Mitosis Write-Up

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Mitosis: (onion roots)
Root cells are good for observing mitosis; this is because they're in the tip of the root which is an area of the plant that grows quickly. This results in more cells going through mitosis all at once, also allowing us to examine the different stages of mitosis.

Stages:

1. Interphase: DNA replicates, but has not formed the condensed structure. They remain as loosely coiled chromatin. The nucleus is still intact.

2. Prophase: The DNA molecules progressively shorten and condense by coiling, to form chromosomes. The spindle fibres are pulled to opposite sides/poles of the cell.

3. Metaphase: The spindle fibres attach themselves to the centromeres of the chromosomes.

4. Anaphase: The spindle fibres shorten and the centromere splits, separated sister chromatids are pulled along behind the centromeres.

5. Telophase: The chromosomes reach the poles of their respective spindles. Nuclear envelope reform before the chromosomes uncoil. The spindle fibres disintegrate.

Method/Procedure:

1. Place some premixed 1 molar Hydrochloric acid and Acetic Orcein in the watch glass. Be careful not to get this mixture on your skin or clothing.

* Hydrochloric acid (HCL) breaks down the middle lamella and softens the cells tissue and the cell will lose its 3-D shape.

2. In to this mixture place the terminal (end) 3 or 4 mm of a garlic root (remove the rest of the root).

* The cut end needs to be removed in order to avoid random errors.

3. Place on the 40oC heating blocks to warm. In a short time (a few minutes) the root tip will feel soft when touched with a mounted needle (Do not let it dry out completely).

* Heat it in order to speed up the process of the cell wall breaking down, and also for the stain to spread quicker. The stain will bind with the DNA, and it will become more visible.

4. Now, using forceps or the mounted needle, pick up the softened root tip and transfer it in to a...
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