Hoechst 33342 is a membrane-permeant dye that fluoresces when it binds to DNA. When a population of cells is incubated briefly with Hoechst dye and then sorted in a flow cytometer, which measures the fluorescence of each cell, the cells display various levels of fluorescence as shown in Figure Q17–1.

A. Which cells in Figure Q17–1 are in the G1, S, G2, and M phases of the cell cycle? Explain the basis for your answer.

B. Sketch the sorting distributions you would expect for cells that were treated with inhibitors that block the cell cycle in the G1, S, or M phase. Explain your reasoning.

Figure Q17-1

Transcribed Image Text:

1 relative fluorescence per cell 2 number of cells