This is when cells start with the full number of chromosomes to start with. But this halfs in meiosis, creating haploid cells.
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What is the first step in meiosis?
Prophase 1
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What happens in Prophase 1?
The chromosomes condense. They pair themselves into homologous pairs. Crossing over occurs. Centrioles start moving to opposite ends of the cell. Spindle fibres formed. The nuclear envelope breaks down.
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What is crossing over?
Where homologous pairs twist around one another and swap chromatids. Therefore the chromatides have the same genes but with a different combination of alleles.
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What is the second stage of meiosis?
Metaphase 1
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What happenes in Metaphase 1?
The homologous pairs line up acros the center of of the cell and attach to to the spindle fibres by their centromere.
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What is the third stage of meiosis?
Anaphase 1
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What happens in Anaphase 1?
The spindles contract, separating the homologous pairs. One chromosome goes to each end of the cell. due to this seperation independent assortment happens.
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What is independent assortment?
Due to each homologous pair being made up of 1 chromosome from mum and 1 from dad, it is completly random which chromosome from which pair will end up in each daughter cell. So each of the four daughter cells have different combinations of chromosome
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What is the fourth stage in meiosis?
Telophase 1
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What happens in Telophase 1?
A nuclear envelope forms arond each group of chromosomes.
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What happens after Telophase 1 ?
Cytokinesis creating two hapliod cells to be produced.
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What is the fifth, sixth, seventh and eighth stages of meiosis?
Prophase 2, metaphase 2, anaphase 2 and telophase 2 (followed by cytokinesis).
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What is the only difference in the second division in meiosis to mitosis?
In anaphase 2 the pair of sister chromatids are seperated so that each daughter cell gets 1 chromatid from each chromosome. 4 hapliod daughter cells are prduced -> gametes.
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Other cards in this set
Card 2
Front
What is reduction division?
Back
This is when cells start with the full number of chromosomes to start with. But this halfs in meiosis, creating haploid cells.
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