Cell Mitosis Simulator (2D)

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Cell grows and duplicates its DNA; chromatin is loose and uncondensed.

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Chromatids separated

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How it works

Mitosis divides one diploid cell into two genetically identical daughter cells, each keeping the same chromosome number (2n). The cell shown here has 4 chromosome pairs (8 chromatids once duplicated) as a simplified stand-in for a real karyotype.

Interphase — the cell grows (G1), copies its entire genome (S phase) so every chromosome now consists of two identical sister chromatids joined at a centromere, then prepares division machinery (G2). Chromatin stays decondensed and diffuse.
Prophase — chromatin coils tightly into visible X-shaped chromosomes; the nuclear envelope breaks down; centrosomes migrate to opposite poles and begin nucleating spindle microtubules.
Metaphase — spindle fibers attach to each chromosome's kinetochore and align all chromosomes along the metaphase plate, the cell's equator — a checkpoint confirms every chromosome is properly attached before anaphase begins.
Anaphase — the centromere splits and motor proteins shorten the spindle fibers, pulling sister chromatids apart to opposite poles as independent chromosomes.
Telophase — two new nuclear envelopes reform around each chromosome set, chromosomes decondense back into chromatin, and the spindle disassembles.
Cytokinesis — in animal cells, a contractile ring of actin and myosin pinches the cytoplasm along a cleavage furrow, splitting one cell into two independent daughter cells.

Interphase

Chromosome pair 1 Chromosome pair 2 Chromosome pair 3 Chromosome pair 4