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Onion Root Tip Mitosis Experiment Procedure

  • Botany

In this onion root tip mitosis experiment procedure post we have briefly explained about principle, requirements, procedure, expected result and applications.

Onion Root Tip Mitosis Experiment Procedure

Just behind the root cap on the onion root tip is meristematic tissue. This is an excellent resource for learning about onion root tip mitosis stages. The roots can be easily produced if an onion is placed on a water-filled conical flask with the onion disc touching the water, or if the onion is planted on wet sand with the bulb partially covered in sand. 

In two days, roughly 1cm long roots emerged, which we cut, stabilised, and preserved. Longer roots are undesirable because they contain more non-dividing tissue.

Principle

Individual DNA molecules, or chromosomes, contain all of an organism’s genetic information. Eight chromosomes make up an onion cell. In the expanding root tips of sprouting seeds or bulbs, cell division happens quickly. Because the onion root tip is a fast-growing portion of the onion root tip mitosis stages at different levels.

Onion root tips can be prepared and squished in such a way that they can be flattened on a microscopic slide and the chromosomes of individual cells can be easily observed. The highly coiled chromosomes found in onion root tip mitosis stages can be detected using DNA specific stains such as Feulgen stain and Acetocarmine stain.

Requirements

Materials

1. Onion Root Tips

2. 1N HCL

3. 1:3 acetomethanol fixatives

4. 70% and 90% ethanol

5. 2% acetocarmine stain

6. Slide

7. Cover glass

8. Sealing wax or nail polish

9. 45% of acetic acid

Procedure

1. In a specimen tube, fix the freshly cut 1cm long root tips in acetomethanol fixative overnight.  Remove the fixative and replace it with 90% ethanol.

2. Set aside for two hours. Decant 90 percent ethanol; add 70 percent ethanol. The root tips can be preserved for a long time in 70 percent ethanol.

3. It’s even better if the tube is tightly closed and the temperature is kept at 4 degrees Celsius. For 1 minute, soak the root tips in 1N HCL. The cell wall will become softer as a result of this.

4. Take a drop of 45 percent acetic acid drops become coloured, it can be decanted and a fresh 45 percent acetic acid drop is added.

5. Rinse the tips once in water, then transfer to acetocarmine stain and stain for 30 minutes. Place a cover glass on the root tip and squish it between the folds of blotting paper with a rubber end pencil.

6. To prevent the acetic acid film from drying and air bubbles from entering the cover glass, seal the edges with molten wax or nail polish right away. The slide is now ready to be examined under the microscope.

Expected Result

Onion Root Tip Metaphase

Onion root tip mitosis stages experiment procedure: Onion Root Tip Metaphase, Prophase, Anaphase, and Telophase

Onion root tip mitosis stages

Prophase, Metaphase, Anaphase, and Telophase are the four stages onion root tip mitosis stages.

Prophase: The chromosomes super twist, condense, and become visible for the first time during the cell cycle during prophase. The spindle fibres begin to develop. The nuclear membrane begins to break down.

Metaphase: The spindle fibres reach and adhere to the centromere of each sister chromatid during metaphase. The chromosomes align in the cell’s central plane. The nuclear membrane entirely disintegrates.

Anaphase: The centromeres begin to separate and the sister chromatids begin to migrate towards the opposing poles of the cell during anaphase.

Telophase: The chromosomes are grouped on each end of the cell at this stage. The nuclear membrane begins to re-form. Between the two daughter nuclei, the cell plate (new cell wall) begins to develop. After that, cytokinesis will occur.

Onion Root Tip Metaphase

Onion root tip mitosis stages, Prophase, Anaphase, and Telophase

Further Readings

Reference