Mitosis
 (from http://www.sc2000.net/~czaremba/labs/mitosis.html)
Mitosis is considered nuclear division, since its main stages deal strictly with the nucleus and its contents (DNA). Mitosis consists of 4 major stages: Prophase, Metaphase, Anaphase, and Telophase. Mitosis is part of a larger process called the cell cycle. When a living organism needs new cells to repair damage, grow, or just maintain its condition, cells undergo the cell cycle. In this lab you are going to determine the approximate time it takes for a cell to pass through each of the four stages of mitosis. You may use your textbook and class notes to help you identify the stages of mitosis as seen under the microscope.
 
Materials:
Microscope
Prepared slide (Onion root tip)
Lab Paper
 
Procedure:
 
1. Set up a compound light microscope and turn on the light .
 
2. Place a slide containing a stained preparation of the onion root tip.
 
3. Locate the meristematic zone, which is just above the root cap at the very end of the tip.
 
4. Focus in on low power and then switch to medium or high power. Below find micrographs of the four stages of mitosis. Use them to help you identify the stages on the microscope slide.
 
 
Prophase
 

Metaphase
 

Anaphase
 

Telophase
 
5. Now count the number of cells found in each stage of mitosis and the cells in the interphase stage and place the data in the chart below.
 
6. Determine the percentage of time each cell will spend in each stage of mitosis. Divide the number of each cell by the total number of cells and multiply by 100 to determine the percentage. Place these values in your journal: (Sample Table below)
 

Stage of Mitosis

Number of Cells

Percent of time in each stage

Interphase

 

_____________%

Prophase

____________________________________________

_____________%

Metaphase

____________________________________________

____________%

Anaphase

____________________________________________

____________%

Telophase

____________________________________________

____________%

Total number of Cells

____________________________________________

100%

 
7. Make a bar graph of the data you have just collected and then answer the questions that follow. Make a descriptive title and label the axes appropriately.

 

 

Post-lab questions: (answer in your journal)

1. Of the four stages of mitosis, which phase takes the most time to complete (in %)?

2. Which phase is the shortest stage in duration (in %)?

3. What would happen if the process of mitosis skipped metaphase?

4. Why are cell cycle checkpoints so important during cell cycle, what are the checkpoints trying to prevent?

5. What is the relationship between the protein p53 and cells becoming cancerous?