CPAC 5: Root tip squash to observe mitosis

• Root tip squash core practical:

  • IV - 5 temps
  • DV - count the no. of cells in mitosis
  • CV - pH of soil, same source , same size root tips (cut with ruler + scalpel)

  Method:

  1. Soak root tips in warm dilute HCl for 5 mins to soften the tissue (stain enter)
  2. Rinse with water
  3. Place tip on microscope slide
  4. Add toluidine blue to stain the chromosomes + make them visible
  5. Put coverslip on top
  6. Gently squash (to produce single layer of cells)
  7. Look at sample under microscope, count no. cells in mitosis
  8. Calculate mitotic index = no. of cells in mitosis/ total no. of cells
  9. T-test
• Why do we soak root tips in HCl?

  • Breaks down middle lamella
  • To produce a thin layer of cells
  • That light can pass through
• Why do we add toludine blue?

  • To make chromosomes visible
  • So we can identify stages of mitosis