Chapter 12

Which of these phases encompasses all of the stages of mitosis?

E

Which of the following correctly matches a phase of the cell cycle with its description? Hint 1. The S stage occurs between G1 and G2.

G1 follows cell division.

During ___ the cell grows and replicates both its organelles and its chromosomes.

Interphase

For a chemotherapeutic drug to be useful treating cancer cells, which of the following is most desirable?

It interferes with rapidly dividing cells.

Which of the following does not occur during mitosis?

Replication of the DNA

The copying of chromosomes occurs during which of the following phases of the cell cycle? Hint 1. Consider what each phase name stands for.

S phase

At the M phase checkpoint, the complex allows for what to occur?

Separates enzyme cleaves cohesins and allows chromatids to separate.

Movement of the chromosomes during anaphase would be most affected by a drug that prevents

Shortening of microtubules

Which of the following is a function of the S phase in the cell cycle? Hint 1. What does the S in S phase represent?

The synthesis of sister chromatids.

A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 pictograms of DNA per nucleus. How many pictograms would be found at the end of S and the end of G2.

16;16

Is an organism normally has 34 chromosomes, how many molecules of DNA should ther be in the G1 phase of the cell cycle? Hint 1. Review the cell cycle, the timing of DNA replication, and the timing of segregation of chromosomes during mitosis.

34

Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle?

ATP as an energy source.

Density-dependent inhibition is explained by which of the following?

As cells become more numerous, the cell surface proteins of one cell contract the adjoining cells and they stop dividing.

Which of the following is a protein maintained at constant levels through the cell cycle that requires cyclin to become catalytic ally active?

Cdk

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in

Cells with more than one nucleus.

Where do the microtubules of the spindle originate during mitosis in animal cells?

Centresome

Cytochalasin B is a chemical that disrupts micro filaments formation. How would this interfere with cell division? Hint 1. Review the roles of cytoskeleton elements in the M phase of the cell cycle.

Cleavage

The drug Cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by Cytochalasin B.

Cleavage furrow formation and cytokinesis.

True or false? The M phase is characterized by the replication and division of a cells chromosomes.

False.

Which number represents the point in the cell cycle during which the chromosomes are being replicated?

II

MPF reaches its threshold concentration at the end of this stage.

III

The cyclin component of MPF is destroyed toward the end of which phase?

M

Which of the following events would cause the cell cycle to arrest? Hint 1. Consider the assessments that much be made at each of the three checkpoints in the cell cycle.

Poor nutrient conditions.

Which phase are centrioles beginning to move apart in animal cells?

Prophase

For the first several divisions of early frog embryos, cells proceed directly from the M phase to the S phase and back to the M without gaps. Which of the following is likes to be true about dividing cells in early frog embryos?

The cells get smaller with each generation.

Taxol is a cancer drug extracted from the Pacific yew tree. In animal cells, Taxil disrupts microtubules formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin, surprisingly, this stops mitosis. Specifically Taxol must affect

The formation of the mitotic spindle.

During ___ both the contents of the nucleus and the cytoplasm are divided.

The mitotic phase

All cell cycle checkpoints are similar in which way?

They give the go-ahead signal to progress to the next checkpoint.

Which of the following is true concerning cancer cells?

When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.