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Published byΚόρη Μπουκουβαλαίοι Modified over 6 years ago
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Meiosis! Meiosis Gametogenesis Genetic Recombination Errors in Meiosis
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Meiosis somatic cells (body cells) are diploid (2n)
they contain two copies of each chromosome human somatic cells contain 46 chromosomes
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Meiosis meiosis is a special type of cell division that only occurs in the reproductive organs meiosis results in the production of reproductive cells called gametes (sperm and eggs)
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Meiosis gametes are haploid (n)
they contain only one copy of each chromosome human gametes contain 23 chromosomes
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Meiosis each human sperm or egg cell contains:
1 sex chromosome that determines the sex of the individual 22 autosomal chromosomes (autosomes) that determine everything else
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Meiosis meiosis, involves the following phases: prophase I
metaphase I anaphase I telophase I 5) prophase II 6) metaphase II 7) anaphase II 8) telophase II
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Mitosis Meiosis I Meiosis II
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To do now…. Meiosis Crash Course Meiosis Microviewers Mieosis Cards
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Lesson Outline √ Meiosis Gametogenesis Genetic Recombination
Errors in Meiosis
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Gametogenesis the production of gametes Spermatogenesis
occurs in male testis results in four non-identical sperm cells
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Gametogenesis the production of gametes Oogenesis
occurs in female ovaries results in the production of one viable egg and three non-viable eggs (polar bodies)
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Gametogenesis the production of gametes Oogenesis
polar bodies result from unequal division of cytoplasm (there is only enough cytoplasm to support one viable egg)
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Lesson Outline √ √ Meiosis Gametogenesis Genetic Recombination
Errors in Meiosis √
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Genetic Recombination
a rearrangement of genetic material during meiosis contributes to variation among generations (the variation can be a success or failure in the environment)
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Genetic Recombination
two examples of genetic recombination are: crossing over independent assortment
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Genetic Recombination
Crossing Over occurs during prophase I occurs between non-sister chromosomes in a tetrad genetic information is exchanged between chromosomes of paternal and maternal origin
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Genetic Recombination
Crossing Over usually occurs between 2 – 3 times per chromosome (depending on length)
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Genetic Recombination
Independent Assortment occurs during prophase I when chromosomes begin to line up, the chromosomes of maternal and paternal origin do not necessarily line up on the same side
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Genetic Recombination
Independent Assortment this separates the maternal and paternal chromosomes into different gametes
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Lesson Outline √ √ √ Meiosis Gametogenesis Genetic Recombination
Errors in Meiosis √ √
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Errors in Meiosis errors in meiosis occur when the chromosomes fail to separate properly this is known as non-disjunction and results in gametes with more or less than the haploid number of chromosomes a
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Errors in Meiosis Trisomy one extra chromosome
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a a
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Errors in Meiosis Polyploidy
organisms with more than two complete sets of chromosomes (i.e. triploidy = 3n) common in plants and produces sterile offspring
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Lesson Outline √ √ √ √ Meiosis Gametogenesis Genetic Recombination
Errors in Meiosis Text Practice: reads page – highlight any vocab that is new – Compare: mitosis and meiosis √ √ √
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