meiosis presentation for pfs 2014
DESCRIPTION
Life sciences education on Meiosis done by a third year education student majoring in life scienceTRANSCRIPT
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Meiosis
JL Broadhurst201242029
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What is meiosis?
Cell division for sex-cells.Sex Cells:
Are also called Gametes.
You know them as SPERM and EGG cells
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What happens?
2 divisions: Meiosis I and Meiosis II
Starting with ONE (diploid) cell, ending with FOUR (haploid) cells.
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Meiosis I
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Meiosis II
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Interphase: Chromosomes duplicate and build up energy for meiosis
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Stages of Meiosis
Meiosis IProphase I
Metaphase IAnaphase ITelophase I
Meiosis IIProphase II
Metaphase IIAnaphase IITelophase II
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Meiosis IProphase I
Prophase I- chromosome becomes visible and the nuclear membrane disappears; homologous chromosome appears and share fragments called crossing over
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What does “crossing over” cause????
More genetic DIVERSITY!!
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Meiosis IMetaphase I
- complete disappearance of nuclear membrane and appearance of spindle fiber; centromeres attached to the spindle fiber and lies on the metaphase plate.
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Meiosis IAnaphase I
homologous chromosome separates from each other but centromere do not divide; chromosome continues to consists of two chromatids
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Meiosis ITelophase I
chromosomes are still doubled; nuclear membrane is formed and disappearance of spindle fiber
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Meiosis II Prophase II
cells have one chromosome
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Meiosis IIMetaphase II
chromosomes align at the metaphase plate; centromeres divide thus separating the chromatids
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Meiosis IIAnaphase II
each new daughter cell move towards opposite poles
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Meiosis IITelophase II
spindle disappears; nuclear membrane is formed; nuclei are formed and cytokinesis happens
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Comparing Mitosis and Meiosis Mitosis makes
cells for growth, development, repair, and is a form of asexual reproduction
Meiosis makes gametes for sexual reproduction
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Comparing Mitosis and Meiosis
Mitosis produces two cells identical to the parent cell (diploid - called daughter cells)
Meiosis produces four cells with half the number of chromosomes as the parent (haploid)
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Comparing Mitosis and Meiosis
In the first cell division, CHROMOSOME PAIRS (HOMOLOGOUS CHROMOSOMES) are separated.
In the second cell division, SISTER CHROMATIDS are pulled apart.
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Comparing Mitosis and Meiosis In meiosis, “crossing
over” occurs during prophase I.
Chromosomes form tetrads
Homologous chromosomes “swap” parts of their DNA leads to recombination, or genetic variation
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Reference list: http://www.slideshare.net/imkaelah/meiosis-lesson?qid=bf07a3ac-c563-4350-af21-
a255071068Meiosis lessonby imkaelah on Jul 24, 2013 http://
www.slideshare.net/mmravagnan/powerpoint-meiosis?qid=bf07a3ac-c563-4350-af21-a255071068ef&v=qf1&b=&from_search=18
Powerpoint meiosisby Magdalena Ravagnan, Veterinaria, Biology teacher from Argentina on Jun
16,2013 http://www.slideshare.net/MRKALEMBER/meiosis-in-depth?qid=bf07a3ac-c563-4
350-af21-a255071068ef&v=qf1&b=&from_search=3
Meiosis in depthby Jeff Kalember on Jan 30, 2014 http://www.slideshare.net/mjurkiewicz/meiosis-29211193?qid=bf07a3ac-c563-43
50-af21-a255071068ef&v=qf1&b=&from_search=9
Meiosisby mjurkiewicz on Dec 14, 2013 http://www.slideshare.net/rozeka01/biology-unit-4-cell-division-meiosis-notes?qi
d=bf07a3ac-c563-4350-af21-a255071068ef&v=qf1&b=&from_search=10
Biology unit 4 cell division meiosis notesby rozeka01 on Dec 12, 2013