Practical 5: Observing stages of mitosis

Question 1

Observing stages of mitosis

Answer 1

1. Cut a 5mm sample of the root tip using a scalpel.
2. Transfer root tip to sample tubes containing HCl and leave for 5 minutes.
3. Transfer to watch glass containing cold distilled water. Leave for 5 minutes.
4. Dry root tips on filter paper.
5. Place tip on a microscope slide. Macerate with a needle to spread the cells out.
   This makes the chromosomes visible and will therefore show which cells are
   undergoing mitosis.
6. Add a drop of toluidine blue to the slide and leave to stain for 2 minutes.
7. Lower the cover slip down carefully onto the slide. Make sure there are no air
   bubbles in the slide which may distort the image, and that the coverslip doesn’t
   slide sideways which could damage the chromosomes.
8. Wrap in a paper towel and gently ‘squash’ the slide.
9. Place under a microscope and set the objective lens on the lowest
   magnification, then use the coarse adjustment knob to move the lens down to
   just above the slide.
   10.Use the fine adjustment knob to carefully re-adjust the focus until the image is
   clear (can use a higher magnification if needed).
   11.To calculate mitotic index, cells undergoing mitosis must be counted (cells
   with chromosomes visible), as well as the total number of cells.

risks- broken glass, hydrochloric acid

variables-
control = size of root tips
independent = N/A
dependent = N/A

plot data by drawing an image observed