Getting  Started
Several compounds were tested in your lab as putative cell cycle inhibitors. Your job is to study the effects of substance X on cell cycle progression and to analyze its mode of action.

In your initial screening test you exposed a non synchronized culture of exponentially growing mouse fibroblasts to substance X for 24 hrs.

  1. Isn't that exposure too long?

You then evaluated the number of cells in each phase of the cell cycle by DNA staining with propidium iodide followed by FACS analysis.
 

Examine the results:
TREATMENT
G1
S
G2/M
Non-treated cells
55
16
29
Substance X treatment
95
2
3
  
2. How does substance X affect the cells?
(Choose between wrong and possible)
A. It does not alter the cell cycle.
B. It arrests cells before the restriction point.
C. It arrests cells before the G1/S transition point.
D. It arrests cells during S phase.
E. It arests cells before the G2/M transition point.
F. It arrests cells during M phase.
G. It accelerates the transition of the cells through G0 and induces arrest in G1.
 
 
 





































































3. Is it possible that substance X arrests cells in additional points
that are not observed in this experiment?
 
First, think

Than click here for an answer).

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

.