Study of Mitosis Using Onion Root Tip

 Study of Mitosis Using Onion Root Tip 
Objective: To observe and identify the stages of mitosis in the onion root tip cells and  understand the cell division process. 
Introduction: 
Mitosis is a process of cell division that results in two genetically identical daughter cells from a  single parent cell. The onion root tip is a commonly used specimen for studying mitosis because  it has a high rate of cell division. The root tip provides an ideal site to observe the various stages  of mitosis due to the continuous growth of root cells. 
Materials and Reagents: 
1. Fresh Onion (Allium cepa) root tip
2. Microscope Slides and Coverslips 
3. Microscope 
4. Staining Solution: (e.g., Aceto-orcein/Toluidine Blue O/Acetocarmine)
5. Acetic Acid (for fixing) 
6. 0.1 N Hydrochloric Acid (for hydrolysis) 
7. Pipettes, Needle and Dropper 
8. Distilled Water 
9. Scalpel or Blade 
10. Forceps 
11. Watch glass
Procedure: 
1. Preparation of the Onion Root Tip: 
1. Harvesting: Cut a few millimeters from the tip of an onion root. The root tip should be  freshly obtained to ensure active cell division. 
2. Fixation: Place the root tip in a vial with a fixative solution (e.g., a mixture of glacial acetic acid  and ethanol, 1:3) for about 10-15 minutes to preserve the cells.
3. Hydrolysis (Optional): If using a staining method that requires hydrolysis, immerse the  fixed root tip in 0.1 N Hydrochloric acid at 60°C for 5-10 minutes to soften the tissues.
4. Staining: Stain the root tip using a suitable staining solution. Place  the root tip in the staining solution for about 10-15 minutes to enhance the visibility of  chromosomes. 
5. Rinsing: Rinse the stained root tip with distilled water to remove excess stain.
2. Preparing the Slide: 
1. Squashing: Place the stained root tip on a clean microscope slide. Gently use a scalpel or  blade to cut the root tip into smaller pieces if necessary. Add a drop of water or mounting  medium on top of the root tip. 
2. Covering: Place a coverslip over the root tip. Use a gentle tapping technique with the  back of a pencil or a small piece of paper to flatten the root tip without crushing it.
3. Observing Under the Microscope: 
1. Initial Examination: Start with the lowest magnification objective lens (e.g., 4x or 10x)  to locate the root tip and focus on the area of interest. 
2. Fine Focusing: Switch to a higher magnification objective lens (e.g., 40x) to observe the  detailed structure of the cells and the stages of mitosis. 
3. Identifying Stages: 
o Prophase: Look for chromosomes that are condensing and becoming visible, as  well as the formation of the mitotic spindle. 
o Metaphase: Identify chromosomes aligned along the metaphase plate.
o Anaphase: Observe chromosomes being pulled towards opposite poles of the  cell. 
o Telophase: Look for chromosomes de-condensing and the formation of nuclear  membranes around each set of chromosomes. 

 

Results:  

Different stages of mitosis was observed and studied. NB: Include labeled images or drawings of the observed stages of  mitosis. 

Discussion:
∙ Mitosis Rate: Discuss the relative abundance of cells in each stage of mitosis and what  this indicates about the rate of cell division in the onion root tip. 
∙ Comparison: Compare the stages of mitosis observed with textbook diagrams or other  sources to confirm accuracy. 
∙ Staining Effectiveness: Evaluate how well the staining method worked for visualizing  the chromosomes and overall cell structure. 
Conclusion: 
The study of mitosis using onion root tip cells provides a clear and accessible way to observe the  stages of cell division. By following the procedure and analyzing the results, one can gain a  better understanding of the mitotic process and its role in growth and development.