Cell Cycle and Dividing Cells Number

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Science 9-Biology

Observing Cell Division Lab

Purpose:
To use the microscope to observe and sketch plant cells and animal cells in various stages of the cell cycle.

Equipment and Materials:

Compound Microscope
Laptops
Prepared Slide of Onion (Allium) Root Tips
Prepared Slide of Whitefish Mitosis
BC Science 9 Text pg. 162-163

Part 1-Plant Cells

Procedure:

1.Take a prepared slide of an onion tip root and observe it under low power (40X). Move the slide around until you have a section near the tip that is in clear focus. Now, increase the power of magnification (400X). Select an area and count out about 100 cells (approximately). Notice if the cells are:

a) Dividing (chromosomes visible, no nucleus),
b) Not dividing (nucleus visible, no chromosomes)

Fill in the following table:
|Out of about 100 cells: | |Number of Dividing Cells |Number of Cells Not Dividing | | | | | | |

At any one time are most cells dividing or not-dividing? ___________________________

Look at the diagram of a plant cell

undergoing cytokinesis. Notice the
thin layer of membrane in the center.
This is called the Cell Plate.

Can you see any cells that appear as if
they are undergoing cytokinesis?

________________________________

2.The following diagram shows onion root tip cells in the various stages of mitosis. Study these pictures.

If you need to look at more images of mitosis in onion root tips, log on to a computer and go to the web sites: http://micro.magnet.fsu.edu/micro/gallery/mitosis/mitosis.html or
http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html or
http://staff.jccc.net/pdecell/celldivision/oniontip.html

You can link to these more easily by going to Mr. Roberts’ Science 9 Web page, scrolling down to “Biology” and finding “Web Links” > “Observing Cell Division”.

3.Now go back to your microscope and focus on a portion near the tip of the root. Focus in medium power, then in high power (400 X).

Try to find individual cells in each stage of mitosis and a cell undergoing cytokinesis (cell plate forming). Use the web links to see better images of each stage of the cell cycle.

Using pencil, make a neat sketch of each one of these cells on the next page; label key parts in each diagram.

The Stages of the Cell Cycle in Onion Root Tip Cells

Part 2-Animal Cells
Procedure:

1.Take a prepared slide of whitefish mitosis and observe it under a suitable power. Move the slide around until you have an area that you can count out about 100 cells (approximately). Notice if the cells are:

a) Dividing (chromosomes visible, no nucleus)
b) Not dividing (nucleus visible, no chromosomes).
Fill in the following table:
|Out of about 100 cells: | |Number of Dividing Cells |Number of Cells Not Dividing | | | | | | |

At any one time are most cells dividing or not-dividing? ___________________________

2.Now, go to a computer, log on and look at the...
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