Onion Root Tips and The Cell-Cycle Webquest

At the beginning of this new semester in biology we have started to learn about Mitosis. To give us a general idea on how to identify the different phase of a cell dividing.

In this activity, you will calculate the lengths of the various phases of the cell cycle in an onion root tip. First you will view some slides and graphics of onion root tips provided by the Molecular Expressions Photo Gallery. Then you will complete the online activity provided by the Biology Project at the University of Arizona.

Part 1.

Use your browser to go to Molecular Expressions Photo Gallery: Mitosis

http://www.microscopy.fsu.edu/micro/gallery/mitosis/mitosis.html

Notice in the micrograph at the top of the page that there are cells in a variety of stages. View the onion slides in this section, then click on "mitosis" in the sentence "Learn the steps in mitosis ... " This will take you to a Java tutorial.  Keep in mind what you have learned here as you proceed to the second part of the activity.

Part 2.

Use your browser to go to Online Onion Root Tips at

http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/assignment.html

Begin by reading the description of the five major cell phases. You will need to keep this information in mind during the activity.

Make a copy of the data sheet that appears on the second page. You will need it to answer the questions.

Proceed through the activity, identifying the phase for each cell you are shown. Pay attention to the hints if you misidentify a cell at first.

When you have completed the activity, answer the following questions:

1. What percent of cells were in interphase?

            A: 55%

2. What percent were in mitosis?

            A: 13%

3. Which phase of mitosis takes the longest?

            A: Interphase

4. During which stage is the nucleolus visible as a dark spot?

A: Interphase is when a dark spot is visible in the nucleolus

5. How can you recognize a cell in metaphase?

            A: When the sister chromosomes bond and are lined up

	Interphase	Prophase	Metaphase	Anaphase	Telophase	Total
Number of Cells	20	10	3	2	1	36
Percent of Cells	55%	27%	8%	5%	2%	100%

 After my partner and I were done working on categorizing cells we had to count them up and place the number in each category. For Interphase we had 20 cells, Prophase we had 10 cells, Metaphase we had 3 cells, Anaphase we had 2 cells and finally for Telophase we had one cell. The percentages below the numbers we got from dividing the number of cells by the total. The one with the highest percentage was Interphase with 55% and the lowest was Telophase with 2%.