The Cell Cycle, cell division by mitosis, meiosis, DNA and chromosomes and Homologus chromosomes

A detailed document about the cell cycle, division by mitosis & meiosis, DNA and chromosomes

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  • Created by: sara10
  • Created on: 11-03-13 19:37

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The Cell Cycle

Cells are not static structures, but are created and die. The life of a cell is called the cell
cycle and has four phases:

In different cell types the cell cycle can last from hours to years. For example bacterial
cells can divide every 30 minutes under…

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Mitosis is a type of cell division that produces genetically identical cells. During mitosis
DNA replicates in the parent cell, which divides into two new cells, each containing an
exact copy of the DNA in the parent cell. The only source of genetic variation in the cells
is via mutations.…

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In animal cells a ring of actin filaments
forms round the equator of the cell, and
Cytokinesis then tightens to form a cleavage furrow ,
which splits the cell in two.

In plant cells vesicles move to the
equator, line up and fuse to form two
membranes called the cell…

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You don't need to know the details of meiosis at this stage (It's covered in module 5).
Meiosis and Sexual Reproduction
Sexual reproduction is the production of offspring from two parent using gametes . The
cells of the offspring have two sets of chromosomes (one from each parent), so are…

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During most of the life of a cell the chromatin is dispersed throughout the nucleus and
cannot be seen with a light microscope. At various times parts of the chromatin will unwind
so that genes on the DNA can be transcribed. This allows the proteins that the cell needs

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This display is called a karyotype, and it shows several features:
Different species have different number of chromosomes, but all members of the
same species have the same number. Humans have 46, chickens have 78,
goldfish have 94, fruit flies have 8, potatoes have 48, and so on. The number…


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