Cell division

Cell cycle:
Interphase
Nuclear division (PMAT)

• Prophase
• Metaphase
• Anaphase
• Telophase

Cytokinesis

Interphase
Longest period(G1, S, G2)

• DNA duplication occur
• chromatid start to condense to form chromosome
• spindle apparatus starts to form

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Mitosis
Prophase
longest state in nuclear division

• chromosome shorten, thicken and become visible
• centriole move to the opposite and become aster as microtubules(spindle fibre) develop
• nuclear membrane and nucleoli disintegrate and disappear

Metaphase

• Spindle well formed
• chromosome are linked to the spindle at centromere
• they arrange along the equator.

Anaphase

• centromere duplicates
• two members of each pair of chromatids separate and drawn to opposite pole by contraction of spindle fibre
• sister chromatids become daughter chromosome
  

Telophase

• daughter chromosome uncoil, lengthen and revert to the invisible interphase conformaion.
• Nuclear membrane reforms
• nucleoli become apparent
• spindle fibres degenerate and disappear

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Meiosis
Meiosis I
Prophase I

1. Early prophase I: shorten, thicken, visible+densly stained granule chromomere appear
2. Mid prohase I: pairing of homologous chromosome =synasis, forming bivalent
3. Late prohase I: (a)tetrad apparent in each bivalent
   -----------------(b)non sister chromatid form cross-shape
   -------------------structure called chiasmata, the process
   -------------------involve recombination of genetic material
   -------------------called crossing over(to be discussed later)

And also other change in prophase of mitosis.

Metaphase I, Anaphase I and Telophase I are similar to that in mitosis except the seperation is done on chromosome instead of sister chromatid.

Cytokinesis
Animal only, proceed to meiosis II imediately in plant

Meiosis II
The process of meiosis II is the same as mitosis except there is no replication of DNA occur( S phase in interphase does not exist)
Interphase-->Prophase II-->......
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Cytokinesis
Division of cytoplasm
1. animal cell
Furrow form. It deepens and eventually cleaves the cell into two daughter cell.
Furrow appears at the spindle equator so that two daughter cells will have an equal division of cytoplasm and genetic material.

2. plant cell
Cell plate of pectin form in the equatorial region.
It glows until it reaches the edges of the cell and fused with the cell membrane.
Two adjacent daughter cells form.
Strengthening material is laid down on both sides of the cell plate and the cell plate becomes a layer called middle lamina between two newly formed cell

**Centriole, Aster are absent in plant cell division