A relatively good estimate of the length of the _______ phase(s) may be obtained by
determining how long it takes for the cells labeled during DNA synthesis to start to enter
mitosis.
a. G1
b. S
c. G2
d. M Answer c G2
For a typical cycling mammalian cell, _______ of the cell cycle is spent in interphase.
a. 99%
b. 95%
c. 75%
d. 50% Answer b. 95%
The relative number of cells in the different phases of a population can be most easily
determined by
using a _______ to measure the amount of DNA per cell in a large sample of cells.
a. scintillation counter
b. flow cytometer
c. fluorescence microscope
d. phase-contrast microscope after autoradiography - Answer b. flow cytometer
Which one of the following represents the amount of DNA in a typical G2 cell?
a. n
b. 2n
,c. 4n
d. 8n - Answer c. 4n
The G1 checkpoint in budding yeast cells is called
a. START
b. the restriction point
c. the decision point
d. the G1/S boundary - Answer a. START
The G1 checkpoint in animal cells is called
a. START
b. the restriction point
c. the decision point
d. the G1/S boundary - Answer b. the restriction point
Skin fibroblasts arrested in G0 are stimulated near a wound to enter G1 by _______
growth
factor.
a. epidermal
b. fibroblast
c. platelet-derived
d. keratinocyte - Answer c. platelet-derived
The G2 checkpoint prevents entry into _______ if _______.
a. G1; DNA synthesis is not complete and/or DNA is damaged
b. S; DNA synthesis is not complete and/or DNA is damaged
c. G2; DNA synthesis is not complete and/or DNA is damaged
,d. M; DNA synthesis is not complete and/or DNA is damaged - Answer d. M; DNA
synthesis is not complete and/or DNA is damaged
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 - Answer d. dimer of Cdk1 and cyclin B
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 - Answer c. G2 to M
In order 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 Answer d. bind cyclin and be phosphorylated on threonine 161, and be
dephosphorylated on threonine 14
and tyrosine 15
Cdks bind to cyclin and are activated by:
a. phosphorylation by Wee1
, b. dephosphorylation by Cdc25 protein phosphatase
c. the binding of Ink4
d. the binding of Cip
Answer b. dephosphorylation by Cdc25 protein phosphatase
The retinoblastoma protein (Rb) binds to and inhibits:
a. transcription factor E2F
b. oncogenes
c. cyclin-dependent kinase
d. p53
Answer a. transcription factor E2F
Polar microtubules:
a. overlap in the center of the spindle
b. are attached to the contractile ring
c. are bound to kinetochores
d. pull kinetochores poleward - Answer a. interdigitate at the center of the spindle
The rate of microtubule turnover during mitosis:
a. slows
b. remains the same
c. doubles
d. increases five- to tenfold - Answer d. increases five- to tenfold
The start of anaphase is initiated when cohesins holding sister chromatids together are
degraded by:
a. anaphase promoting complex
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