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DNA AND CHROMOSOMES
Differences in DNA
Prokaryotic cells Eukaryotic cells
No true nucleus True nucleus
No chromosomes DNA combines with proteins to form
Circular DNA chromosomes located inside the
No associated proteins nucleus



Chromosome structure
Chromosomes are only visible as distinct structures when a cell is dividing.
Chromosomes appear as…

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The chromosome number for a given species is always constant. In the nucleus of
the somatic (body) cells in eukaryotes the chromosomes occur in homologous
pairs ­ the cells are DIPLOID (2n/ in pairs)
Gametes are HAPLOID ­they contain HALF the normal number of chromosomes
(e.g. sperm and egg)


The…

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Mitosis is the division of the nucleus of a cell that results in each of the daughter
cells having an exact copy of the DNA of the parent cell except the rare event of
mutation.

Mitosis is involed in:
· GROWTH ­ an increase in size through the division of…

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The cell cycle
Three stages of cell cycle:

INTERPHASE- which occupies most of the cell cycle. It is divided into
three parts
NUCLEAR DIVISION- when the nucleus divides into two (mitosis) or four
(meiosis)
CELL DIVISION- process by which the whole cell divides into two or four




Cancer

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Cancer is a group of diseases caused by growth disorder of cells. It
is caused by damage to the genes which regulates mitosis and the
cell cycle.
Cancer treatment
Cancer is treated by blocking the cell cycle to prevent the uncontrolled cell
division.

Chemotherapy involves drugs which disrupts cell cycle:…

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