After S phase, what makes up a single chromosome?

a. Two daughter chromosomes

b. A double-stranded DNA molecule

c. Two single-stranded DNA molecules

d. Two sister chromatids

Progression through the cell cycle is regulated by oscillations in the concentration of which type of molecule?

a. p53, Rb, and other tumor suppressors

b. Receptor tyrosine kinases

c. Cyclins

d. Cyclin-dependent kinases

What major events occur during anaphase of mitosis?

Identify at least two events in the cell cycle that must be completed successfully for daughter cells to share an identical complement of chromosomes.

What evidence suggests that during anaphase, kinetochore microtubules shorten at the kinetochore?

Compare and contrast the effects of removing growth factors from asynchronous cultures of human cells that are normal and those that are cancerous.

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

When a fruit fly embryo first begins to develop, a large cell is generated that contains over 8000 genetically identical nuclei. What is most likely responsible for this result?