II.
e. metaphase II.
A

e. metaphase II.

42
Q
  1. The cytostatic factor that holds the oocytes at the arrest point is called
    a. Fos.
    b. Mos.
    c. Kos.
    d. Boss.
    e. MPF
A

b. Mos.

43
Q
  1. Fertilization of a frog egg triggers the resumption of meiosis by an increase in
    a. ATP.
    b. Ca2+
    c. cAMP.
    d. PIP2.
    e. MPF.
A

b. Ca2+

44
Q
  1. Fertilization by multiple sperm is blocked by
    a. exocytosis of cortical granules.
    b. hardening of the plasma membrane.
    c. hyperpolarization of the plasma membrane.
    d. release of spermicidal jelly.
    e. All of the above
A

a. exocytosis of cortical granules.

45
Q
  1. A fertilized egg is called a(n)
    a. oocyte.
    b. zygote.
    c. blastula.
    d. embryo.
    e. polar body
A

b. zygote.

46
Q
  1. Interphase is defined as
    a. the G1 and G2 phases.
    b. the G1, G2, and S phases.
    c. G0, the quiescent phase.
    d. M phase
A

b. the G1, G2, and S phases.

47
Q 
2. The phase of cell cycle that corresponds to the interval between mitosis and initiation
of DNA replication is referred to as the
a. M phase.
b. S phase.
c. G1 phase.
d. G2 phase
A

c. G1 phase.

48
Q
  1. In which of the following cell types do G1 and G2 not take place?
    a. Early embryonic cells
    b. Budding yeast cells
    c. Typical proliferating human cells
    d. Skin fibroblasts
A

a. Early embryonic cells

49
Q
  1. DNA content can be determined using a method of flow cytometry that can determine
    2n or 4n states of cells based on cell counting and fluorescent labeling of DNA. Which of
    the following phases would be identified through flow cytometry as 2n?
    a. M phase
    b. S phase
    c. G2 phase
    d. G1 phase
A

d. G1 phase

50
Q 
6. In yeast, START triggers the progression from G1 to S. Which of the following are
involved in regulating START?
a. Nutrients
b. Mating factors
c. Cell size
d. All of the above
A

d. All of the above

51
Q 
7. In the absence of growth factor, most animal cells will stop cell cycle at a restriction
point in what stage?
a. S phase
b. M phase
c. G2 phase
d. G1 phase
A

d. G1 phase

52
Q
  1. Most cells in an adult animal are
    a. in G0, or quiescent, phase.
    b. actively proliferating.
    c. stem cells.
    d. undergoing meiosis.
A

a. in G0, or quiescent, phase.

53
Q
  1. Cell cycle checkpoints ensure that complete genomes are transmitted to daughter cells.
    DNA damage checkpoints are found in which of the following phases of the cell cycle?
    a. G1 phase
    b. S phase
    c. G2 phase
    d. All of the above
A

d. All of the above

54
Q
  1. The G2 cell cycle checkpoint detects
    a. the binding of the MCM proteins to origins of replication.
    b. chromosome misalignment.
    c. unreplicated or damaged DNA.
    d. levels of p53.
A

c. unreplicated or damaged DNA

55
Q
  1. Which of the following statements about cyclin B is false?
    a. It is a component of MPF.
    b. It accumulates throughout S and G2.
    c. It activates Cdc2 protein kinase.
    d. It cycles between active and inactive states in the cell cycle.
A

c. It activates Cdc2 protein kinase.

56
Q
  1. The p21 and p15 proteins are examples of
    a. Cdk inhibitors.
    b. cyclins.
    c. oncogenes.
    d. growth factors.
A

a. Cdk inhibitors.

57
Q
  1. Which of the following is not one of the phases of mitosis?
    a. Prophase
    b. S phase
    c. Metaphase
    d. Anaphase
A

b. S phase

58
Q 
15. The sequence of DNA on each chromosome where the sister chromatids are held
together is called the
a. centrosome.
b. kinetochore.
.c. centromere
d. centriole.
A

.c. centromere

59
Q 
16. Which of the following are not phosphorylated by the Cdk1/cyclin B complex during
mitosis?
a. Condensins
b. Golgi matrix proteins
c. Nuclear lamins
d. Histone H3
A

d. Histone H3

60
Q
  1. The progression from metaphase to anaphase is triggered by
    a. activation of protein kinases by MPF.
    b. ubiquitin-mediated proteolysis of key proteins.
    c. binding of an inhibitory protein to MPF.
    d. depolymerization of the mitotic spindle.
A

b. ubiquitin-mediated proteolysis of key proteins.

61
Q 
18. During what phase of meiosis does recombination between maternal and paternal
chromosomes occur?
a. Anaphase I
b. S phase
c. Prophase II
d. Prophase I
A

d. Prophase I

62
Q
  1. Which of the following is not involved in metaphase II arrest during meiosis?
    a. Cytostatic factor (CSF)
    b. Mos
    c. Rsk
    d. An increase in cytoplasmic calcium levels
A

c. Rsk

63
Q
  1. At fertilization, the sperm binds to a receptor on the surface of the egg and fuses with
    the plasma membrane, initiating the development of a new diploid organism. Which of
    the following statements in reference to fertilization is true?
    a. Binding of a sperm to its receptor on the egg induces an increase in cytoplasmic
    calcium.
    b. Once fertilized, secretory vesicles are exocytosed, leading to an alteration in the
    extracellular coat of the egg to prevent additional sperm entry.
    c. Eggs are arrested at metaphase II of meiosis and fertilization leads to anaphase
    progression.
    d. All of the above
A

d. All of the above

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