A-Level Biology Technician Guide: Identifying Stages of Mitosis Under a Microscope

Mitosis looks simple on paper: prophase, metaphase, anaphase and telophase. In practice, finding clear examples isn't always so straightforward.

Most cells will be in interphase, with only a few showing obvious stages of mitosis. Students may also find unclear cells and ask, “Is this right?”, which is completely normal.

Always have a backup

A prepared slide is worth having on hand for this practical. It gives you a reliable reference if the student root tip squash doesn't go to plan, and lets you show students exactly what they're looking for.

The Allium Root Tip – Stained for Mitosis (BB1238) provides clear, high-contrast chromosomes and multiple stages in one slide.

Use it for a quick demonstration before students attempt their own slides.

Root tip squash: the basics

The student-prepared slide is a useful opportunity to show that real practical work isn't always as neat as a textbook image.

The basic preparation involves:

A few common problems can make the results difficult to interpret: slides may be too thick, staining may be poor, or students may simply be looking in the wrong area.

1. Grow the roots – Place an onion so that the roots can grow into water. Leave until the roots are a few centimetres long.
2. Cut the root tip – Remove approximately 1 cm from the end of a healthy root.
3. Soften the tissue – Treat the root tip with HCl according to your school's established practical protocol.
4. Stain the chromosomes – Transfer the root tip to the appropriate stain and leave for the recommended time.
5. Mount the sample – Place the stained root tip on a microscope slide and add a coverslip.
6. Squash the root tip – Press down firmly and vertically on the coverslip to spread the cells into a thin layer. Take care not to move the coverslip sideways.
7. View under the microscope – Start on low power to locate a suitable area, then increase the magnification to look for condensed chromosomes and identify the stages of mitosis.

Always follow your school's approved method, chemical concentrations and safety procedures for the HCl and stain being used.

A few common problems can make the results difficult to interpret: slides may be too thick, staining may be poor, or students may simply be looking in the wrong area.

A quick pre-check, a good demonstration slide and a few spares can make the lesson run much more smoothly.

A good slide won't help much if the microscope isn't up to the job.

Students should start on low power, find a suitable area and then move to higher magnification. Encourage them to look for condensed chromosomes, rather than simply looking for nuclei.

If your microscopes need an upgrade, options include the Budget Buster Microscope (MIC5740), the Microscope with Mechanical Stage (MIC6618) for easier slide movement, or the Binocular Microscope (MIC8014) for a more comfortable viewing experience.

Make it easier with a microscope camera

A Microscope Camera (MIC4320) can be particularly useful for this practical. Project a prepared BB1238 slide onto the board and show students what each stage looks like before they start.

They can then compare their own slides with a known good example.

Technician checklist:

The aim isn't for every student slide to be perfect. Showing students the difference between a clear prepared specimen and a real student result is part of the practical learning — and that's where technicians can make a real difference.