Classifying the stage of cell cycle in given condition.

1. Identify the position in the cell cycle for all of the following mammalian cells as accurately as possible (that is identify the stage of mitosis if the cell is in M phase.)

a) The cell has no cyclin B present, has mono-phosphorylated cdk1

b) Has no growth factor receptors on its surface

c) Cyclin B is present, the spindle is present, and chromatin is completed condensed

d) Cyclin B is absent, separase is active, and the kinetochore microtubules are shortening

e) The cell can be strongly labeled by adding fluorescent de-oxy-nucleoside triphosphates to its culture medium.

2. I hand you a frozen tube of HeLa cells as well as tell you that they were all in the same stage of the cell cycle when I harvested and froze them.

a) First propose a way to synchronize cells in one stage of the cell cycle.

b) Now define an experiment that will allow you to determine which stage of the cell cycle they were in when I harvested and froze them.