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Mitosis
- Cell cycle involves Mitosis and interphase (G1, S,
G2)
- G1 is cell growth phase, S is synthesis, G2
is second growth phase.
- 4 phases of mitosis:
- Prophase:
Chromosomes become visible as two strands (chromatids) held together
by centromere (or kinetochore). Disappearance of nucleolus, replication
of centrioles, disintegration of nuclear envelope.
- Metaphase:
Mitotic spindle becomes organised around centrioles and directs
movement of the chromosomes to the plane in the middle of the cell
(equatorial or metaphase plate)
- Anaphase:
Chromatids separate and pulled to opposite ends of cell by
microtubules attached to centromeres
- Telophase:
Reconstitution of nuclear envelope, chromosomes uncoil, nucleoli
reappear and
- Cytokinesis
cytoplasm divides
- Leaves 2n cells
1.9 THE CELL REPLICATION CYCLE : MITOSIS [Cell
Biol]
| Phases of the cycle; Interphase : G1, S, G2
: M phase |
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| Phases of mitosis: prophase, metaphase,
anaphase, telophase. Cytokinesis. |
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| Cellular organelles distributed equally
between daughter cytoplasms during M phase. |
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| Stem cells (continually dividing), e.g.
skin; other mature cells replicate only after tissue damage, e.g. liver;
or not at all, e.g. neurones. |
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| Control of cell division by extracellular
growth factors. Uncontrolled replication characteristic of cancer cells. |
Anti-cancer drugs often target S-phase in
replicating cells. |
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