Transcript The Origin of Life

 The
solar system is estimated to be 6.6
billion years old.
 Earth
old.
is estimated to be 4.1 billion years
 NH3
Ammonia
 CH3 Methane
 CO2 Carbon Dioxide
 N2 Nitrogen
 O2 Oxygen
.1%
.1%
92.2%
5.1%
0%
 NH3
Ammonia
 CH3 Methane
 CO2 Carbon Dioxide
 N2 Nitrogen
 O2 Oxygen
Trace
Trace
.03%
78.1%
20.9%
 The
absence of oxygen was a key factor
in the beginning of life.
 Scientists
may never now exactly when
and how life originated on earth, but they
have several hypothesis based on what
they know today.
 Based
on this information scientists infer
that life originated in four steps.
 1. Inorganic(nonliving)
matter
Simple organic molecules
 2. Simple
organic molecules
Polymers(chains of organic molecules)
 3. Polymers
 4. Protocells
Protocells
Cells
 Inorganic(nonliving)
organic molecules.
matter
Simple
 Organic
Molecules- A compound that
contains carbon and is usually associated
with living organisms.
 The
hypothesis of Chemical Evolution,1924:
Alexander Oparin formed the first theory on
how organic molecules might have been
formed.
 He
Hypothesized that energy in the UV
radiation and lightning stimulated
chemical reactions in the ancient
atmosphere. These random chemical
reactions, occurring over millions of
years, produced organic molecules.
 Stanley
Miller and Harold Urey performed
a test on Oparins hypothesis, 1953: They
made a model of the ancient atmosphere
by mixing gases in a reacting chamber
with electrodes simulated the lightning.
 After
one week, liquid was collected and
analyzed, and they found amino acids
and other organic molecules had formed!
 Miller
and Urey showed that Chemical
Evolution could have occurred under the
conditions modeled by their experiment.
 Other
scientists have tested the Chemical
Evolution hypothesis with different gases
and energy sources and have produced
not only amino acids but also ATP, DNA,
and RNA.
 Simple
organic molecules (monomers)
need to organic into complex organic
molecules or chains of monomers called
polymers.
 Example: Protein
polymer is composed
of a chain of amino acids. (Complex
Molecule) (Simple Molecule)
 Two
Events must occur for polymers to
form:
• The monomers must be close enough to react
with one another.
• Monomers must chemically bond.
 Theories
of how this occurred:
• Chance meetings in the early seas.
• They formed in evaporating puddles of water.
• Developed in clay formations.
 The
formation of the cell membrane,
needed to separate internal environment
from external environment so chemical
reactions of life could occur inside the
cell.
 Microspheres-
Protein and water
bubbles, look and behave like cell
membranes. Could divide, but could not
pass traits to offspring.
 At
some point in life protocells absorbed
nucleic acids (DNA, RNA). Now they could
reproduce and transfer genetic information
of offspring.
 As
organic compounds increases in the
protocell, this would enable essential
chemical reactions and energy production
similar to metabolism. It could be truly
called a living thing.
 The
First Cell