Mitosis is the phase of the cell cycle where the nucleus of a cell is divided into two nuclei with an equal amount of genetic material in both the daughter nuclei.
It succeeds the G2 phase and is succeeded by cytoplasmic division after the separation of the nucleus.
Mitosis involves two processes: karyokinesis (nuclear division) and cytokinesis (cytoplasmic division).
Karyokinesis is a continuous process but for the sake of convenience is divided into four phases. The phases are prophase, metaphase, anaphase and telophase.
Prophase is the first and longest phase of mitosis.
Prophase:
Prophase immediately follows S and G2 phase of the cycle and is marked by condensation of the genetic material to form compact mitotic chromosomes composed of two chromatids attached at the centromere.
The completion of prophase is characterized by the initiation of the assembly of the mitotic spindle, the microtubules and the proteinaceous components of cytoplasm that help in the process.