Cell Division Cycle - Quiz 3

The region of a chromosome to which the microtubules of the mitotic spindle attach, via the kinetochore, during cell division is called__________. a) centromere b) centrosome c) chromatid d) cohesin

a) centromere

The principal microtubule-organizing center in animal cells is the a) centrosome. b) centromere. c) kinetochore. d) cell cortex.

a) centrosome.

Which of the following does not occur during M phase in animal cells? a) growth of the cell b) condensation of chromosomes c) breakdown of nuclear envelope d) attachment of chromosomes to microtubules

a) growth of the cell

Sister chromatid separation occurs because __________ are destroyed by the APC/C. a) securins b) cohesins c) kinetochores d) condensins

a) securins

Is the following statement TRUE or FALSE? The concentration of M-Cdk varies in a cyclical fashion during the cell cycle. It peaks at the beginning of the M phase. M-Cdk is degraded via the ubiquitin-proteasome pathway around anaphase, which results in the exit of M phase. a) True b) False

b) False

The M-cyclin/M-Cdk complex triggers entry into M phase, while the S-cyclin/S-Cdk complex sets the stage for the exit of mitosis. a) True b) False

b) False

Which of the following events does NOT usually occur during interphase? a) Cells grow in size. b) The nuclear envelope breaks down. c) DNA is replicated. d) The centrosomes are duplicated.

b) The nuclear envelope breaks down.

Progression through the cell cycle requires a cyclin to bind to a Cdk because a) the cyclins are the molecules with the enzymatic activity in the complex. b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity. c) cyclin binding inhibits Cdk activity until the appropriate time in the cell cycle. d) without cyclin binding, a cell-cycle checkpoint will be activated.

b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity.

The anaphase-promoting complex or cyclosome (APC/C) is a) E1 ubiquitin-activating enzyme b) E2 ubiquitin-conjugating enzyme c) E3 ubiquitin ligase d) Deubiquitinase

c) E3 ubiquitin ligase

Which of the following statements about the anaphase-promoting complex (APC) is FALSE? a) It promotes the degradation of proteins that regulate M phase. b) It inhibits M-Cdk activity. c) It is continuously active throughout the cell cycle. d) M-Cdk stimulates its activity.

c) It is continuously active throughout the cell cycle.

Cohesins are cleaved by separases at__________. a) metaphase b) prophase c) anaphase d) prometaphase

c) anaphase

At the end of DNA replication, the sister chromatids are held together by the a) kinetochores. b) securins. c) cohesins. d) histones.

c) cohesins.

Which of the following statements about the drugs colchicine and Taxol® is True? a) Colchicine and Taxol® are used to treat human cancers because they cause mitotic defects b) Colchicine and Taxol® disrupt the segregation of the chromosomes during mitosis c) Colchicine and Taxol® disrupt the attachments of the mitotic spindle to kinetochores. d) All of the above

d) All of the above

Which of the following statements about the spindle checkpoint is TRUE? a) The spindle checkpoint is a checkpoint at the metaphase-to-anaphase transition b) The spindle checkpoint prevents the separation of the duplicated chromosomes until each chromosome is properly attached to the spindle c) The spindle checkpoint sends a "stop" signal by the kinetochore of any unattached chromosome and inhibits APC/C d) All of the above

d) All of the above

Which stage of mitosis does this fluorescence micrograph show? image shows microtubules (green) spread out throughout the cell and chromosomes (red) separated and close to the center of the two cells. a) Prophase b) Prometaphase c) Metaphase d) Anaphase

d) Anaphase

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? a) The cell would be unable to enter M phase. b) The cell would be unable to enter G2. d) The cell would enter M phase under conditions when normal cells would not. e) The cell would pass through M phase more slowly than normal cells.

d) The cell would enter M phase under conditions when normal cells would not.

What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only? a) The cells would not be able to replicate their DNA. b) The mitotic spindle could not assemble. c) The cells would get larger and larger. d) The cells produced would get smaller and smaller.

d) The cells produced would get smaller and smaller.

Which of the following statements is TRUE? a) The mitotic spindle is largely made of intermediate filaments. b) The contractile ring is made largely of microtubules and actin filaments. c) The contractile ring divides the nucleus in two. d) The mitotic spindle helps segregate the chromosomes to the two daughter cells.

d) The mitotic spindle helps segregate the chromosomes to the two daughter cells.

In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated? a) at the transition between G1 and S b) when cells enter G0 c) during M d) at the end of G2

d) at the end of G2

Which word or phrase below best describes the phase in mitosis depicted in this figure? drawing of microtubules attached to chromosomes that are still together and at the center between the two forming cells. a) anaphase b) prometaphase c) S-phase checkpoint d) metaphase

d) metaphase --> duh, the chromosomes are at the metaphase plate