ONION ROOT TIPS AND THE CELL CYCLE
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?
20%2. What percent were in mitosis?
100% All of the cells are in different stages of mitosis.3. Which phase of mitosis takes the longest?
Interphase
4. During which stage is the nucleolus visible as a dark spot?
Prophase5. How can you recognize a cell in metaphase?
It doesn't seem as dark as prophase; It's much lighter and looks like it's beginning to separate.6. How might you figure out how long (in minutes and/or seconds) each phase of the cell cycle takes based on the data from these onion root cells? Explain your logic and show your calculations and results below.
7. Produce a pie chart in Create-a-Graph that shows the relative lengths of each stage of the cell cycle in these cells including interphase and each stage of mitosis. You can embed the graph here.
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?
20%2. What percent were in mitosis?
100% All of the cells are in different stages of mitosis.3. Which phase of mitosis takes the longest?
Interphase
4. During which stage is the nucleolus visible as a dark spot?
Prophase5. How can you recognize a cell in metaphase?
It doesn't seem as dark as prophase; It's much lighter and looks like it's beginning to separate.6. How might you figure out how long (in minutes and/or seconds) each phase of the cell cycle takes based on the data from these onion root cells? Explain your logic and show your calculations and results below.
7. Produce a pie chart in Create-a-Graph that shows the relative lengths of each stage of the cell cycle in these cells including interphase and each stage of mitosis. You can embed the graph here.
| Interphase | Prophase | Metaphase | Anaphase | Telophase | ||
| Number of Cells |  20 | 10 | 3 | 2 | 1 | 36 |
| Percentage | 55.55% | 28% | 8.33% | 5.56% | 2.78% | 100% |
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