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The Chromosomal Basis of Inheritance

The Chromosomal Basis of Inheritance. Marie Černá. Thomas Hunt Morgan 1910 s - 20s. Morgan’s experiments. fruit fly: Drosophila melanogaster prolific breeders (100s of offspring / 2 weeks) 4 pairs of chromosomes (8, XY; 8, XX). Morgan’s laws. linked genes on the same chromosome

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The Chromosomal Basis of Inheritance

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  1. The Chromosomal Basis of Inheritance Marie Černá

  2. Thomas Hunt Morgan1910s- 20s

  3. Morgan’s experiments fruit fly: Drosophila melanogaster • prolific breeders (100s of offspring / 2 weeks) • 4 pairs of chromosomes (8, XY; 8, XX)

  4. Morgan’s laws linked genes on the same chromosome • are located linearly in the gene loci • tend to be inherited together

  5. Genetic recombination • Independent assortment of chromosomes (unlinked genes) - 50% frequency • crossing over (linked genes) - the greater the distance between two genes, the more points there are between them where crossing over can occur 1 centimorgan = 1% recombination frequency

  6. Genetic maps • linkage map - based on recombination frequencies • cytological map - based on stained bands of chromosomes that can be seen in the microscope • genetic map - based on DNA nucleotide sequences

  7. Sex determination • in mammals(humans), some insects (fruit flies) • in some insects (grasshoppers, crickets, roaches) • in birds, some fishes, some insects (butterflies, moths) • in bees and ants

  8. Literature Biology, eighth edition, Campbell, Reece Unit three: Genetics Chapter 15: The Chromosomal Basis of Inheritance Pages 286 - 296

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