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The Chromosomal Basis of Inheritance

Explore Thomas Hunt Morgan's groundbreaking experiments in the 1910s-20s using fruit flies to uncover the key principles of genetic inheritance, such as linked genes, genetic recombination, and sex determination. Learn about chromosomal mapping and genetic laws in this fascinating journey through early genetics research.

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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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