Grade Level/Subject
9 / Biology
Unit
Cell Division
Enduring
Understanding
Organisms grow, reproduce, and maintain
themselves through cell division.
SOL Objectives
BIO.5
Title
Lesson Objective
Inquiry Level
Materials Required
The student will investigate and
understand common mechanisms of
inheritance and protein synthesis. Key
concepts include
a) cell growth and cell division.
BIO.1
The student will demonstrate an
understanding of scientific reasoning,
logic, and the nature of science by
planning and conducting investigations.
Time for the Cell Cycle
Students will be able to recognize which stage
of mitosis a cell is in by viewing its
chromosomes and explain cancer in terms of
the cell cycle.
2 (Question and Methods Given; Solution Open)
Onion root tip slides and / or cards, colored
pencils, protractors, calculators, computers with
internet access.
1
The Time for the Cell Cycle
Problem: How long do cells spend in each phase of the cell cycle?
Objectives:
1. Identify the phases of the cell cycle
2. Determine the amount of time a cell spends in each part of the cell cycle
3. Compare normal cells to cancerous cells; specifically, determine the percentage of
time a normal cell spends actively dividing compared to the percentage of time a
cancerous cell spends actively dividing.
Materials:
1.
2.
3.
4.
5.
6.
Slides or photo cards of onion root tip cells in mitosis
Lab handout
Colored pencils
Protractor
Calculator
Computers with internet access
Part I – The Cell Cycle in the Onion Root Tip
The root tip of an onion (or pretty much
any plant, for that matter) contains a
region of actively dividing cells called the
apical meristem. This is the area in which
cells divide, ultimately leading to what is
called the plant’s primary (up and down)
growth.
Procedure:
1. Each person will receive a slide
or a 3x5 card with a
“photograph” of several onion
root tip cells. If you get the 3 x
5 card, the images here are
similar to what you would see if you were looking at this under a microscope.
2. Count the number of cells that are in each phase of the cell cycle (for the purposes of
this investigation, consider the following phases: interphase, prophase, metaphase,
anaphase, and telophase)
2
3. Record your data in data table I.
4. Combine your counts with the other students at your table so you can share class
data.
5. Record the class data in data table II.
6. Follow the directions below the data table for calculating the percentage of time each
phase takes in the overall cell cycle.
Data Table I
Interphase
Prophase
Metaphase
Anaphase
Telophase
# of cell on
YOUR card
# of cells at
your TABLE
Data Table II
Interphase
Prophase
Metaphase
Anaphase
# of cells – class data
Fraction of cells spent
in this phase (write as
a decimal)
Percent of time in this
phase
Number of degrees in
a circle graph for this
phase
* Look on the next page for directions regarding how to make these calculations.
3
Telophase
Total #
of cells
Directions for calculations (using class data):
1. Add up ALL of the cells in all of the phases and record the total in the total box.
2. Place the number of cells in a particular phase over (to make a fraction) the total number
of cells counted. Divide the top number (the number in a particular phase) by the
bottom number (the total number of cells), and write this in the “Fraction” box.
3. Multiply the decimal number from the previous step by 100 to get the percent of time
and write this in the “percent” box.
4. Multiply the decimal from the “fraction” box by 360 to get the number of degrees in a
circle graph that percent takes up and write it in the “number of degrees” box.
5. Using the circle graph attached to this lab and a protractor, measure out the appropriate
number of degrees for each phase. Shade each section a different color and make sure to
color in the boxes on the key.
6. Don’t forget a title for this graph!
Questions:
1. In which phase of the cell cycle does the cell spend the most time?______________
2. In which phase of the cell cycle does the cell spend the least time?_________________
3. EXPLAIN how / why a slide of stained cells can be used to estimate how much time a
living cell spends in each phase of the cell cycle.
4. You observed the cell cycle in a plant cell in this laboratory. How would the division of
the cytoplasm appear in an animal cell?
4
The circle graph below has been divided into twelve sections, each measuring 30 degrees. You
can use these lines as a reference when measuring out the specific degrees that you need to
accurately represent each phase of the cell cycle below. Remember to give this graph a title and
include a key showing which color represents which phase of the cell cycle.
Title: _______________________________________________________________________________
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Part II – Cancer and the Cell Cycle
Normally, the cell cycle has a system of
checks and balances to make sure that cells
are dividing at the appropriate rate.
Sometimes, for a number of reasons, those
checks and balances fail. When this
happens, and a cell begins to divide
uncontrollably, that cell has become
cancerous.
The figure at the right illustrates some of the
most common differences between normal
cells and cancerous cells. In the next portion
of this investigation, you will utilize an
online simulation to view differences in the
rate of cell division between normal cells
and those that have become cancerous.
Procedure:
1. Go to:
http://www.glencoe.com/sites/common_assets/advanced_placement/mader10e/virtual_la
bs_2K8/labs/BL_03/
2. Click on the Monitor to watch a short video on the cell cycle.
3. Click on the Information button in the lower right to get some background on cancer.
4. Click on the Microscope and examine all six slides (Lung – normal and cancerous,
Stomach – normal and cancerous, Ovary – normal and cancerous).
5. For each slide, label the indicated cells using the drag and drop labels. Then check your
work and record the data for _every_ cell on the slide (not just the few that you labeled)
in the data table by clicking the Data Table button in the virtual lab.
6. For each slide, calculate the percentage of cells that are dividing and the percentage that
are at rest (this should add up to 100%). Record this in the data table as well.
7. After you have examined all six slides, click on the Journal button and answer the three
questions there.
8.
Follow your teacher’s directions as to whether you should submit your work
electronically (by clicking the Submit button in both the Data Table and the Journal and
entering your email address and your teacher’s email address; note: you have to submit
each of these items separately) or print out a hard copy to attach to this lab and turn in.
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