| 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
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– 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
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– Nuclear envelope gone
– Kinetochores form at centromere of each chromatid – 2 types of microtubules form and go into nuclear area
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| Metaphase (middle) | Anaphase (seperation) | Telophase (restoration) and Cytokinesis |
| – Chromosomes line up at metaphase plane (equidistant between spindles two poles)
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– Shortest stage
– Sister chromatids become individual chromosomes when cohesion proteins are cleaved → are reeled to opposite poles as microtubules shorten by uncoupling tubulin units
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– 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
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Cytokinesis
- 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:
- Asexual Reproduction: only unicellular organism
- Growth and development: get bigger by adding more cells
- Tissue repair: replace old cells, injuries to a cell can be repaired by replicating the cell in a healthy form