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The Origin of LifeEarly and Modern Ideas
I - OLD IDEA Spontaneous generation or abiogenesis - Life could arise from non-living material.
People observed that decaying matter, for example rotting meat would have maggots after a short period of time, and concluded that maggots would be “born”
from decaying meat.
This idea was popular through
the 1800s.
About 2000
years ago,
a Roman
poet wrote
these
directions.
Van Helmont: (1600s) : He
thought he could produce
mice from wheat and a
soiled shirt.
• Francisco Redi (1600s)- JARS OF MEAT & Maggots EXPERIMENT
He used covered & uncovered jars of rotting meat. After several days, the jars of uncovered meat had maggots, while the jars with the covered meat did not. He reasoned that
flies could not lay eggs
on the meat and therefore
there were no maggots.
Therefore---flies do not
spontaneously arise
from meat.
• Lazzaro Spallanzani’s experiment
(mid 1700s) Flasks of broth experiment
showed that microorganisms will not
grow in boiled & sealed broth, but will grow
If the containers are left open.
Vital force
• John Needham stated that Spallanzani
destroyed the air’s vital force when he
boiled the broth. That is why there were
no microbes.
• Louis Pasteur – (Mid 1800s) His “curved-necked flask” experiment proved that
microorganisms could not arise spontaneously from broth. Air was able to enter the curved-neck of the specially designed flask. Yet, the broth stayed clear.
Pasteur reasoned that microorganisms
are carried to the broth from dust in the
air.
Therefore microbes come from other
microbes and not through a process of
spontaneous generation.
OPARIN’S HYPOTHESIS: Describes how complex organic
compounds may have formed on Earth.
Life beganin the primitiveoceans.
Alexander Oparin(1923-Russian biochemist)
• Elements found in organic compounds were present at Earth & Solar system’s formation.
• Inorganic & simple organic compounds present in the Earth’s primitive atmosphere included inorganic compounds such as:
• NH3 = ammonia gas, • H2O = water vapor,• H2 = hydrogen gas • and a simple organic compound CH4 = methane gas.• (also carbon monoxide, carbon dioxide, Hydrogen cyanide and nitrogen)
Probable no Free Oxygen!
• A great deal of energy was available for chemical reactions. The source of this energy came from: lightning, the sun’s UV radiation , heat from the earth’s crust, volcanic activity, radioactive isotopes etc..
Which this energy present, spontaneous interactions of the simpler molecules formed more complex organic molecules such as: amino acids, sugars, fatty acids, and nitrogenous bases.
• The earth cooled over many years and the water vapor condensed into shallow pools, lakes and then seas.
• Concentrations of the organic compounds increased to form the “primordial soup.”
MILLER –UREY Experiment
supported for Oparin’s Hypothesis
• Stanley Miller (1953) a graduated student under Harold Urey, tested Oparin’s hypothesis .
He set up an apparatus
to simulate the early
Earth conditions. It
suggested how a
mixture of organic
compounds
necessary for life
could have come
from simpler
compounds
present on the
primitive Earth.
It produced organic compounds needed for living things
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