Chapter 12 [Mitosis, Cell Cycle, Cancer]

In which phase of the cell cycle do cells replicate their DNA?

S phase

In what cell cycle phases do cells have double the DNA content of G1 phase?

-S phase

-G2 phase

-The beginning of M phase

A replicated chromosome...

Contains two centromeres

Which of the following is a structure that contains the microtubule organizing complex in an animal cell?

Centrosome

What type of microtubules attach to chromosomes?

Kinetochore microtubules

Which of the following correctly matches the phase of mitosis with an event that happens in that phase?

Prometaphase: nuclear envelope breaks down

Which of the following correctly matches a stage of M phase with an event that occurs during it?

Anaphase: sister chromatids are pulled apart

Why are chromosomes pulled apart in anaphase?

Kinetochore microtubules depolymerize

In this experiment, the injection of cytosol from an interphase cell served as...

a negative control

Which of the following is TRUE about MPF?

-CDK activity is regulated by phosphorylation and cyclin-binding

-MPF is made up of two protein components

Which of the following is true about MPF activity in the cell cycle?

-The peak of active MPF Cdk occurs during M phase

-MPF cyclin is rapidly degraded soon after M phase begins

True or false? All cyclins follow the same pattern of expression over time in the cell cycle.

False

Which of the following can be triggered by protein phosphorylation of MPF Cdk?

-Chromatin condensation

-Breakdown of the nuclear envelope (nuclear membrane)

-Fragmentation of Golgi Apparatus

-Spindle Formation

Which of the following statements about cell cycle checkpoints is incorrect?

Cells do not enter S phase without confirmation of successful DNA replication

True or False? All types of cancers have a failure of cell cycle checkpoints.

True

Which of the following is true about social control of the G1 checkpoint?

-E2F increases expression of S phase genes

-Activated G1 Cdk phosphorylates Rb

Q//What do you think? Which component of the G1 checkpoint pathway would be a good target for HPV to inhibit and why?

HPV also uses its E7 protein to inactivate Rb. Normally, Rb prevents the cell from entering S phase by keeping the transcription factor E2F inactive. When HPV disables Rb, E2F is released, causing the cell to enter S phase prematurely.

HPV would target p53 because p53 normally stops the cell cycle when DNA is damaged. By disabling p53, HPV prevents the G₁ checkpoint from halting cell division. This pushes the cell into S phase, giving the virus access to the host's DNA replication machinery.

What checkpoints does p53 help regulate?

-G1/S

-G2/M