root tip experiment

• 1. cut 5mm of a root tip from an onion → this is where mitosis occurs in the root
• 2. soak the root tip in warm HCl acid in a water bath of 60 °C to control temp → this breaks down the middle lamella in the root tip
• 3. add a few drops of toluidine blue stain → this highlights the components of the cells and enhances contrast
• 4. gently break root tip apart on a microscope slide and gently flatten → to make it one cell thick so more light can pass through
• 5. place under a microscope and observe the number of cells undergoing mitosis → calculate mitotic index number of cells with visible chromosomes ÷ total number of cells