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What is a Microorganism?
What is a Microorganism?
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It is a living organism that is visible (as an individual
organism) only with the aid of a microscope. When
grouped together in chains or clusters, microorganisms
can be seen without a microscope.
Most are single-celled.
As with all living organisms, microorganisms have 6
basic needs:
Food
Water
Air
Temperature of environment
Reproduction
Waste
MICROBE DETECTIVES THROUGH
THE AGES…
HOW FAR HAVE WE COME?
HERE ARE SOME BELIEFS OF THE
PAST…
WHERE DO FROGS COME FROM?
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OBSERVATION: Every year in the spring,
the Nile River flooded areas of Egypt
along the river, leaving behind
nutrient-rich mud that enabled the
people to grow that year’s crop of
food. However, along with the muddy
soil, large numbers of frogs appeared
that weren’t around in drier times.
CONCLUSION: It was perfectly
obvious to people back then that
muddy soil gave rise to the frogs.
WHERE DO MICE COME
FROM?
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OBSERVATION: In many
parts of Europe, medieval
farmers stored grain in barns
with thatched roofs (like
Shakespeare’s house). As a
roof aged, it was not
uncommon for it to start
leaking. This could lead to
spoiled or moldy grain, and
of course there were lots of
mice around.
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CONCLUSION: It was
obvious to them that the
mice came from the moldy
grain.
WHERE DO FLIES COME
FROM?
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OBSERVATION: Since there
were no refrigerators, the
mandatory, daily trip to the
butcher shop, especially in
summer, meant battling the
flies around the carcasses.
Typically, carcasses were
“hung by their heels,” and
customers selected which
chunk the butcher would
carve off for them.
CONCLUSION: Obviously,
the rotting meat that had
been hanging in the sun all
day was the source of the
flies.
For centuries, people based their
beliefs on their interpretations of
what they saw going on in the
world around them without testing
their ideas to determine the
validity of these theories.
FORTUNATELY FOR US, WE HAVE
COME A LONG WAY IN SCIENTIFIC
DISCOVERIES. SOME IMPORTANT
PEOPLE ARE…
ANTONY VAN
LEEUWENHOEK
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The first person to peer into a microscope
was a Dutch cloth merchant named
Antony Van Leeuwenhoek (lay-venhook). A self-taught scientist,
Leeuwenhoek discovered a way to make
magnifying lenses more powerful than
any previously made. Around 1668, he
used a lens no bigger than the head of a
hat pin to create the earliest know singlelens microscope. He looked at scrapings
from his teeth, and saw some tiny
organisms in the sample.
1860 LOUIS PASTEUR
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Louis Pasteur proves
the “germ theory of
disease,” stating
that every infectious
disease is caused
by a specific
microbe.
1867 JOSEPH LISTER
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Joseph Lister
develops antiseptic
methods of surgerysuch as boiling
instruments – to
curb the infection of
wounds.
1928 ALEXANDER FLEMING
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Alexander Fleming
discovers that a
mold called
Penicillium kills
bacteria, paving
the way for the use
of antibiotics.