Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount...
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![Page 1: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/1.jpg)
![Page 2: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/2.jpg)
Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount
Why would you want to reduce chromosomes to half? (check with
your neighbor)
![Page 3: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/3.jpg)
![Page 4: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/4.jpg)
Egg = 23
Sperm = 23
Egg + Sperm = 46 in them.
If meiosis reduces the chromosome number
in half, how many chromosomes are in
human sex cells?
![Page 5: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/5.jpg)
Haploid (n)– a half set of chromosomes
Diploid (2n) – a full set of chromosomes
Somatic Cells = ALL body cells (blood, skin, etc) except gametes
![Page 6: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/6.jpg)
Gamete
Skin Cell
Egg
Somatic Cell
Sperm
Sex Cell
Haploid or Diploid?
![Page 7: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/7.jpg)
Homologous Chromosomes – chromosomes that have the same
informationEx. Father/Paternal #11 chromosome
Mother/Maternal #11 chromosome
“Partner” up in Prophase 1
![Page 8: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/8.jpg)
Crossing Over is the exchange of genetic material between homologous chromosomes
Crossing Over acts as a source of
genetic variation within a species
![Page 9: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/9.jpg)
![Page 10: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/10.jpg)
Stages of Meiosis•Interphase—1 time ONLY
– Growth and replication of DNA
• PMATC—2 times
– Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
![Page 11: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/11.jpg)
Diploid Cell—2 copies of each chromosome that replicated during
Interphase
![Page 12: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/12.jpg)
Crossing Over occurred during Prophase 1
![Page 13: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/13.jpg)
Anaphase AWAY
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Telophase I/Cytokinesis results in 2 Haploid Cells
![Page 15: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/15.jpg)
Prophase II looks similar to Telophase I, but nuclear envelope is
disappearing again
![Page 16: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/16.jpg)
![Page 17: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/17.jpg)
Anaphase Away—part II
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Telophase II and Cytokineses results in 4 HAPLOID sex cells….or gametes….or egg….or
sperm!
![Page 19: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/19.jpg)
![Page 20: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/20.jpg)
![Page 21: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/21.jpg)
What’s different?
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Egg (Ovum) is created in the Ovary
![Page 23: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/23.jpg)
Sperm is created in the Testis
![Page 24: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/24.jpg)
Diploid Numbers in other OrganismsName of Organism Diploid Number Image
Adders-tongueOphioglossum reticulatum
1440This fern has the highest known chromosome number of any life form
Field HorsetailEquisetum arvense 216
Red viscacha ratTympanoctomys barrerae
102 Highest number known in mammals, a tetraploid[3].
Hedgehog
90
![Page 25: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/25.jpg)
Diploid Numbers in other OrganismsName of Organism Diploid Number Image
Turkey
80Dogs, Coyotes, Dingos, and Wolves 78
MuleHorse/Donkey Cross 63 *Infertile
Platypus 5210 Sex Chromosomes
Jack Jumper Ant 2 for females, 1 for males
![Page 26: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/26.jpg)
Karyotype – a “map” of chromosomes
2 Main Uses:•Determine sex of the baby
•Screen for Chromosomal Abnormalities
Ex. Down Syndrome
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22 pair of Autosomes + 1 pair of sex chromosomes =23 Total pairs
XX = Female
XY = Male
![Page 28: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/28.jpg)
![Page 29: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/29.jpg)
![Page 30: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/30.jpg)
Questions about Meiosis????
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Quiz
• What are sex chromosomes called?
• How many chromosomes does a diploid cell have? Haploid?
• What is a karyotype used for?
![Page 32: Meiosis is a process that reduces the amount of chromosomes in a cell to half the original amount Why would you want to reduce chromosomes to half? (check.](https://reader036.fdocuments.us/reader036/viewer/2022062516/56649e585503460f94b5110d/html5/thumbnails/32.jpg)
Quiz
• What is the purpose of crossing over?
• What does meiosis in male gametes create??
• What does meiosis female gametes create?