This lab was reworked from a lab entitled ‘Time For Mitosis’ that came from a very old
lab book from Merrill.
I’ve found that it works very well in reinforcing the phases of mitosis once they’ve
identified each phase on a slide and drives the students crazy. I’ve included a blank
version and provided the question answers (below).
1. interphase
2. growth, replication of DNA, etc.
3. prophase
4. anaphase
5. interphase
6. prophase
7. they are the same
8. yes- changes occurring during mitosis require specific time for completion.
9. the time for each phase in cancer cells is much shorter than in normal cells
10. total time is much shorter in cancer cells
11. too little time is spent in each phase and in completion of the entire process.
Abnormal cells result from this abnormal sequence.
12. pea
13. they are both plants
Note on the circle graph( if their data is correct the largest area should be interphase
followed by prophase, metaphase, telophase and anaphase in that order.
Time for Mitosis
Introduction: In order to determine whether all phases of mitosis take the same amount of
time, a counting exercise can be done using longitudinal sections of an Allium (onion)
root tip. By counting the number of cells that are the four stages of mitosis and
interphase, it can be determined how much time is spent in any one phase with surprising
accuracy.
In this investigation, you will use prepared slides of Allium root tip cells to locate cells
that are in various stages of mitosis and interphase. You will count the number of cells in
each of the mitosis phases and interphase in three different areas and compute the length
of time needed to complete each phase. In the analysis, you will compare the time needed
for normal cells of one species to complete each phase with that of cancerous cells from
the same species as well as times from the normal cells of two different species.
Materials:
Microscope
Longitudinal section of Allium root tip slides
Part 1
1. Locate under a microscope a region of rapidly dividing cells on an Allium slide.
After locating the region under low power, switch to high power.
2. Making sure you have a full field of view, count and tally the phase of mitosis or
interphase that each cell is in. Count all cells in your field of view. Record your
tallies in table 1.
3. Switch to another area or root tip if the slide has more than one. Repeat procedure
for a second area.
4. Repeat for a third new area, recording all tallies in table 1.
5. Total the number of cells for the three areas and fill out the fourth column in table
1.
Part 2
1. Let us assume that an onion root cell requires about 12 hours (720 minutes) to
complete one cycle (from interphase to interphase).
2. Therefore the time spent in each phase can be determined using the following
formula:
number of cells in a phase/ total number of cells counted X 720 minutes =
the time in minutes for each phase.
For example: if you counted a total of 326 cells and 46 of them were in prophase,
then the time spent in prophase would be:
46/326 x 720 = 101 minutes
3. Calculate the time in minutes and record it in the last column of table 1.
Part 3
Using the data from table 1, construct a circle graph using the template below which
shows the number of minutes that onion cells spend in each phase of mitosis.
Suggestions for the graph:
-use the time in minutes portion of your table
- each segment of the graph represents 18 minutes, so if your data is not in exactly
18minute increments, approximate the position of the line on the graph.
- use colored pencils to shade in each area
- make a legend/key that tells what each colored section represents.
Data Tables:
Table 1
Phase
first area
second area
third area
Interphase
Prophase
Metaphase
Anaphase
Telophase
total # cells
counted
total # of cells
time in minutes
Circle graph
Lab Analysis:
1. Which phase requires the longest time for completion?
___________________________________________
2. What important changes are occurring to the nucleus and cell during the longest
phase? ____________________________________________________________
__________________________________________________________________
__________________________________________________________________
3. Which phase requires the next longest amount of time? ______________________
4. Which phase requires the shortest time for completion? ______________________
Table 2 – time for mitosis of normal and cancerous chicken stomach cells
normal chicken stomach cells in
minutes
cancerous chicken stomach cells in
minutes
interphase
540
75
prophase
60
15
metaphase
10
2
anaphase
3
1
telophase
12
3
5. Which phase for normal cells requires the longest time for completion?
______________________________________________________
6. Which phase for normal cells requires the next longest time for completion?
_______________________________________________________
7. How do these answers compare with your onion data? ________________________
______________________________________________________________________
______________________________________________________________________
8. In general, might all cells have a similar pattern? ____________ Why? __________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
9. How do cancer cells differ from normal cells in time spent for each phase? ________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
10. How do cancer cells differ from normal cells in total time required for mitosis?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
11. Cancer is abnormal mitosis. In what regards might it be abnormal?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Table 3 shows the length of time in minutes needed for mitosis to occur in two different
normal living organisms.
Table 3 Times needed for mitosis
prophase
metaphase
anaphase
telophase
total
salamander kidney
cells
60
50
6
70
186
pea root cells
80
40
4
12
136
12. Which organism, the salamander or the pea, shows time needed to complete mitosis
most like the data that you recorded in table 1?
______________________________________________________________________
13. Why do you think this is? ______________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________