Required Practical 2 - Investigating Mitosis

Required Practical 2 - Investigating Mitosis

• Preparing a root tip cell squash
• Add some 1M HCl to a boiling tube - just enough to cover the root tip, and put the tube in a water bath at 60 degrees Celsius.
• Use a scalpel to cut 1 cm from the tip of a growing root.
• Transfer the root tip into the boiling tube containing the acid and incubate for approx. 5 mins
• Use tweezers to remove the root tip from the tube and use a pipette to rinse it with cold water. Leave the tip to dry on a paper towel.
• Place the tip on a microscope slide and cut 2 mm from the very top of it, discard the rest.
• Use a mounted needle to break the tip open and spread cells out thinly.
• Add a few drops of stain and leave for a few minutes.
• Place a cover slip over the cells and put a piece of folder filter paper on top. Push down firmly to squash the tissue.

Using an optical microscope

• Clip prepared slide onto the stage
• Select the lowest powered objective lens.
• Use the coarse adjustment knob to move the objective lens down to just above the slide.
• Look down the eyepiece and adjust the focus with the fine adjustment knob, until you get a clear image of what's on the slide.
• If the magnification isn't strong enough swap to a higher powered objective lens and refocus.

Mitotic Index

• Mitotic Index = number of cells with visible chromosomes
• total number of cells observed