Cell Division

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Interphase

The cell prepares to divide.

The DNA is unravelled abd replicated to double its genetic content

The organelles are replicated so it has space ones and ATP content is increased

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Prophase

Chromosomes condense getting shorter and fatter

Tiny bundles of protein (centrioles) start moving to opposite ends of the cell forming a network of protein fibres called the spindle

The nuclear envelope vreajs down and chromosomes lie free in the cytoplasm

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Metaphase

The chromosomes line up along the middle of the cell and become attached to the spindle by the centromere.

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Anaphase

The centromeres divide seperating each pair of sister chromatids

The spindles contract pulling chromatids to oppsite ends of the cell, centromere first

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Telophase

The chromatids reach opposite poles on the spinde

They uncoil and becme long and thin again- chromosomes

A nucleaur envelope forms around each group of chromosomes so there are now 2 daughter cells that are genetically identical to the original cells and to eachother.

Mitosis is finished and each daughter cell starts the interphase process again

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Observing mitois

You can stain chromosomes so that you can see them undder a microscope 

The means that you can watch them whilst they undergo mitosis

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Budding

Yeast cells reproduce asexually by budding

They are single celled organism and eukaryotic

Their offspring are genetically identical to the parent cell

1) A bud forms at the surface of the cell

2) The cell undergoes unterphae0 the DNA and organelles are replicated ready for the cell to divide

3) The cell begins to undergo mitosis

4) Nuclear division is complete- the budding cell contains a nucealus that has an identical copy of the parent cells DNA

5) FInally the bud seperates off from the parent cell producing a new, genetically ideantical yeast cell.

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Meiosis

Meiosis produces generically different cells 

1) The DNA replicates abd coils up into chromosomes

2) The chromosomes arrange themselves into homologous pairs

3) The chromosome pairs then swap bits with each other

4) In the first division, these homologous pairs split up. Any one chromosome from each pair can go into either cell as long as each cell gets one number 1 and one number 2

5) In the second division each chromosome splits in half. Ant half can go into any cell

6) Four new genetically different cells are produced

7) They're genetically different from eacohther because the chromosomes swap bit during meiosis and each gamete gets a combination of half of them at random

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