Mitosis

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Mitosis is a process where the cell divides and the daughter cells have the same number of chromosomes with the parent cell. Mitosis occur in somatic cells. Mitosis plays an role in growth, repair damage cells and asexual reproduction.

Mitosis consists of 4 stages:

  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase and Cytokinesis

Prophase

Prophase eukaryotic mitosis

Early prophase

  •  Chromatin fibres become more tighly coiled.
  • Nucleoli and nucleus membrane disappear.
  • Each duplicated chromosome appers having two sister chromatids.
  • The mitotic spindles begin to form. It is made of microtubules radiating from two centrosomes.
  • Centrosomes move away from each other.

Late prophase

  • Nuclear envelope disintegrates.
  • Microtubules enter nucleus and attach the chromosomes, which have been condensed.
  • The contraction of spindle microtubules moves the chromosomes to the middle of the cells.

 

Metaphase

Metaphase eukaryotic mitosis

  • Centrosomes are now at the opposite of the cell.
  • Chromosomes assemble on the metaphase plate (equatorial line).
  • Centromeres of all chromosomes are aligned with one another and the sister chromatids of each chromosome straddle the metaphase plate.
  • For each chromosome, the centromeres are attached to microtubules coming from the opposite of cell.

 

Anaphase

Anaphase eukaryotic mitosis

  • Begins when the paired centromere of each chromosome separate, finally form the sister chromatids from each other.
  • Chromosomes move towards the opposite poles of the cell.
  • Chromosome moves the centromere first. At the same time, the poles of cell move further apart, elongating the cell.

 

Telophase

Telophase eukaryotic mitosis
Cytokinesis eukaryotic mitosis

  • The daughter nuclei form at the two poles of cell.
  • Nuclear envelope form.
  • Chromatin becomes less tightly coiled.
  • Cytokinesis occurs to separate the cell into two daughter cells with genetically identical nuclei.