9. Think back to the pre-lab questions about the differences in plant and animal cell mitosis. Were your predictions correct? What, if any, differences did you actually see?
“If the division of plant and animal cells is observed, the plant cells will not change shape during division while the animal cells will form cleavage, morph and form two rounded cells.” Because this was my prediction, it was correct. The animal cells change and morph and as the plant cells divide, they do not change shape.
Exercise 2: Calculate the Percentage of Time Spent in Each Stage of Mitosis
Data Collections:
Number of Cells in each phase of mitosis:
Interphase
Prophase
Metaphase
Anaphase
Telophase (Cytokinesis)
Total
Number of Cells #1
2
1
11
2
2
21
Number of Cells #2
1
3
4
3
2
15
Number of Cells #3
3
4
6
2
3
21
Total
6
8
21
7
7
57
11%
14%
37%
12%
12%
100%
Based on this table, metaphase is the most prominent phase in whitefish blastula. This may be an observation error, or an error based on a low number of images to observe and compare. Based on my research, interphase should be longest by a large margin, followed by metaphase. Prophase, anaphase and telophase should all be relatively equal.
Analysis:
1. Calculate the percentage of time the cells spent in each stage of the cell cycle for each field of view independently.
Calculated based on a 60min cycle:
Interphase
Prophase
Metaphase
Anaphase
Telophase (Cytokinesis)
Total in Mitosis
Number of Cells #1
5.7min
2.8min
31.4min
5.7min
5.7min
51.3min
Number of Cells #2
4min
12min
16min
12min
8min
52min
Number of Cells #3
8.6min
11.4min
17.1min
5.7min
8.6min
51.4min
2. Now sum the numbers from all four data sets and use the totals to calculate the percentage of time the cells spent in each stage of the cell cycle.
All Cells
Time spent in Each Phase
Interphase
6.6min
Prophase
8.4min
Metaphase
22.2min
Anaphase
7.2min
Telophase
7.2min
Total time for all Cells
51min
3. Compare the time the cells spent in each stage of the cell cycle from the summed data to that from the individual data do you notice any differences?
There are slight variations in the amount of cells in each stage of mitosis in each view of cells. When compared to the other stages of mitosis rather than the three different views, the data supports a common factor, where metaphase is the longest stage and all other stages and similar in time spent. This may be an observation error, because interphase should account for approximately 90% of the cells life.
4. In the above example of a standard deviation calculation your calculator would have displayed the result as 1.11803398… Why did we only display 1.1 as the answer?
A final product of data will be rounded up from its calculated result, and rounding to one decimal place ensures and accurate representation.
5. Calculate the standard deviation for each of your cell stages. List the length of time each cell spends in each stage of the cell cycle with its standard deviation below, in this format: time in stage +/- standard deviation.
All Cells
1. Calculate the mitotic index for each region. Modify your table from question one and enter the mitotic index in your new table.
Onion Root Cells in Each Region and their Mitotic Index:
2. Calculate the size of the cells for each region and record that in your table from question 11. The total field of view for you microscope is 305µm at 40X and 205µm at 60X.
Cap Cells
Meristem
Elongation
Maturation
Size
1.2um
1um
2.8um
5.1um
Mitotic Index
30
51.3
12
10
3. How does your prediction of the relationship of the mitotic index to cell size correlate with the data you collected? “If interphase is being observed, then the cell will be at its largest size
