Origin Of Life
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Chapter 19
Origin of Life
Origin and History of Life
Theories on Origin of Life
Philosophers and scientists from time immemorial have attempted to explain how and where life originated on this planet earth. Today, earth is the only planet where life exists. However, when the earth was formed about 4.8 billion years ago, there was absolutely no sign of life on earth. The first form of life is said to have appeared about 3.8 billion years ago.
Theory of Special Creation all the different forms of life that occur today on planet earth, have been created by God, the Almighty Special creation theory believes that the things have not undergone any significant change since their creation.
Origin and History of Life
Theories on Origin of Life Theory of Spontaneous Generation Assumed that living organisms could arise suddenly and spontaneously from any kind of non-living matter believed that dead leaves falling from a tree into a pond would transform into fishes and those falling on soil would transform into worms and insects This theory was disapproved, as scientists gave definite proof that life comes from pre-existing life
Spallanzani (1765)
Pasteur (1864)
Origin and History of Life
Theories on Origin of Life Theory of Catastrophism simply a modification of the theory of Special Creation
It states that there have been several creations of life by God, each preceded by a catastrophe resulting from some kind of geological disturbance
since each catastrophe completely destroyed the existing life, each new creation consisted of life form different from that of previous ones.
Origin and History of Life
Theories on Origin of Life Theory of Panspermia life has reached this planet Earth from other heavenly bodies such as meteorites, in the form of highly resistance spores of some organisms.
This theory lacks evidence, hence it was discarded.
Arrhenius, 1908
Origin and History of Life
Theories on Origin of Life 1923
1928
Theory of Chemical Evolution Origin of life on earth is the result of a slow and gradual process of chemical evolution that probably occurred about 3.8 billion years ago.
According to this theory: Spontaneous generation of life, under the present environmental conditions is not possible. Earth's surface and atmosphere during the first billion years of existence, were radically different from that of today's conditions.
The primitive earth's atmosphere was a reducing type of atmosphere and not oxidising type.
The first life arose from a collection of chemical substances through a progressive series of chemical reactions.
Solar radiation, heat radiated by earth and lighting must have been the chief energy source for these chemical reactions.
Miller’s & Urey’s Apparatus & Experiment.
Miller-Urey Experimental Results
Theory about the Origin of Cell
Origin of the First Cell(s)
The Earth’s First Organisms?
Life’s origin • Organic compounds • 4 billion years ago: Prokaryote (Prokaryotic cell): first living cell – cellular organism without cell membrane • 2 billion years ago: Eukaryote (Eukaryotic cell): more complex, with cell membrane. Have mitochondria which can produce energy through respiration.
Strat a
Ending Slide Chapter 19
Origin of Life
Origin of Life
Origin and History of Life
Theories on Origin of Life
Philosophers and scientists from time immemorial have attempted to explain how and where life originated on this planet earth. Today, earth is the only planet where life exists. However, when the earth was formed about 4.8 billion years ago, there was absolutely no sign of life on earth. The first form of life is said to have appeared about 3.8 billion years ago.
Theory of Special Creation all the different forms of life that occur today on planet earth, have been created by God, the Almighty Special creation theory believes that the things have not undergone any significant change since their creation.
Origin and History of Life
Theories on Origin of Life Theory of Spontaneous Generation Assumed that living organisms could arise suddenly and spontaneously from any kind of non-living matter believed that dead leaves falling from a tree into a pond would transform into fishes and those falling on soil would transform into worms and insects This theory was disapproved, as scientists gave definite proof that life comes from pre-existing life
Spallanzani (1765)
Pasteur (1864)
Origin and History of Life
Theories on Origin of Life Theory of Catastrophism simply a modification of the theory of Special Creation
It states that there have been several creations of life by God, each preceded by a catastrophe resulting from some kind of geological disturbance
since each catastrophe completely destroyed the existing life, each new creation consisted of life form different from that of previous ones.
Origin and History of Life
Theories on Origin of Life Theory of Panspermia life has reached this planet Earth from other heavenly bodies such as meteorites, in the form of highly resistance spores of some organisms.
This theory lacks evidence, hence it was discarded.
Arrhenius, 1908
Origin and History of Life
Theories on Origin of Life 1923
1928
Theory of Chemical Evolution Origin of life on earth is the result of a slow and gradual process of chemical evolution that probably occurred about 3.8 billion years ago.
According to this theory: Spontaneous generation of life, under the present environmental conditions is not possible. Earth's surface and atmosphere during the first billion years of existence, were radically different from that of today's conditions.
The primitive earth's atmosphere was a reducing type of atmosphere and not oxidising type.
The first life arose from a collection of chemical substances through a progressive series of chemical reactions.
Solar radiation, heat radiated by earth and lighting must have been the chief energy source for these chemical reactions.
Miller’s & Urey’s Apparatus & Experiment.
Miller-Urey Experimental Results
Theory about the Origin of Cell
Origin of the First Cell(s)
The Earth’s First Organisms?
Life’s origin • Organic compounds • 4 billion years ago: Prokaryote (Prokaryotic cell): first living cell – cellular organism without cell membrane • 2 billion years ago: Eukaryote (Eukaryotic cell): more complex, with cell membrane. Have mitochondria which can produce energy through respiration.
Strat a
Ending Slide Chapter 19
Origin of Life
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