Function of Chromosomes
Year of Discovery: 1909
What Is It? Genes are grouped (linked) in groups that are strung along
chromosomes.
Who Discovered It? T. H. Morgan
Why Is This One of the 100 Greatest?
Morgan’s discovery that genes were linked into groups and strung along chromosomes
was the second major step in peeling back the mystery of heredity and evolution. Morgan’s
discovery formed much of the foundation for later discoveries of how genes and chromosomes do their work as well as the structure of the DNA molecule.
Mendel established that traits (called “genes”) are passed from parents into the next
generation. Darwin established the concepts that dictated evolution of species. Still, science
had no idea how species evolved or how individual genes were passed to new generations.
Studying a species of fruit flies, Professor T. H. Morgan at Columbia University both
proved that Mendel’s theory was correct and established the existence of chromosomes as
the carriers for genes.
How Was It Discovered?
By 1910, 44-year-old professor T. H. Morgan was the head of the biology department
at New York’s Columbia University. All his energy, however, he saved for his research.
Morgan refused to accept Mendel’s theories on heredity. Morgan didn’t believe in the existence of genes since no one had physically seen a gene.
Neither did he accept Darwin’s concept of survival of the fittest as the driving force of
evolution. Morgan believed that evolution came from random mutations that slowly
worked their way into and through a population. Morgan created “The Fly Room” to prove
his ideas.
Morgan’s Fly Room laboratory was a small, messy room with the overpowering reek
of rotting bananas. Two walls were lined floor to ceiling with rows of corked glass bottles
containing tens of thousands of tiny fruit flies. Their constant buzz was difficult to talk over.
He chose to study fruit flies for four reasons. First, they were small (only ¼-inch long).
Second, they lived their entire lives on nothing but mashed banana. Third, they created a
new generation in less than two weeks. Morgan could study almost 30 generations a year.
Finally, they had few genes and so were much easier to study than more complex species.
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