G2 of Interphase Prophase (condensation) Prometaphase
The last part of interphase:

– A nuclear envelope encloses the nucleus.

– Nucleoli usually present in nucleus

– Two centrosomes have formed by duplication

–          Each centrosomes contain two centrioles

– duplicated chromosomes but not condensed/visible

– Nucleoli gone, nuclear envelope thinning

– Chromatin fibers condense into tightly coiled and visible chromosomes

– Mitotic spindle begins to form by adding tubulin units to microtubules

– Centrosomes move away by lengthening microtubules  



– Nuclear envelope gone

– Kinetochores form at centromere of each chromatid

– 2 types of microtubules form and go into nuclear area







Metaphase (middle) Anaphase (seperation) Telophase (restoration) and Cytokinesis
– Chromosomes line up at metaphase plane (equidistant between spindles two poles)

– Shortest stage

– Sister chromatids become individual chromosomes when cohesion proteins are cleaved → are reeled to opposite poles as microtubules shorten by uncoupling tubulin units

– Two daughter nucleoli form  from parent fragments and endomembrane system; one at each pole 

– chromo decondense & become chromatin, microtubules depolymerize

– nucleoli & envelope reappears

cleavage furrow begins to separate the two into sister cells


  • Animal cells: carry out cytokinesis by forming a cleavage furrow: groove that forms as purse strings are tightened
    • Actin filaments (microfilaments) form a ring inside plasma membrane between two nuclei → microfilaments shorten → stimulate cell contraction that causes cell to pinch inwards until divides

  • Plants cells: cell wall too rigid so can’t pinch inward, instead vesicles from golgi move to middle and make a cell plate which fuses with cell membrane and produces 2 daughter cells

Mitosis Function:

  1. Asexual Reproduction: only unicellular organism
  2. Growth and development: get bigger by adding more cells
  3. Tissue repair: replace old cells, injuries to a cell can be repaired by replicating the cell in a healthy form