The cell cycle has three main stages:
1. Interphase — the cell grows, organelles increase, DNA replicates
2. Mitosis — the nucleus divides into two identical nuclei
3. Cytokinesis — the cytoplasm divides, producing two genetically identical daughter cells
Mitosis is used for growth, repair, and asexual reproduction. It produces diploid cells.
Cancer occurs when cells divide uncontrollably due to changes (mutations) in genes that regulate the cell cycle. This leads to a tumour — benign tumours do not spread, malignant tumours invade surrounding tissues.