Meiosis

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What is meiosis?
A process to which the nucleus divides twice forming 4 haloid cells from 1 diploid cell
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What is a diploid cell?
A cell with the normal chromosome number (2 chromosomes of each type, inherited from each parent)
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What is a haploid cell?
A cell with half the normal chromosome number of the parent cell (one chromosome of each type)
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Why is meiosis known as reduction division?
Because it reduces the number of chromosomes in each cell
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What is a homologous chromosome?
A matching pair of chromosomes, one from each parent
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What is an allele?
Different versions of the same gene ( Eg. blue eyes allele and brown eyes allele), deiffernt alleles of a gene will have the same position (locus) on a chromosome.
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What is meiosis 1?
The first division of meiosis, homologous chromosomes separate into 2 cells, each cell has 1 full set of genes instead of 2 (haploid)
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What is meiosis 2?
The second division, similar to mitosis, pairs of chromatids are separated forming 2 more cells (therefore producing an overall of 4 haploid cells)
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Prophase 1
(same process as in mitosis) THEN homologous chromosomes pair up forming bivalents, chromotids entangle (crossing over)
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Metaphase 1
(Same as in mitosis) BUT the pairs of chromosomes (maternal chromosome paired with paternal chromosome) instead of the individual chromosomes line up randomly (independent assortment), leading to genetic variation
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What is independent assortment?
When the homologous chromosomes randomly line up on the metaphase plate (equator) randomly so the maternal and paternal chromosomes can end up facing either pole
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Anaphase 1
Chromosomes are pulled to opposite poles (chromatids stay attached), chromatids that got entangled during crossing over, break off and rejoin. Genes are exchanged between chromatids forming recombinant chromatids
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How does anaphase 1 create genetic variation?
Becuase of the exchanged genes, there will be a different combination of alleles on the chromatids
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What is chaismata?
The points where the chromatids break and rejoin
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Telophase 1
The same as in metaphase
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Prophase 2
Same as mitosis (chromosomes condense and become visable, nuclear envelope breaks down, spindle formation begins)
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Metaphase 2
Same as mitosis, the chromatids are no longer identical so there is more independent assortment and more genetic variation
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Anaphase 2
Same as mitosis
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Telophase 2
Same as mitosis, cytokinesis results in 4 daughter haploid cells which are all genetically different
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Other cards in this set

Card 2

Front

What is a diploid cell?

Back

A cell with the normal chromosome number (2 chromosomes of each type, inherited from each parent)

Card 3

Front

What is a haploid cell?

Back

Preview of the front of card 3

Card 4

Front

Why is meiosis known as reduction division?

Back

Preview of the front of card 4

Card 5

Front

What is a homologous chromosome?

Back

Preview of the front of card 5
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