Problem
You can estimate how much time a cell spends in different stages of the cell cycle by calculating the percentage of cells in the different stages at one time. Assume that upon examination of a sample of 1000 cells, you find 50 cells in prophase, 20 in metaphase, 10 in anaphase, 20 in telophase and 900 in interphase. Of those in interphase, 400 are found (by analysis after staining the cells with a DNA - specific stain) to have X amount of DNA, 200 to have 2X amount, and 300 cells to be somewhere in between. Further analysis indicates that the G2 phase lasted 4 hours.
Task
A. Calculate the proportion of the cell cycle spent in each of the following phases: prophase, metaphase, anaphase, telophase, and interphase. (HINT: the proportion of time spent in each stage is the same as the percentage of cells in each stage.)
B. Calculate the proportion of the cell cycle spent in G1, S, and G2.
C. What is the total length of time (in hours) of the cell cycle?
D. What is the actual amount of time (in hours) spent in each of the phases of the cell cycle?