Jumpin’ Genes
Year of Discovery: 1950
What Is It? Genes are not permanently fixed on chromosomes, but can jump
from position to position.
Who Discovered It? Barbara McClintock
Why Is This One of the 100 Greatest?
Every researcher in the world accepted that genes were strung along chromosomes in
fixed positions like pearls on a necklace. Working alone in a small, windswept cornfield at
Cold Springs Harbor, Long Island, Barbara McClintock proved every other genetic scientist in the world wrong.
Carefully studying wild corn, Barbara McClintock found that genes not only can
jump, but regularly do jump from one position to another on a chromosome. She found that
a few controlling genes direct these jumping messenger genes to shift position and turn on,
or turn off, the genes next to them in their new location.
Barbara McClintock’s work became the building block for a dozen major medical and
disease-fighting breakthroughs. The 1983 Nobel Prize Committee called Barbara
McClintock’s pioneering work “one of the two great discoveries of our time in genetics.”
How Was It Discovered?
With a Ph.D. in genetics, Barbara McClintock lived in a trim two-room apartment over the
bright-green-painted garage of the Carnegie Institute’s Cold Spring Harbor Research Facility.
A small, slight woman, Barbara stood barely five feet tall and weighed less than 90
pounds. Her face and hands were worn and wrinkled from long exposure to wind and sun.
Cold Spring Harbor is an isolated spot on northeastern Long Island characterized by
wind, rolling sand dunes, and waving shore grass. Stooping in a small half-acre cornfield
tucked between the facility’s cluster of buildings and the choppy waters of the Long Island
Sound, Barbara planted corn seeds by hand one-by-one in carefully laid out rows.
The year 1950 was Barbara’s sixth year of planting, growing, and studying the genes
of these corn plants as they passed from generation to generation. She often felt more like a
farmer than a genetics researcher.
How Barbara spent her days depended on the season. In summer, most of her time was
spent in the cornfield, nurturing the plants that would produce her data for the year, weeding, checking for pests and disease that could ruin her experiments. In the fall she harvested
each ear by hand, carefully labeled it, and began her lab analysis of each gene’s location and
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