11. Cell Division

Cells spend the majority of their time in which one of the following phases of the cell cycle?

The first phase in the cell cycle (G1) corresponds to ___________.

Which pair includes a phase of the cell cycle and a cellular process that occurs during that phase?

What is the name of the microtubule-organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle?

a) Spindle.

b) Centromere.

c) Centrosome.

d) Kinetochore.

What is the role of the spindle fibers during mitosis?

It is difficult to observe individual chromosomes during interphase because a. the DNA has not been replicated yet. b. they are in the form of long, thin strands. c. they leave the nucleus and are dispersed to other parts of the cell. d. homologous chromosomes do not pair up until division starts.

A particular cell type spends 4 hours in G1 phase, 2 hours in S phase, 2 hours in G2 phase, and 30 minutes in M phase. If a pulse–chase experiment were performed with radioactive thymidine on an asynchronous culture of such cells, what percentage of mitotic cells would be radiolabeled 9 hours after the pulse? a. 0 percent b. 50 percent c. 75 percent d. 100 percent