Chromosomes carry genes.
Thomas Hunt Morgan describes his discoveries using fruit flies.
Hi, I'm Thomas Hunt Morgan. In 1904, I started the "Fly" lab at Columbia University to study genetic variations. Many of the important discoveries of genetics and chromosomal inheritance came out of my lab through research using fruit flies. It all started when we found our first useful fruit fly mutation. Flies normally have red eyes but in January, 1910, we found a male with white eyes. We immediately crossed this male with a "wild type" female with red eyes. All the offspring of the first generation were red-eyed! We next crossed males and females from the first generation to each other. The white-eye trait reappeared in the expected 3:1 Mendelian ratio for a recessive trait. However, only the males had white eyes. This suggested that the white-eye trait is carried on the X chromosome. A Punnett square predicts the same results. I used a small "w" for the recessive white and a large "R" for the dominant red. Drosophila mutants are named according to the phenotype of the mutations. Crossing white-eyed males and red-eyed females from the second generation produced equal numbers of offspring with each eye color. Males have white eyes when they inherit the mutant gene on the X chromosome from their mother. Females only show the trait if they inherit mutant genes on both X chromosomes. I called this phenomenon "sex-limited" inheritance, but it became known as "sex-linked" or "X-linked." Within several years, we found more than 80 different mutations in fruit flies. Here are some of the flies from our fly library. I'm a wild type "normal" fly. I have red eyes, a brown body and regular size wings. I'm the famous white eye mutant. I'm a mutant for body color. I have a yellow body. I'm a mutant for wing size. I have miniature wings. I'm a double mutant. I have white eyes and a yellow body. I'm a double mutant. I have white eyes and miniature wings. I'm a double mutant. I have a yellow body and miniature wings. I'm a triple mutant.I have white eyes, a yellow body and miniature wings. Let's bring them all back so that we can compare. I became convinced that these little animals could show us the physical basis of heredity. So began my conversion from an experimental evolutionist to a geneticist.
thomas hunt morgan, geneticist, drosophila mutants, mutant genes, fly lab, fruit flies, genetic variations,chromosomal inheritance, punnett square, recessive trait, red eyes,white eyes, columbia university, wild type, x-chromosome, phenotype, sex-linked, "x-linked"
- ID: 16263
- Source: DNALC.DNAFTB
Fruit flies help to reveal that chromosomes carry genes.
DNAFTB Problem 11: Determine gene linkage in fruit flies.
DNAFTB Animation 11: Alfred Sturtevant describes gene mapping.
Calvin Bridges was a student of Thomas Hunt Morgan. Bridges advanced the theory of chromosomal non-disjunction, and did a lot of work on chromosomal banding patterns.
Thomas Hunt Morgan was one of the first true geneticists.
Herman Muller induces fruit fly mutations. Seymour Benzer works with virus mutants ans proved only one nucleotide change can cause mutation.
The fruit fly is easy to maintain, has large numbers of offspring, and grows quickly. The fruit fly shares with humans a number of so-called “master,” or homeotic, genes.
New York high school students set out to find Thomas Hunt Morgan's "Fly Room" at Columbia University, where seminal genetics research took place in the early 20th century.
Alfred Sturtevant was a student of Thomas Hunt Morgan. Sturtevant provided proof of genetic linkage.
DNAFTB Problem 10: Perform some fruit fly crosses.