Cell Cycle Lab
 Examining Mitosis in the root tip of Allium
 Already prepared on microscope slides
 Objective to observe and identify Interphase,
Prophase, Metaphase, Anaphase, and Telophase
Mitosis Phases
Interphase. The cell is engaged in metabolic activity and performing its
duty as part of a tissue. The DNA duplicates during interphase to prepare
for mitosis (the next four phases that lead up to and include nuclear
division). Chromosomes are not clearly discerned in the nucleus,
although a dark spot called the nucleolus may be visible.
Prophase. Chromatin in the nucleus begins to condense and becomes
visible in the light microscope as chromosomes. The nuclear membrane
dissolves, marking the beginning of prometaphase. Proteins attach to the
centromeres creating the kinetochores. Microtubules attach at the
kinetochores and the chromosomes begin moving.
Metaphase. Spindle fibers align the chromosomes along the middle of
the cell nucleus. This line is referred to as the metaphase plate. This
organization helps to ensure that in the next phase, when the
chromosomes are separated, each new nucleus will receive one copy of
each chromosome.
Anaphase. The paired chromosomes separate at the kinetochores and
move to opposite sides of the cell. Motion results from a combination of
kinetochore movement along the spindle microtubules and through the
physical interaction of polar microtubules.
Telophase. New membranes form around the daughter nuclei while the
chromosomes disperse and are no longer visible under the light
microscope. Cytokinesis or the partitioning of the cell may also begin
during this stage.
Lab
 Groups of 2
 1 microscope per group
 1 microscope slide per group
 View slide at 40X
 Count 100 cells
 One group member will observe and one will mark done
observations for 50 cells. Then switch and observe remaining
50 cells on a different part of the slide.
1 interphase
2 interphase
3 early prophase
4 mid prophase
5 late prophase
6 metaphase
7 early anaphase
8 anaphase
9 early telophase
10 telophase
Microscope Usage
 Handle microscope with 2 hands
 One hand on the base and one hand holding arm of scope
 Focus at 4X first
 Only time you use course focus (large knob)
 Then focus at 10X using fine focus (small knob)
 Switch to 40X and focus using fine focus
Lab
 Make table of your small group’s
observations:
Interphase
Prophase
Metaphase
Anaphase
Telophase
20
20
20
20
20
 Pool class data into table

Fill in excel document in class
Meta
Telo
Observer Interp Prop phas Anap phas To
(Group) hase hase e
hase e
tal
Group 1
0
Group 2
0
Group 3
0
Group 4
0
Group 5
0
Group 6
0
TOTAL
0
0
0
0
0 0
Lab Report
 Introduction:
 Background about cell cycle


What are the stages and what is happening in each stage
Hypothesis

Relative amount of time spent in each stage
Lab Report
 Methods:
 Prepared slides
 Count cells/ determine stage
 Discuss calculations
Lab Report
 Results:
 Include
table of class data for each phase
 Calculate mean, S.D., and S.E. of CLASS
DATA for each phase
 Generate table of small group results
Interphase
Prophase
Metaphase
Anaphase
Telophase
20
20
20
20
20
Lab Report
 Calculate amount of time cells spent in each stage
of mitosis.
 Example:
 Calculate percentage of time spent in a specific stage from class
data


Interphase: 756/1200 X 100 = 63%
Use percentage to calculate time spent in stage




16 hours (time it takes to complete cell cycle) x 0.63 = 10.08 hours
0.08 hours x 60 minutes/1 hour = 4.8 minutes
0.8 minutes x 60 seconds/1 minute = 48 seconds
Answer = 10 hours 4 mins 48 seconds in interphase
Lab Report
 Calculate variability measurement Used to measure
variability of class in determination of stages

Higher number indicates more variability
Use class data to calculate variability
 Calculate for each stage
 Variability = S.E./Mean

Lab Report
 Results
 Make pie chart of the percentage of time spent in each
stage
 Use class data for chart
Telophase, 6%
Anaphase, 9%
Metaphase, 7%
Prophase, 15%
Interphase, 63%
Lab Report
 Discussion
 Meaning of lab
Why might certain phases take longer, etc.
 Importance of cell cycle

Lab Report
 Conclusion
 Hypothesis supported? Why/ why not
Lab Report
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Introduction
___ Describe cell cycle
___ Discuss cell cycle
Methods
___ Counting
___ What the numbers tell us
Results
___ Class Data and Calculations (1.5 pts)
___ Individual Data (0.5 pt)
___ Pie Chart
___ Conversion from percent to time
Discussion
___ Discuss meaning of the lab
Conclusion
___ Hypotheses