Mitosis Lab
Name: _______________________________________ Date: ______________ Class___________ Seat: _________
One of the basic tenets of biology is that all new cells come from living cells. New cells are formed by the process of cell division which includes both the division of the cell’s nucleus (mitosis) and the division of the cells cytoplasm
(cytokinesis). Mitotic nuclear division typically rests in new somatic (body) cells. All of the following processes are accomplished through mitotic cell division:
● Formation of an adult organism from a fertilized egg (zygote)
● Asexual reproduction (as in the reproduction of an Amoeba or Paramecium)
● Regeneration (as in the re-growth of a starfish arm)
● Repair or maintenance of body parts (as in the healing of a wound or the replacement of epithelial tissue)
● Growth (as in the growth in height of a tree or growth in size of a maturing animal)
Although, once it has started, mitosis is a continuous process, scientists have divided it into distinct stages for convenience and ease of study and understanding of the cellular events. These are illustrated below in Figure 1 (for plant cells).
Figure 1
In this lab we will be viewing sections of tissue containing mitotic cells and determining what stages each of the cells is in and estimating how long each stage lasts. We will also be comparing normal cells and cancer cells to see how mitosis is altered in cancer cells.
Where does one find cells undergoing mitosis? It depends if you are studying plants or animals. Plants and animals differ in this respect. In higher plants (gymnosperms and angiosperms), the process of forming new cells is restricted to special growth regions called meristems. These regions usually occur at the tips of the stems and roots of the plant. In animals, cell division occurs in many tissues and in many organs throughout the body—whenever cells receive the appropriate signals to form new cells, possibly for growth or to repair an injury or to replace old cells.
However, some tissues in both plants and animals rarely divide once the organism is mature, like nerve cells or muscle cells in animals or mature xylem or phloem in plants.
PART 1. NORMAL MITOSIS IN PLANTS
1.
Go to this website: http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html
2.
Follow the directions in the activity and fill out the table below.
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Mitosis Lab
Table 1 Count of cells in various parts of the cell cycle
Prophase Metaphase
# of cells
% of cells
Interphase Anaphase Telophase Total
36
3.
Calculating the time for each stage of mitosis. There is a direct relationship between the number of cells counted in a given stage of mitosis and the time that that stage takes to complete. This may be calculated if the total time for mitosis in onion root tip cells is known. This is usually measured from interphase to interphase. It is generally accepted that the totally time for mitosis in onion root tips cells is 720 minutes (12 hours). How would you calculate the time for each stage of mitosis in these onion cells?
4.
Calculate the time spent in each stage of mitosis. Show all of your work! Complete the table below.
Table 2. Time spent in each stage of mitosis in onion cells.
Time spent in each phase
% of Time spent in each phase
Interphase Prophase Metaphase Anaphase Telophase Total
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Mitosis Lab
5.
Graph the data below.
6.
Why are onion root tips used to find and analyze cells in mitosis?
7.
List the stages of the cell cycle and mitosis from longest to shortest duration.
8.
Explain your results (CER)!!
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Mitosis Lab
The effects of Environment on Mitosis
Scientists reported that a fungal pathogen may negatively affect the growth of soybeans (Glycine max). Soybean growth decreased during three years of high rainfall and the soybean roots were poorly developed. A lectin like protein was found in the soil around the soybean roots. This protein may have been secreted by the fungus. Lectins induce mitosis in some root apical meristem tissues. In many instances, rapid cell divisions weaken plant tissues.
You have been asked to investigate whether the fungal pathogen that produces lectin affects the number of cells undergoing mitosis in root tips of plants.
1.
How would you design an experiment to test whether lectins increase the number of cells in mitosis? Be sure to include all parts of a controlled experiment in your design!
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Mitosis Lab
Hypothetical data for an experiment testing lectins effect on mitosis is listed below. Each group counted cells found in interphase and cells found in mitosis in three different root tips for both a control group and an experimental group.
2.
Calculate the % of time spent in mitosis and interphase and mean for each group. SHOW YOUR WORK!!!!
Table 1.
Onion Root Tip Cell Phase Data; Control Group (Onion root tips grown under normal conditions)
Number of Cells Interphase Mitotic
Tip
1
Interphase
134
Mitotic
16
Total
150
Mean
%
2
3
201
128
29
14
230
142
Total
Table 2.
Onion Root Tip Cell Phase Data; Experimental Group (Onion root tips grown in presence of lectin)
Number of Cells Interphase Mitotic
Tip
1
2
3
Total
Interphase Mitotic
194 9
170
263
6
13
Total
203
176
266
Mean
%
Table 1.
Onion Root Tip Cell Phase Data; Control Group (Onion root tips grown under normal conditions)
Tip
1
2
3
Total
Number of Cells
Interphase Mitotic
227
166
28
18
239 25
Total
255
184
264
Mean
%
Interphase Mitotic
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Mitosis Lab
Table 2.
Onion Root Tip Cell Phase Data; Experimental Group (Onion root tips grown in presence of lectin)
Tip
1
2
3
Total
Number of Cells
Interphase Mitotic
192
184
9
11
205 9
Total
201
195
214
Mean
%
Interphase Mitotic
Table 1.
Onion Root Tip Cell Phase Data; Control Group (Onion root tips grown under normal conditions)
Tip
1
2
3
Total
1
2
3
Total
Interphase
200
130
177
157
189
195
Number of Cells
Mitotic
22
16
21
11
9
9
Total
222
146
198
Total
165
198
204
Mean
%
%
Interphase Mitotic
Table 2.
Onion Root Tip Cell Phase Data; Experimental Group (Onion root tips grown in presence of lectin)
Tip
Number of Cells
Interphase Mitotic Mean
Interphase Mitotic
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Mitosis Lab
(compile all data from three groups given above).
Interphase Cells
Mitotic Cells
Total
Control Group Experimental Group
3.
Compare the number of cells from each group in interphase and in mitosis.
Analysis Questions
1.
What was the importance of collecting the class data?
2.
Was there a significant difference between the groups? Explain (CER!!)
3.
Did the fungal pathogen that produces lectin increase the number of root tip cells in mitosis? Explain.
4.
What other experiments should you perform to verify your findings?
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Mitosis Lab
5.
Does an increased number of cells in mitosis mean that these cells are dividing faster than the cells in the roots with a lower number of cells in mitosis? Explain.
6.
What other way could you determine how fast the rate of mitosis is occurring in root tips?
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Mitosis Lab
PART 2. SIMULATING MITOSIS
1.
Using the pop beads, model the cell cycle. Begin with a cell that has 4 chromosomes (2 pair of homologous chromosomes; 2N=4)
2.
Be able to explain each step.
3.
Diagram each step in the table below. Use red and yellow to represent each of the homologs.
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Mitosis Lab
PART 3. MITOTIC DIVISION IN CANCER CELLS
A key characteristic of cancer cells is that they are no longer constrained by the standard cell cycle controls that normally coordinate cell division activity. Consequently the timing of the cell cycle in cancer cells is altered. You may have heard of cancer cells being called “runaway” cells which have no controls on their rate of reproduction. It is this characteristic that allows some cancer cells to growth and spread quite rapidly. In this section of the lab, you will analyze data to determine the differences in timing of mitosis between normal stomach cells and cancerous stomach cells of the chicken.
Data Table 1.
Cell Cycle in Normal Chicken Stomach Cells
Stage of
Mitosis
Total #
Cells
Time in
Minutes
% of Cell
Cycle
Data Table 2.
Cell Cycle in Cancerous Chicken Stomach Cells
Stage of
Mitosis
Total #
Cells
Time in
Minutes
% of Cell
Cycle
Interphase 440
Prophase 40
Metaphase 8
Anaphase 2
Telophase 10
Totals 500 625 100%
Interphase
Prophase
Metaphase
Anaphase
Telophase
424
50
12
3
11
Totals 500 448 100%
1.
Study the data in table 2 above. Assume that the total time needed for one normal mitotic division of these cells is 625 minutes. Calculate the total time needed for each normal phase of mitosis. Calculate the percentage of the cell cycle spent in each phase. Enter these data in Table 1.
2.
Repeat the same analysis for the data in Table 2.
3.
Graph your results.
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Mitosis Lab
Summary Questions
1.
Compare the data for each phase in the normal chicken cell to that of the onion root cell.
2.
What conclusion(s) can you draw based on your comparison?
3.
Compare the timing of the complete cell cycle in normal chicken cells to that of cancerous chicken cells.
4.
Which stage exhibits the most dramatic difference in timing between normal and canerous chicken cells?
_________________ Explain your answer.
5.
What nuclear and cytoplasmic changes would you expect to find in cancer cells, as compared to their normal counterparts? (i.e. what events would be most affected by the alteration in timing sequence of mitosis?
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Mitosis Lab
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