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Stages of Cell Cycle
· The cell cycle is the series of events that take place in a cell leading
to its division & duplication (replication).
· Cell cycle has three stages ­ interphase, nuclear division &
· Interphase ­ the period in the cell cycle when the cell is not
- First growth (G1) phase during which the cell synthesizes the
proteins required for synthesizing cell organelles
- Synthesis (S) phase during which DNA is replicated
- Second growth (G2) phase when organelles grow and divide and
energy stores are increased
· Nuclear division (karyokinesis) when the nucleus divides either into
two (mitosis) or four (meiosis).
· Cell division (cytokinesis) during which the whole cell divides.…read more

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A mammalian cell takes about 24 hours to complete a cell cycle, of
which about 90 per cent is interphase.
Interphase is referred to as the resting phase. But it is a misnomer.
Interphase in the cell life cycle is a period where the cell carries out its
typical functions in preparation for cell division. It is inaccurate to say
that it is 'resting' because it is still producing energy and using DNA
replication to prepare for Mitosis.…read more

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How does cancer & its treatment relate to the cell cycle?
· A group of diseases caused by an uncontrolled division of abnormal
cells in a part of the body.
· It is a result of damage to the genes that regulate mitosis & cell
cycle. This leads to uncontrolled growth of cells.
· As a consequence, a group of abnormal cells, called a tumour,
develops and constantly expands in size.
· Cancers can develop in any organ of the body but are most
commonly found in the lungs, prostate gland, breast & ovaries, large
intestine, stomach, oesophagus and pancreas.…read more

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Treatment of Cancer
· Treatment of cancer involves blocking some part of cell cycle. In this
way, the cell cycle is disrupted & cell division (cancer growth) ceases.
· Chemotherapy ­ treatment of cancer using chemicals (drugs)
· Drugs used to treat cancer disrupt the cell cycle by
- preventing DNA replication, eg. Cisplatin
- inhibiting the metaphase stage of mitosis by interfering with spindle
formation, eg. vinca alkaloids.
· The problem with such drugs is that they also disrupt cell cycle of
normal cells. However, the drugs are more effective against rapidly
dividing cells. As cancer cells have a particularly fast rate of division,
they are damaged to a greater degree than normal cells.
· Some normal body cells that divide rapidly (hair-producing cells) are
also vulnerable to damage. This explains the hair loss frequently seen
in patients undergoing cancer treatment.…read more


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