ch 12 quiz

Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following?

two long strands of DNA plus proteins

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

centrosome

The centromere is a region in which

chromatids remain attached to one another until anaphase

One difference between cancer cells and normal cells is that cancer cells

continue to divide even when they are tightly packed together

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?

lack of appropriate cell death

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

prevents shortening of microtubules

At which phase are centrioles beginning to move apart in animal cells?

prophase

Which of the following does not occur during mitosis?

replication of the DNA

If there are 20 chromatids in a cell, how many centromeres are there?

10

For anaphase to begin, which of the following must occur?

Cohesin must be cleaved enzymatically

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in

G1

Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?

Golgi-derived vesicles

Which of the following most accurately describes a cyclin?

It activates a Cdk molecule when it is in sufficient concentration

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

M

Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?

MPF

A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation?

The cell would undergo normal mitosis, but fail to enter the next G1 phase

Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis?

The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules.

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely

a plant cell in the process of cytokinesis

The MPF protein complex turns itself off by

activating a process that destroys cyclin components

Why do chromosomes coil during mitosis?

to allow the chromosomes to move without becoming entangled and breaking