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Molecular Cell Biology Jessica > Chapter 17 Study Questions > Flashcards

Chapter 17 Study Questions 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 
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.	]
f.	S and G2
A

c. G2

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3
Q

. 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

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

. 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. (or fluorescence activated cell sorter)
c. fluorescence microscope.
d. phase-contrast microscope after autoradiography.
e. absorption spectrophotometer

A

b. flow cytometer. (or fluorescence activated cell sorter)

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6
Q

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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7
Q

. 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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8
Q

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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9
Q

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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10
Q

. 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

A

d. Both b and c

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11
Q

. 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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12
Q

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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13
Q

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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14
Q

. 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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15
Q

. 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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16
Q

. 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

d. bind cyclin and be phosphorylated on threonine 161, and be dephosphorylated on threonine 14 and tyrosine 15.

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17
Q

. 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

b. dephosphorylation by Cdc25 protein phosphatase.

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18
Q

. 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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19
Q

The retinoblastoma protein (Rb) binds to and inhibits

a. oncogenes.
b. transcription factor E2F.
c. cyclin-dependent kinase.
d. p53.
e. cyckin D.

A

b. transcription factor E2F.

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20
Q

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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21
Q

. 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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22
Q

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.

23
Q

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

24
Q

. 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.

25
Q

. 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

26
Q

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.

A

d. cyclin binds to a protein kinase and activates it.

27
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

d. All of the above

28
Q
  1. Chromosomes are attached to spindle microtubules by
    a. centromeres.
    b. kinetochores.
    c. centrioles.
    d. centrosomes.
    e. kinetosomes
A

b. kinetochores.

29
Q

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

30
Q

. 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

e. All of the above

31
Q

. 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.

32
Q

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.

33
Q

. In meiosis I, sister chromatids

a. go to opposite poles.
b. go to the same poles.
c. have kinetochores facing in opposite directions.
d. synapse with each other during the zygotene stage.
e. Both a and c

A

b. go to the same poles.

34
Q

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

35
Q

. 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.

36
Q

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.

37
Q

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.

38
Q

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

39
Q 
. 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

40
Q

. 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

41
Q

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

42
Q

. 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.

43
Q

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

44
Q

. 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.

45
Q

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.

46
Q

. The p21 and p15 proteins are examples of

a. Cdk inhibitors.
b. cyclins.
c. oncogenes.
d. growth factors

A

a. Cdk inhibitors.

47
Q

. Which of the following statements regarding cyclin D1 is false?

a. It is required for cell cycle progression.
b. It is activated by growth factors.
c. It is rapidly degraded following removal of appropriate growth factors.
d. It is always present and its activity is regulated by fluctuating levels of Cdk4 and Cdk6. Textbook Reference

A

d. It is always present and its activity is regulated by fluctuating levels of Cdk4 and Cdk6. Textbook Reference:

48
Q

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

49
Q
  1. The sequence of DNA on each chromosome where the sister chromatids are held together is called the
A

c. centromere.

50
Q

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

51
Q

. 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.

52
Q

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

53
Q

. 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. An increase in cytoplasmic calcium levels

Molecular Cell Biology Jessica (33 decks)

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