This simulation animates mitosis, the process by which a eukaryotic cell divides its duplicated chromosomes into two identical daughter cells. It steps through all five phases in sequence — prophase, prometaphase, metaphase, anaphase and telophase — each lasting 300 animation frames, played at a speed you control. Eight chromosomes (four homologous pairs) condense, align at the cell's equator on spindle fibres radiating from two centrosomes, and are then pulled apart before a cleavage furrow splits the cell in two. The isometric canvas view redraws every frame using eased interpolation, so chromosome and cell-shape transitions look smooth rather than robotic.
The full mitotic cycle of a single cell: chromatin condensing into 8 X-shaped chromosomes, centrosomes migrating to opposite poles, spindle fibres attaching to kinetochores, chromosomes lining up at the metaphase plate, sister chromatids separating into 16 chromatids pulled toward the poles, and finally a cleavage furrow dividing one cell into two daughter cells, each with a full 2n chromosome set.
Use the Speed slider (0.2×–4×) to slow down or speed up the animation, and Cell size (0.5×–1.5×) to rescale the cell. Jump directly to any phase — Prophase, Pro-meta, Metaphase, Anaphase or Telophase — with the phase buttons, or let it play continuously. Pause/Play and Restart controls sit below the phase buttons, and the live stat panel tracks phase name, progress percentage, chromosome count, DNA content and number of cells in real time.
Mitosis produces two genetically identical daughter cells, each with the same number of chromosomes as the parent — in this simulation, 8 chromosomes condense, are copied, and separate into two sets of 8 chromatids. This is fundamentally different from meiosis, which halves the chromosome number to produce sperm and egg cells with only 4 chromosomes each.
The simulation animates prophase (chromatin condenses into visible chromosomes and centrosomes migrate to opposite poles), prometaphase (the nuclear envelope breaks down and spindle fibres attach to kinetochores), metaphase (all chromosomes align at the cell's equator, the metaphase plate), anaphase (sister chromatids separate and are pulled to opposite poles while the cell elongates), and telophase (nuclear envelopes reform, chromosomes decondense, and the cleavage furrow deepens into two daughter cells).
The Speed slider scales how many animation frames advance per tick, ranging from 0.2× (very slow, good for study) up to 4× (fast overview) of the base rate. Each of the five phases lasts 300 frames at 1× speed before advancing to the next. The Cell size slider rescales the drawn radius of the cell and its chromosomes from 0.5× to 1.5×, purely visual and independent of timing.
Each drawn chromosome represents a duplicated chromosome made of two sister chromatids joined at a centromere, which is the classic X shape seen in textbook diagrams during condensation. In the simulation this shape is drawn with two crossing line pairs whose thickness grows as the "condensed" value increases during prophase, visually representing chromatin packing tighter into a compact chromosome.
The simulation tracks 8 chromosomes throughout prophase, prometaphase and metaphase (labelled 4n DNA content, since each chromosome is duplicated). During anaphase the 16 sister chromatids separate and are relabelled as moving toward two poles. By telophase each forming daughter cell ends up with its own set of 8 chromosomes (2n), so one parent cell with 4n content produces two daughter cells that are each back to the normal 2n content.
Yes — the four phase-jump buttons (Prophase, Pro-meta, Metaphase, Anaphase, Telophase) set the internal animation clock directly to the start of that phase, skipping ahead without needing to wait through earlier phases. You can combine this with Pause to freeze on a single phase for closer inspection, or with the Speed slider to replay just that phase slowly.