115px|Metabolic network
Metabolism is the set of chemical reactions that happen in living
organisms to maintain life. These processes allow organisms to grow and
reproduce, maintain their structures, and respond to their
environments. The chemical reactions of metabolism are organized into
metabolic pathways, in which one chemical is transformed through a
series of steps into another chemical, by a sequence of enzymes.
Enzymes are crucial to metabolism because they allow organisms to drive
desirable reactions that require energy and will not occur by
themselves, by coupling them to spontaneous reactions that release
energy. As enzymes act as catalysts they allow these reactions to
proceed quickly and efficiently. Enzymes also allow the regulation of
metabolic pathways in response to changes in the cell's environment or
signals from other cells. The metabolism of an organism determines
which substances it will find nutritious and which it will find
poisonous. The speed of metabolism, the metabolic rate, also influences
how much food an organism will require. (more...)
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<http://en.wikipedia.org/wiki/Metabolism>
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Today's selected anniversaries:
1781:
American Revolutionary War: French naval forces handed Britain an major
strategic defeat in the Battle of the Chesapeake.
<http://en.wikipedia.org/wiki/Battle_of_the_Chesapeake>
1943:
World War II: American and Australian forces made an airborne landing
at Nadzab as part of the New Guinea campaign against Japan.
<http://en.wikipedia.org/wiki/landing_at_Nadzab>
1960:
Senegalese poet Léopold Sédar Senghor was elected as the first
President of Senegal.
<http://en.wikipedia.org/wiki/L%C3%A9opold_S%C3%A9dar_Senghor>
1972:
The Palestinian militant group Black September took hostage eleven
Israeli athletes and coaches at the Olympic Games in Munich, West
Germany; all of the hostages were killed less than 24 hours later.
<http://en.wikipedia.org/wiki/Munich_massacre>
1977:
NASA launched the robotic space probe Voyager 1, currently the man-made
object most distant from Earth.
<http://en.wikipedia.org/wiki/Voyager_1>
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Wiktionary's word of the day:
thermoception (n):
The sense of heat and cold
<http://en.wiktionary.org/wiki/thermoception>
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Wikiquote quote of the day:
Crazy Horse dreamed and went into the world where there is nothing but
the spirits of all things. That is the real world that is behind this
one, and everything we see here is something like a shadow from that
one.
--Black Elk
<http://en.wikiquote.org/wiki/Black_Elk>