Laboratory: Timing of the Cell Cycle
Name ________________________
Introduction:
How long do onion root tip cells spend in each phase of the cell cycle? In this
computer lab you will identify the phases of the cell cycle. You will also determine the
time an onion cell spends in each part of the cell cycle.
Webpage: http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/01.html
Procedure:
1.
2.
3.
4.
5.
6.
Open the webpage
Examine the picture of the cell in mitosis and identify the phase that it belongs in by
clicking on the name of the phase.
Continue to do this until you have identified 36 cells and record the number of cells
in Row A
Calculate the fraction of cells in each phase by dividing the number of cells in that
phase by the total number of cells you counted (36). Record your fraction in Row
B. Express your answer as a decimal in Row C. You may need to round to the
nearest hundredth. For example, .576 rounds to .58
Calculate the number of degrees in a circle graph for each phase by multiplying
the time, expressed as a decimal (Row C) by 360° (the number of degrees in a
circle.) Record your degree value in Row D. You may need to round to the nearest
degree. For example, 87.56 degrees will round to 88 degrees.
Make a circle graph showing the amount of time, in degrees, a cell spends in each
phase of the cell cycle. Color each portion of the circle a different color. Label
each portion with the phase, percent value, and the degrees. Make a key/legend
that indicates which phase each color represents.
Data Table:
Interphase Prophase Metaphase Anaphase
Telophase
Row A
Total # of cells in
each phase
Row B
Fraction of cells in
this phase
= 36
36
Row C
Time cell spends in
this phase
expressed as a
decimal
Row D
Number of degrees
in a circle graph for
this phase
36
36
36
36
= 36/36
= 1.0
= 360o
Title of Graph _______________________________
Key:
Interphase
Prophase
Metaphase
Anaphase
Telophase
Discussion:
1. In which phase of the cell cycle does a cell spend most of its time? _______________________
In which phase of the cell cycle does a cell spend the least time? _______________________
2.
Compare your pie graph to the cell cycle graph from your notes.
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