Treatment of Dividing Cells with a Low Dose of the Antifungal

Multiple Choice

Treatment of dividing cells with a low dose of the antifungal drug benomyl, which destabilizes microtubules, slows down correct spindle assembly. But at such doses, the spindle is eventually formed and the cells survive. However, mutations in some genes confer benomyl sensitivity: the mutant cells die because they fail to arrest the cell cycle in the presence of unattached kinetochores and progress through anaphase, with disastrous consequences. Which of the following would you expect to be a benomyl-sensitive mutant?

A) A loss-of-function mutant in the gene encoding Mad2.
B) A mutation causing the overexpression of Cdc20.
C) A loss-of-function mutation in the gene encoding a kinase that inhibits Cdc20-APC/C.
D) A loss-of-function mutation in the gene encoding a tubulin subunit.
E) All of the above.