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Mitosis Lab – Lab 3
Objectives:
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To describe the events of the cell cycle and how these events are controlled.
To explain how DNA is transmitted to the next generation via mitosis.
To examine the statistical validity of data using Chi-Square.
I.
Purpose:
Write a purpose questions based on the above objectives.
Background: Read through the background. Identify the following key terms and highlight them. Include
them in your background lab summary: cell division, cell cycle, interphase, G1, S, G2, mitosis, cytokinesis,
cyclin-dependent kinase, cyclin, mitosis-promoting factor, and cancer cell.
Hypothesis – write one that answers your purpose question.
II. Materials:
Mitosis Cards
Calculator
III. Procedure:
1. Count the number of cells in each of the following stages of the cell cycle. Record in your data table
2. Repeat for 3 different mitosis cards.
3. Calculate the total number on all 3 cards.
4. Calculate the percent of time onion cells spend in each stage of the cell cycle.
5. Calculate the amount of time (in 24 hours) a cell spends in each stage of the cell cycle.
6. Perform a Chi Square Analysis to support or reject the null hypothesis that the treatment of the cells
with lectin has no effect on the percentage of time cells spend in mitosis.
IV. Data:
Copy the following data tables prior to coming to lab.
Table 1 – Group Data
Stages
Number of Cells
Card 2
Card 3
Card 1
Total
% of Total
Cells Counted
Interphase
Prophase
Metaphase
Anaphase
Telophase
Table 2 – Class Average Data
Interphase
Mitosis
Total
Table 3 – Lectin Treated Data Comparison Table
Interphase
Control (Class Data)
Lectin Treated
Total
161
Mitosis
88
Total
249
Time in Each
Stage
V. Results:
1. Create a graph depicting the relative amount of time spent in each phase of the cell cycle.
2. Use the following information to perform a Chi-Square Analysis to compare your data with the data
below which shows the results of cells treated with lectin a mitosis inducing protein.
Table 1 – Table of Observed Values (o)
Table 2 – Table of Expected Values (e)
Table 3 – Calculation of Chi-Square Value
Group
Control
Interphase
Control Mitosis
Observed (o)
Expected (e)
(o-e)
(o-e)2
Treated
Interphase
Treated Mitosis
Total of (o-e)2/e = Chi Square (x2) =
Table 4 – Critical Values of the Chi Square Distribution
(o-e)2/e
VI. Questions:
1. Explain how mitosis leads to 2 daughter cells that are diploid and genetically identical to the parent cell.
2. What activities occur during interphase?
3. How does mitosis differ in plant and animal cells?
4. What is the role of the centrosome in mitosis?
5. What additional structure do animal cells have to aid them in mitosis?
6. Why is a root tip a good location to study mitosis?
7. How might looking at a fully developed stem change the percentages of cells in mitosis versus
interphase?
8. What percentage of time does a root cell spend in the following phases: interphase, prophase,
metaphase, anaphase, and telophase.
9. How is cell division different in prokaryotes compared with eukaryotes?
10. How is the cell cycle controlled to ensure proper regulation of cell division?
11. What goes wrong in the cell cycle in cancer cells?
12. How did the protein lectin affect the rate of mitosis in the root cells?
VII. Conclusion
Follow our Claim, Evidence and Reasoning format.