Theories of Origin of Life briefly.

Nemeth Aurora By Nemeth Aurora, 12th Dec 2013 | Follow this author | RSS Feed
Posted in Wikinut>Guides>Science>Biology>Biochemistry

3 famous theories are described briefly.No religious theories.

Theory of Spontaneous Generation and Theory of extra-terrestrial Origin.

(1.)Theory of Spontaneous Generation.
Majority of people until 19th century,belived that some spicies are originated from non living things.They belived that animals like worms,insects,rats,snails,leeches are born out from garbage spontaneously.Aristotle also belived in spontaneous theory.But from 17th century some scientists questioned about theory.But they were humilated by society.

In 1665 Rober Hooke reported his observation about cells and in 1976 Antony Van Leeuwenhoeck published his observation about micro organisms.These were belived as evidences to prove Spontaneous Generating Theory.Micro organisms were considered as too simple for reproduction.

Some scientists tried to find experimental evidences against this theory.In 1668,Francesco Redi brought first experimental evidence against this theory.He showed that maggots will not appear if dead bodies,meat,fish were covered tightly.He told that maggots are born out of eggs laid by flies.

Lazzaro Spellanzani in 1768 showed that micro organisms also carried by air.He proved that well boiled broths are free of microbes and microbes would not be seen again if they are air proof.But some Jhon Needham did not agree this.They told that air is an essential factor for origin of life.

In 1858,Rudolf Virchov brought Theory of Biogenesis agains Theory of spontaneous generation.He told that 'every organism exists from pre existed organism'.

In 1861,Louis Pasteur brought evidences to sweep out Theory of Spontaneous Generation.He filled sterilized broth in a swan neck flask(A flask with a very thin bend neck like a swan neck) and showed that no life will origin inside after keeping few days though air entered the flask.He proved that Theory of Spontaneous Generation is a lie.

(2)Theory of Extra-Terrestrial Origin.

Also called The Cosmozoic Theory.This theory shows that life was brought to Earth from outer space by asteroids or any other extra-terrestrial objects.These objects transpored organisms or materials needed for origin of life.Also some amino acids and some organic molecules have been found in asteroids.But they are not enough to confirm the theory.Some scientists belive the theory nowadays.

Theory of Biochemical Evolution.

Approved by many
scientists.They belive that life
originated naturally on Earth by
organic materials created by
inorganic materials according to
natural laws of physics and
chemistry.Also called The Theory
of Abiogenesis.Charles Darwin
also belived that life was
originated in a hot water pond
filled with Ammonium
ions,Phosphates and many salts.
Most acceptable theory about
abiogenesis was brought by
Russian scientist Alexander
Oparin and British scientist
J.B.S.Haldane in 1920.They
presented it independantly.
According to them,early Earth's
atmosphere was Oxygen gas
free.Simple gases like
CH4,H2O,CO2,NH3 were
abundant. UV radiation and
electric discharged made these
gases to produce simple organic
materials.Due to these materials
ocean was like a soup.It is called
the 'Primordial Soup'.These
organic materials were adsorbed
to surfaces like clay and
complexes were built.These
complexes were covered with
membranes.They were the
foundation for life.They are
called 'Coacervates'.Later they
got the ability for growth and
division.Gradually cells evolved
from coacervates.
In 1953,Stanley Muller and
Harold Urey set up an
experiment to prove this
theory.They duplicated the early
atmosphere in a flask.Flask was
filled CH4,NH3,H2 and
H2O.Then discharged charges
into it.After,there were many
organic materials including
amino acids in the flask.Later this
experiment was done by many
scientists.They showed that
nucleotides,DNA bases are also
produced in experiment.


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