01Interphase
Most of a cell's life is interphase: G₁ (growth, normal work), S (DNA replication — each chromosome becomes two sister chromatids), G₂ (prepare for division). Cells that stop dividing enter G₀ (most neurons, muscle cells).
02Mitosis and cytokinesis
Prophase: chromosomes condense, spindle forms. Metaphase: chromosomes line up at the middle. Anaphase: sister chromatids separate to opposite poles. Telophase: nuclei re-form. Cytokinesis splits the cytoplasm — cleavage furrow in animals, cell plate in plants.
Result: two genetically identical diploid daughter cells. Mitosis is for growth, repair and asexual reproduction.
03Notebook box
DNA content per cell: G₁ = 1x → after S = 2x → after cytokinesis = 1x each. Chromosome NUMBER stays the same.
Worked example: A human cell in G₂ has how many chromosomes and chromatids? → 46 chromosomes, 92 chromatids.