One potential medical treatment to stop cancer cell proliferation employs an inhibitor derived from human umbilical cord stem cells. In this question, you will compare two histograms to determine where in the cell cycle the inhibitor blocks the division of cancer cells.
In the treated sample, human glioblastoma (brain cancer cells) were grown in tissue culture in the presence of the inhibitor. In contrast, control sample glioblastoma cells were grown in the absence of stem cells. To get a ?snapshot? of the phase of the cell cycle each cell was in at the end of 72 hours, the cell samples were treated with a fluorescent chemical that binds to DNA. Next the samples were run through a flow cytometer, an instrument that records the fluorescence level of each cell. Computer software then graphed the number of cells in each sample with a particular fluorescence level.
The data are plotted in a type of graph called a histogram, which groups values for a numeric variable on the x-axis into intervals. A histogram allows you to see how an entire group of experimental subjects (cells, in this case) are distributed along a continuous variable (amount of fluorescence). In these histograms, the bars are so narrow that the data appear to follow a curve for which you can detect peaks and dips. Each bar represents the number of cells observed to have a fluorescence level in that interval. This in turn indicates the relative amount of DNA in those cells.
Analyze the graph carefully and focus on what each axis means. The y axis is giving you number of cells, and the x axis is giving you amount of fluorescence per cell. remember that these cells were stained with a fluorescent dye that binds DNA. After analyzing the graph, answer the following questions:
One potential medical treatment to stop cancer cel
Identify which phase of the cell cycle is represented by each region. The regions represent the same cell cycle phases in both histograms.
A) region A: G1
region B: S
region C: G2
B) region A: S
region B: G1
region C: G2
C) region A: G1
region B: G2
region C: S
D) region A: G2
region B: S
region C: G1