Enzymes are proteins that accelerate, or catalyze, chemical
reactions.
In these reactions, molecules called substrates are converted by
enzymes into different molecules called products. Almost all
processes
in the cell need enzymes in order to occur at significant rates.
Like
all catalysts, enzymes work by providing an alternative path of lower
activation energy for a reaction and dramatically increasing its
rate;
some enzymes can make the conversion of substrate to product occur
many millions of times faster. Enzymes are not consumed in chemical
reactions, nor do they alter the equilibrium of a reaction. However,
enzymes do differ from most other catalysts by being much more
specific. Since enzymes are extremely selective for their substrates
and speed up only a few reactions, the set of enzymes made in a cell
determines which metabolic pathways occur in that cell. Many drugs
and
poisons work by inhibiting enzyme activity.
Read the rest of this article:
http://en.wikipedia.org/wiki/Enzyme
_______________________________
Today's selected anniversaries:
1850:
The University of Sydney, Australia's oldest university, was
established in Sydney.
(http://en.wikipedia.org/wiki/University_of_Sydney)
1865:
The Morant Bay rebellion, led by Paul Bogle and George William Gordon,
began in Jamaica and was brutally suppressed by Governor Edward John
Eyre.
(http://en.wikipedia.org/wiki/Morant_Bay_rebellion)
1899:
The Second Boer War erupted in South Africa between the United Kingdom
and the Boers.
(http://en.wikipedia.org/wiki/Second_Boer_War)
1954:
Ho Chi Minh and the Viet Minh took control of North Vietnam.
(http://en.wikipedia.org/wiki/Viet_Minh)
1968:
NASA launched Apollo 7, the first manned mission of the Apollo
program.
(http://en.wikipedia.org/wiki/Apollo_7)
_____________________
Wikiquote of the day:
It takes courage to love, but pain through love is the purifying fire
which those who love generously know. We all know people who are so
much afraid of pain that they shut themselves up like clams in a
shell
and, giving out nothing, receive nothing and therefore shrink until
life is a mere living death. -- Eleanor Roosevelt
(http://en.wikiquote.org/wiki/Eleanor_Roosevelt)
Raising the Flag on Iwo Jima is an iconic photograph taken on
February
23, 1945 by Joe Rosenthal. It depicts five United States Marines and
a
U.S. Navy corpsman raising the Flag of the United States atop Mount
Suribachi during the Battle of Iwo Jima in World War II. The
photograph was instantly popular, being reprinted in hundreds of
publications. Later, it became the only photograph to win the
Pulitzer
Prize for Photography in the same year as its publication, and
ultimately came to be regarded as one of the most significant and
recognizable images in history, and possibly the most reproduced
photograph of all time. Of the six men depicted in the picture,
three
(Franklin Sousley, Harlon Block, and Michael Strank) did not survive
the battle; the three survivors (John Bradley, Rene Gagnon, and Ira
Hayes) became suddenly famous. The photograph was later used by
Felix
de Weldon to sculpt the USMC War Memorial, located just outside
Washington, D.C.
Read the rest of this article:
http://en.wikipedia.org/wiki/Raising_the_Flag_on_Iwo_Jima
_______________________________
Today's selected anniversaries:
1514:
Mary Tudor, sister of Henry VIII of England, became queen consort of
France.
(http://en.wikipedia.org/wiki/Mary_Tudor_%28queen_consort_of_France%29)
1831:
John Capodistria, the Greek head of state, was assassinated in
Náfplio.
(http://en.wikipedia.org/wiki/John_Capodistria)
1888:
The Washington Monument, then the world's tallest building, officially
opened to the general public.
(http://en.wikipedia.org/wiki/Washington_Monument)
1919:
The Black Sox scandal: The Cincinnati Reds "defeated" "Shoeless Joe"
Jackson and the Chicago White Sox to "win" the World Series major
league baseball championship by 5 games to 3.
(http://en.wikipedia.org/wiki/1919_World_Series)
1962:
Uganda became independent from the United Kingdom, with Milton Obote
as the first Prime Minister.
(http://en.wikipedia.org/wiki/Uganda)
_____________________
Wikiquote of the day:
Imagine all the people
Sharing all the world...
You may say I'm a dreamer
But I'm not the only one
I hope someday you'll join us
And the world will live as one. -- John Lennon
(http://en.wikiquote.org/wiki/John_Lennon)
Adi Shankara (c. 788 – 820 AD) was the first philosopher to
consolidate the doctrine of Advaita Vedanta, a sub-school of
Vedanta.
His teachings are based on the unity of the soul and God, in which
God
is viewed as simultaneously personal and attributeless. In the
Smārta
tradition, Adi Shankara is regarded as an incarnation of Shiva. Adi
Shankara toured India with the purpose of propagating his teachings
through discourses and debates with other philosophers. He founded
four mathas which played a key role in the historical development and
spread of Hinduism and Advaita Vedanta. Adi Shankara was the founder
of the Dashanami monastic order and the Shanmata tradition of
worship.
His works in Sanskrit, all of which are extant today, concern
themselves with establishing the doctrine of Advaita (Sanskrit,
"Non-dualism"). Adi Shankara quotes extensively from the Upanishads
and other Hindu scriptures in forming his teachings. He also
includes
polemics against opposing schools of thought like Samkhya and
Buddhism
in his works.
Read the rest of this article:
http://en.wikipedia.org/wiki/Adi_Shankara
_______________________________
Today's selected anniversaries:
3761 BCE:
The epoch of the modern Hebrew calendar.
(http://en.wikipedia.org/wiki/Hebrew_calendar)
1571:
The Ottoman Empire was decisively defeated by the Christian West for
the first time, as a multinational fleet led by Don John of Austria
crushed the Turkish navy near the Gulf of Corinth in the Battle of
Lepanto.
(http://en.wikipedia.org/wiki/Battle_of_Lepanto_(1571))
1949:
The German Democratic Republic was proclaimed in East Berlin.
(http://en.wikipedia.org/wiki/German_Democratic_Republic)
1985:
The Mediterranean ocean liner Achille Lauro was hijacked by Palestine
Liberation Front terrorists while sailing from Alexandria to Port
Said.
(http://en.wikipedia.org/wiki/Achille_Lauro)
2003:
California recall: Californians voted to recall Governor Gray Davis
from office and elected Arnold Schwarzenegger from a list of 135
candidates.
(http://en.wikipedia.org/wiki/California_recall_election%2C_2003)
_____________________
Wikiquote of the day:
It is wrong to think that the task of physics is to find out how
nature is. Physics concerns what we can say about nature. -- Niels
Bohr
(http://en.wikiquote.org/wiki/Niels_Bohr)
Gas tungsten arc welding is an arc welding process that uses a
nonconsumable tungsten electrode to produce the weld. The weld area
is
protected from atmospheric contamination by a shielding gas (usually
an inert gas such as argon), and a filler metal is normally used,
though some welds, known as autogenous welds, do not require it. A
constant-current welding power supply produces energy which is
conducted across the arc through a column of highly ionized gas and
metal vapors known as a plasma. GTAW is most commonly used to weld
thin sections of stainless steel and light metals such as aluminum,
magnesium, and copper alloys. The process grants the operator
greater
control over the weld than competing procedures such as shielded
metal
arc welding and gas metal arc welding, allowing for stronger, higher
quality welds. However, GTAW is comparatively more complex and
difficult to master, and furthermore, it is significantly slower than
most other welding techniques. A related process, plasma arc
welding,
uses a slightly different welding torch to create a more focused
welding arc and as a result is often automated.
Read the rest of this article:
http://en.wikipedia.org/wiki/Gas_tungsten_arc_welding
_______________________________
Today's selected anniversaries:
105 BC:
The Cimbri and the Teutons inflicted a major defeat on the Roman
Republic in the Battle of Arausio.
(http://en.wikipedia.org/wiki/Battle_of_Arausio)
1927:
The first successful talking movie The Jazz Singer, starring Al
Jolson, was released.
(http://en.wikipedia.org/wiki/The_Jazz_Singer_(1927_film))
1976:
Premier Hua Guofeng ordered the arrest of the Gang of Four and their
associates, putting an end to the Cultural Revolution in China.
(http://en.wikipedia.org/wiki/Gang_of_Four_(China))
1981:
Egyptian President Mohamed Anwar el-Sadat was assassinated while
attending a parade in Cairo to mark the eighth anniversary of the
Crossing of the Bar Lev Line at the start of the 1973 Arab-Israeli
War.
(http://en.wikipedia.org/wiki/Anwar_Sadat)
1995:
An article in the journal Nature reported the discovery of a planet
orbiting 51 Pegasi as the first known extrasolar planet around a
main-sequence star.
(http://en.wikipedia.org/wiki/51_Pegasi)
_____________________
Wikiquote of the day:
Behold, we know not anything; I can but trust that good shall fall At
last — far off — at last, to all, And every winter change to spring.
So runs my dream; but what am I? An infant crying in the night; An
infant crying for the light, And with no language but a cry. --
Alfred, Lord Tennyson
(http://en.wikiquote.org/wiki/Alfred_Tennyson)
The Lord of the Rings is an epic high fantasy novel written by J.
R.
R. Tolkien. The story began as a sequel to Tolkien's earlier
fantasy
book The Hobbit and soon developed into a much larger story. It was
written in stages between 1937 and 1949, with much of it being
written
during World War II. It was originally published in three volumes in
1954 and 1955, and has since been reprinted numerous times and
translated into at least 38 different languages, becoming one of the
most popular works in twentieth-century literature. The action in
The
Lord of the Rings is set in what the author conceived to be the lands
of the real Earth, inhabited by humanity but placed in a fictional
past before our history. Tolkien gave this setting a modern English
name, Middle-earth, a rendering of the Old English Middangeard. The
story concerns peoples such as Hobbits, Elves, Men, Dwarves, Wizards,
and Orcs, and centres on the Ring of Power made by the Dark Lord
Sauron. Starting from quiet beginnings in The Shire, the story
ranges
across Middle-earth and follows the courses of the War of the Ring.
Read the rest of this article:
http://en.wikipedia.org/wiki/The_Lord_of_the_Rings
_______________________________
Today's selected anniversaries:
1877:
After battling U.S. armed forces for more than three months,
retreating
over 1,000 miles across Oregon, Washington, Idaho, and Montana, and
enduring a five-day siege, Chief Joseph and his Nez Percé band finally
surrendered.
(http://en.wikipedia.org/wiki/Chief_Joseph)
1908:
Prince Ferdinand became the first Tsar of Bulgaria since the Ottoman
invasion in the 14th century.
(http://en.wikipedia.org/wiki/Ferdinand_I_of_Bulgaria)
1930:
The British airship R101 crashed in France en route to India on its
maiden voyage, killing 48 passengers and crew.
(http://en.wikipedia.org/wiki/R101)
1969:
The first episode of Monty Python's Flying Circus was broadcast on
BBC1.
(http://en.wikipedia.org/wiki/Monty_Python's_Flying_Circus)
1970:
Members of the Front de Libération du Québec kidnapped a British
diplomat,
sparking the October Crisis in Montréal, Canada.
(http://en.wikipedia.org/wiki/Front_de_libération_du_Québec)
_____________________
Wikiquote of the day:
Almost all men, and those that seem to be very miserable, love life,
because they cannot bear to lose sight of such a beautiful and lovely
world. The ideas, that every moment whilst we live have a beauty
that
we take not distinct notice of, brings a pleasure that, when we come
to the trial, we had rather live in much pain and misery than lose.
-- Jonathan Edwards
The ideas, that every moment whilst we live have a
beauty... that, when we come to the trial, we had rather live in much
pain and misery than lose. -- Jonathan Edwards
(http://en.wikiquote.org/wiki/Jonathan_Edwards)
Dürer's Rhinoceros is the name commonly given to a woodcut engraved
by
Albrecht Dürer in 1515. The image was based on a written description
and brief sketch by an unknown artist of an Indian rhinoceros that
had
arrived in Lisbon earlier that year. Dürer never saw the actual
rhinoceros, which was the first living example seen in Europe since
Roman times. In late 1515, the King of Portugal, Manuel I, sent the
animal as a gift for Pope Leo X, but it died in a shipwreck off the
coast of Italy in early 1516. A live rhinoceros was not seen again
in
Europe until a second specimen arrived from India at the court of
Phillip II in Spain in 1577. Despite its anatomical inaccuracies,
Dürer's woodcut became very popular in Europe and was copied many
times in the following three centuries. It was regarded as a true
representation of a rhinoceros into the late 18th century.
Eventually,
it was supplanted by more realistic drawings and paintings,
particularly paintings and engravings of Clara the rhinoceros, who
toured Europe in the 1740s and 1750s. It has been said of Dürer's
woodcut that "probably no animal picture has exerted such a profound
influence on the arts".
Read the rest of this article:
http://en.wikipedia.org/wiki/D%C3%BCrer%27s_Rhinoceros
_______________________________
Today's selected anniversaries:
1830:
Belgian Revolution: A provisional government in Brussels declared the
creation of the independent and neutral state of Belgium, in revolt
against the United Kingdom of the Netherlands.
(http://en.wikipedia.org/wiki/Belgian_Revolution)
1883:
The Orient Express began operations.
(http://en.wikipedia.org/wiki/Orient_Express)
1910:
Manuel II, the last King of Portugal, fled to the United Kingdom when
a revolution erupted in Lisbon and his palace was shelled. The
Portuguese First Republic was proclaimed the next day.
(http://en.wikipedia.org/wiki/Manuel_II_of_Portugal)
1957:
Soviet spacecraft Sputnik 1 was launched by an R-7 rocket from
Baikonur Cosmodrome, Kazakh SSR and became the first artificial
satellite to orbit the Earth.
(http://en.wikipedia.org/wiki/Sputnik_1)
1993:
Russian Constitutional Crisis: Tanks bombarded the White House in
Moscow, a government building that housed the Russian parliament,
where demonstrators against President Boris Yeltsin rallied outside.
(http://en.wikipedia.org/wiki/Russian_constitutional_crisis_of_1993)
_____________________
Wikiquote of the day:
A comedian does funny things. A good comedian does things funny. --
Buster Keaton
(http://en.wikiquote.org/wiki/Buster_Keaton)
Detroit is the largest city in the U.S. state of Michigan and the
seat
of Wayne County. Founded in 1701 by French fur traders, it is a
major
port city north of Windsor, Ontario located on the Detroit River in
the Midwestern region of the United States. In 2005, Detroit ranked
as
the United States's 11th most populous city with 886,675 residents;
this is less than half of the peak population it had in 1950, and
Detroit leads the nation in terms of declining urban population. It
is
the focus city of the nation's tenth-largest metropolitan area, and
the fourth-largest if Windsor and its environs are included.
Detroit's
crime rate has brought it notoriety while the city continues to
struggle with the burdens of racial disharmony between itself and its
suburban neighbors.
Read the rest of this article:
http://en.wikipedia.org/wiki/Detroit%2C_Michigan
_______________________________
Today's selected anniversaries:
1187:
The Siege of Jerusalem: Ayyubid forces led by Saladin captured
Jerusalem, prompting the Third Crusade.
(http://en.wikipedia.org/wiki/Siege_of_Jerusalem_(1187))
1535:
French explorer Jacques Cartier sailed along the St. Lawrence River
and reached an Iroquois fort on the island now known as Montréal.
(http://en.wikipedia.org/wiki/History_of_Montreal)
1835:
Mexican dragoons dispatched to disarm settlers at Gonzales, Texas
encountered stiff resistance from a Texian militia in the Battle of
Gonzales, the first armed engagement of the Texas Revolution.
(http://en.wikipedia.org/wiki/Battle_of_Gonzales)
1928:
Saint Josemaría Escrivá founded Opus Dei, a worldwide organization of
lay members of the Roman Catholic Church.
(http://en.wikipedia.org/wiki/Opus_Dei)
1950:
Peanuts, a syndicated comic strip by Charles M. Schulz, featuring
Charlie Brown and his pet beagle Snoopy, was first published in major
newspapers.
(http://en.wikipedia.org/wiki/Peanuts)
_____________________
Wikiquote of the day:
A man and a woman Are one. A man and a woman and a blackbird Are
one.
-- Wallace Stevens
(http://en.wikiquote.org/wiki/Wallace_Stevens)