Biology · Mitosis · Onion root tip

Identifying mitosis stages

A field of view from a squashed onion root tip stained with aceto-orcein. Each cell is caught at a different stage of the cell cycle. Click each cell and choose the stage. Once all 24 are classified, calculate the mitotic index.

Inter

Pro

Meta

Ana

Telo

Stage guide

Interphase

Chromatin spread out as fine threads; nucleus clearly visible.

Prophase

Chromosomes condensed and visible; nuclear membrane breaks down.

Metaphase

Chromosomes line up across the centre of the cell.

Anaphase

Chromatids pulled apart, moving to opposite poles.

Telophase

Two new nuclei reform; chromosomes decondense; cell starts dividing.