Genetics Chapter: Morgan's Research and Discoveries

Thomas Hunt Morgan's Research

• Morgan was skeptical of previous research, focusing on controlled experiments to understand heredity
• He used fruit flies (Drosophila-fruit flies) for his experiments
• Fruit flies were ideal because of their wide range of traits, small number of chromosomes, and rapid reproduction
• In 1908, set up a lab at Columbia University, known as the "Fly Room"
• Bred millions of fruit flies, crossbreeding them to study variations in offspring using microscopy
• Key discovery: white-eyed trait linked to sex
• White-eyed trait appeared only in males
• Other sex-linked traits inherited together on the sex chromosome
• Sex determination chromosomes are X and Y (Males) and X (Females)
• Deduced that white eyes and other sex-linked traits are carried on the X chromosome
• Confirmed chromosomal theory of inheritance
• Extended Mendel's work in plants to animals, a pivotal moment in genetics
• His experiments enabled him to trace inherited physical characteristics and determine the exact behavior of genes.
• The second generation of cross-bred flies revealed the white-eyed trait passed through the male line.

Genetic Mutations Research

• Hermann Muller, an American geneticist, received a Nobel Prize for his work on genetic mutations
• Found that hereditary changes could be induced artificially by X-rays
• Inspired by Morgan's work on fruit flies
• Conducted experiments at Columbia University to study genetic mutations induced by X-rays
• Became a pioneer in raising awareness of radiation's long-term dangers and campaigned for controls on nuclear weapons
• His work was significant in showcasing how mutations could be created artificially