Core Practical 6: Observing the Stages of Mitosis (Edexcel International A Level Biology) : Revision Note
Observing the Stages of Mitosis
Growth in plants occurs in specific regions called meristems
The root tip meristem can be used to study mitosis
The root tip meristem can be found just behind the protective root cap
In the root tip meristem, there is a zone of cell division that contains cells undergoing mitosis
Pre-prepared slides of root tips can be studied or temporary slides can be prepared using the squash technique (root tips are stained and then gently squashed, spreading the cells out into a thin sheet and allowing individual cells undergoing mitosis to be clearly seen)

A micrograph of a stained root tip, nuclei are clearly visible
Apparatus
Roots of onion or garlic
Microscope slide
Cover skip
1 M hydrochloric acid
Stain (acetic orcein, toluidine blue for example)
Paper towel
Scalpel blade
Cutting tile
Water bath at 60oC
Boiling tube
Optical microscope
Method
Garlic or onion (Allium cepa) root tips are most commonly used (the bulbs can be encouraged to grow roots by suspending them over water for a week or two)
Prepare a boiling tube of 1M hydrochloric acid and place in a water bath at 60oC for 10 minutes
Remove the tips of the roots (about 1cm) and place in the warmed hydrochloric acid for 5 minutes
Rinse the tips well in cold water using a pipette and blot dry with a paper towel
Cut approximately 2mm off the tip and place onto a microscope slide
Add a drop of a suitable stain (eg. warm, acetic orcein, which stains chromosomes a deep purple)
The stained root tip is gently squashed on a glass slide using a blunt instrument (eg. the handle of a mounting needle or a cover slip using your fist to gently apply pressure in a rolling motion)
View the slide under the microscope
Cells undergoing mitosis (similar to those in the images below) can be seen and drawn
Annotations can then be added to these drawings to show the different stages of mitosis
Results
You should be able to observe cells in different stages of mitosis from the stained meristem

Micrograph of cells from a meristem showing cells in prophase (P)

Micrograph of cells undergoing metaphase (M) and anaphase (A)
You've read 0 of your 5 free revision notes this week
Sign up now. It’s free!
Did this page help you?