Virtual Lab: The Cell Cycle and Cancer
1. Open the virtual lab: The Cell Cycle and Cancer
2. Click on the Laboratory Exercise link.
3. Click on the microscope in the lab simulation to examine the different stages of
mitosis as they appear in different tissue samples. Three types of tissue are available
for examination: lung, stomach, and ovary. Samples of normal tissue and cancerous
tissue are included. Click on the tissue box to examine different tissues. Examine both
normal and cancerous tissue for lung and ovary tissue type only. Follow the
instructions to label each stage of the cell cycle.
4. Record the number of cells in each stage of the cell cycle in Table 1 for normal tissues
and Table 2 for cancerous tissues. You must examine three different views of each
tissue type and condition – click reset to view alternate samples of each tissue type until
you have recorded the number of cells in each stage of the cell cycle for 3 different
samples of each tissue.
5. Calculate the average Mitotic Index (% cells dividing) and average % cells at rest for
normal tissues. Record these numbers in Table 3 and 4 on your worksheet.
To calculate the average % cells at rest in normal tissue:
1. (# cells in Interphase in Sample 1 + # cells in Interphase in sample 2) = total #
cells at rest.
2. (total # cells at rest/total #cells in both samples) X 100 = average % cells at rest
To calculate the Mitotic Index - average % cells dividing - in normal tissue:
1. (#cells in mitosis in Sample 1 + #cells in mitosis in Sample 2)/2 = avg. #cells
dividing
2. (avg. # cells dividing/total # cells) X 100 = average % cells dividing
Table 1: Number of cells in each stage of the cell cycle observed in normal tissues.
Tissue
Type
Lung
Tissue
Sample 1
Lung
Tissue
Sample 2
Ovary
Tissue
Sample 1
Ovary
Tissue
Sample 2
# Cells in # Cells in # Cells in # Cells in # Cells in
Interphase Prophase Metaphase Anaphase Telophase
19
1
0
0
0
19
1
0
0
0
18
0
1
1
0
19
1
0
0
0
Table 2: Number of cells in each stage of the cell cycle observed in cancerous tissues.
Tissue
Type
Stomach
Tissue
Sample 1
Stomach
Tissue
Sample 2
Ovary
Tissue
Sample 1
Ovary
Tissue
Sample 2
# Cells in # Cells in # Cells in # Cells in # Cells in
Interphase Prophase Metaphase Anaphase Telophase
14
2
1
1
2
13
2
2
2
1
12
2
1
2
3
10
2
2
3
2
Table 3: Mitotic Index (average % cells dividing) and Avg. % of cells at rest
Tissue Type
Stomach - normal
Ovary - normal
Avg. % cells at
rest
(19/20)+(19/20)/2
X100
= 95%
(18/20)+(19/20)/2
x100
= 92.5%
Mitotic Index
= 100-95
= 5%
= 100-92.5
= 7.5%
Table 4: Mitotic Index (average % cells dividing) and Avg. % of cells at rest
Tissue Type
Avg. % cells at
rest
Stomach - cancerous (14/20)+(13/20)/2
X100
= 67.5%
Ovary - cancerous
(12/20) + (10/20)/2
x 100
= 55 %
Mitotic Index
= 100 – 67.5
= 32.5%
(8/20) + (10/20)/2
x 100
= 45%
Analysis Questions
1.
What does your data indicate about the rate of cell division in
cancerous tissue compared to the rate of cell division in normal
tissue? What data did you use to answer this question?
Cancer cells divide more rapidly and spend more time in
mitosis. I used the mitotic index to come to this conclusion.
2.
With what you have observed in this lab, if you were to compare
tissue sample from normal breast tissue and cancerous breast
tissue:
a. Would you expect to see a difference in the rate of cell division in
the cancerous breast tissue compared to the normal breast tissue?
Explain your answer.
I would expect that cancerous breast tissue has a higher rate of
cell division than normal breast tissue because cancer cells
have a higher mitotic index.
b. Could you make a prediction about the average % dividing cells in
the cancerous breast tissue? Explain your answer.
Difficult to be exact but probably higher than 10% mitotic index
since mitotic index of normal cells seems to be between 5-7.5%.