BIOL 1543 Lecture Notes - Lecture 13: Spermatogenesis, Homologous Chromosome, Sister Chromatids
25 Aug 2016
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Document Summary
A karyotype is a photographic inventory of an individual"s chromosomes: a karyotype is an ordered display of magnified images of an individual"s chromosomes arranged in pairs, karyotypes. Are often produced from dividing cells arrested at metaphase of mitosis. Chromosome structure: karyotyping uses fluorescent stains and binds to different parts of chromosome showing parts of a chromosome. An extra copy of chromosome 21 causes down syndrome: trisomy 21. Involves the inheritance of three copies of chromosome 21. Most common human chromosome abnormality: trisomy 21, called down syndrome, produces a characteristic set of symptoms: Susceptibility to respiratory infections, leukemia, and alzheimer"s disease. Accidents during meiosis can alter chromosome number: nondisjunction failure of chromosomes or chromatids to separate normally during meiosis. Meiosis i if both members of a homologous pair go to one pole or. Meiosis ii both sister chromatids go to one pole: fertilization after nondisjunction yields zygotes with altered numbers of chromosomes.
