Checkpoint Controlling Process Through the Mitosis Portion of the Cell Cycle.

1
Checkpoint Controlling Process Through the
Mitosis Portion of the Cell Cycle.
Progress trough the cell cycle is regulated by a
series of checkpoint controls that slow or
arrest the cell cycle until the event(s) being
monitored are completed.The first mitosis
checkpoint controls nuclear envelope breakdown
and thus entry into prometaphasewhich represent
the first point of no return during mitosis.This
checkpoint is likely related to the RAD 9
checkpoint that arrest the cell cycle in response
to DNA damage.
2
Lung Cell in very early anaphase (left)A similar
cell in mid to late anaphase( right).At the time
of nuclear envelop breakdown each replicated
chromosome posses two sister kinetochores that
are positioned on opposite sides of the
chromosome.
3
Hermit the NEWT Photomicrographs of living and
dividing new lung cell. Below Rat Kangaroo
kidney cells
4
Electron microscopic and light microscopic microgr
aphs from the Kinetochor (large arrow) the
centrosome region(small arrow) of the mitotic
cells.
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CENTROSOMES

• Two centrosome forming radial arrays of
  microtubules (newt lung cell) right.
• Centrosome (electromicrograph) left.

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Centrosome

• Centrosome replicated nearly of DNA sytnhetis
  when chromosomes replicated.
• Controlled because too few too many can lead to
  monopolar or multipolar spindle.