Barbara McClintock was a pioneering American scientist and one of the
world's most distinguished cytogeneticists. McClintock received her
PhD in botany from Cornell University in 1927, where she was a leader
in the development of maize cytogenetics; the field remained the focus
of her research for the rest of her career. Her work was
groundbreaking: she developed the technique to visualize maize
chromosomes and used microscopic analysis to demonstrate many
fundamental genetic concepts, including genetic recombination by
crossing-over during meiosis—a mechanism by which chromosomes
exchange information. She produced the first genetic map for maize,
linking regions of the chromosome with physical traits, and she
demonstrated the role of the telomere and centromere, regions of the
chromosome that are important in the conservation of genetic
information. During the 1940s and 1950s, McClintock discovered
transposition and using this system showed how genes are responsible
for turning on or off physical characteristics. Awards and recognition
of her contributions to the field followed, including the Nobel Prize
in Physiology or Medicine awarded to her in 1983 for the discovery of
genetic transposition; she was the first and only woman to receive an
unshared Nobel Prize in that category.
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Today's selected anniversaries:
Ferdinand Magellan and his crew reached Guam and were greeted by the
Texas Revolution: Mexican forces captured the Alamo after a 13-day
The U.S. Supreme Court ruled in the Dred Scott Case, a landmark
decision that led to several constitutional amendments.
Dmitri Mendeleev (pictured) presented the first Periodic Table of
Elements to the Russian Chemical Society.
British ferry M/S Herald of Free Enterprise capsized while leaving the
harbour of Zeebrugge, Belgium, killing 193 on board.
Wikiquote of the day:
"Give thought to life and liberty." -- Cyrano de Bergerac