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Prokaryotic cells—bacteria and archaea—lack a nucleus and undergo binary fission, a simple division of their circular DNA. In contrast, eukaryotic cells—found in animals, plants, and fungi—contain multiple linear chromosomes that are packaged into chromatin.
In humans, DNA is organized into 46 chromosomes. These chromosomes are integral to the cell cycle, which comprises the G1, S, and G2 phases of interphase followed by the M phase, which includes mitosis and cytokinesis.
Mitosis is traditionally divided into four phases: prophase, metaphase, anaphase, and telophase. Some texts add prometaphase between prophase and metaphase.
Prophase – Chromosomes condense into distinct structures, and the mitotic spindle assembles at opposite poles.
Metaphase – Condensed chromosomes line up at the metaphase plate.
Anaphase – Sister chromatids separate at the centromeres and are pulled toward opposite poles. Cytokinesis often initiates during this phase.
Telophase – Chromosomes decondense, nuclear envelopes re‑form around each chromosome set, and nucleoli re‑appear.
Late telophase marks the culmination of nuclear re‑assembly: two complete nuclei emerge, each surrounded by a new nuclear membrane. Simultaneously, cytokinesis—the physical division of the cytoplasm—advances. The two processes overlap; distinguishing a strict boundary is often impractical.
Cytokinesis begins in anaphase with the formation of a cleavage furrow, driven by a contractile ring composed of actin and myosin. As the ring contracts, the furrow deepens, eventually bisecting the cell once the new nuclear envelopes are fully formed.
In short, telophase is the final step that restores nuclear integrity, while cytokinesis completes the separation of the cell into two independent daughters.
