Name______Period______Date______
Cell Division in the Root Tip
Procedures
1. Obtain an onion root and cut off the bottom 1 or 2 mm of the root tip and place it on a slide.
2. Add a very small drop of 1M HCL acid to the root tip on the slide and let it sit for 4 min.
3. Using a paper towel soak the HCL away from the root tip.
4. Cover the root tip with a drop of 1% toluidine blue stain and let stand for 2 minutes.
5. After two minutes, blot excess stain and rinse with water until it runs clear. Add one drop of water and gently lay a coverslip over the root tip.
6. On a paper towel, pressure to the coverslip area to squash and spread the root tip tissue.
7. Mount the slide on your microscope.
8. Use the low power objective on your microscope to look for thin layers of cells and then use the 40X power objective to observe mitotic stages in individual cells.
Hypothesis: If the cells located in the onion root tip are frequently dividing, then we should be able to ______.
Illustrations
Control Root tips (Grown in water):
Identify chromosomes at the various stages of mitosis in the water treated root tips. Make sketches of each of the stages of mitosis observed.
Conclusion:
1. Summarize the procedure for this lab.
2. The cells in the root of an onion are actively dividing. How might the numbers of cells found in this region differ from a different part of the plant?
3. What stage were the majority of the cells in the water treated root tips? Explain.
4. What happens when cell division is interrupted?
5. What process must take place before mitosis can begin?
6. Why is mitosis important? Where does mitosis take place?
7. Give an example of cells in your body that divide slowly or do not divide at all.
8. What is cancer? How does cancer affect the rate of mitosis?
9. How would a slide of cancerous cells look different from this one?
10. What type of cells in your body do not divide by mitosis?