Download Origin of Life - Hicksville Public Schools

Aim: How do scientists explain the
development of life on earth?
What were the conditions on earth 4.5
billion years ago?1
1) Hot
2) Little Oxygen
3) Abundant Lightning
4) Volcanic Activity
Harsh Early Earth
Primitive Earth’s Energy Source2
As earth cooled, thunderstorms drenched the earth
with water and the oceans
formed. Lightning
provided an energy source
for life to begin.
• Lightening and energy from the sun
provide the energy needed for the
formation of organic compounds.
–Nucleic acids
–Amino acids
–sugars
How did life begin on earth? Formation of
Organic Compounds.3/4
Inorganic
compounds
formed organic
compounds.
Amino Acids,
Nitrogenous Bases,
Monsaccharides,
Fatty Acids
Experiment by Stanley Miller & Harold Urey
Formation of Organic Polymers:3/4
Scientists proved that polymers of organic
compounds (polysaccharides, polypeptides,
lipids and nucleic acids) could have formed
during the conditions of early earth.
“RNA World”
Scientists hypothesize that the first genes were
RNA. RNA served as the both the molecule that
stored the genetic info & the molecule that
directed protein synthesis
Formation of Pre-Cells:5
Experiments show that membranes can
form around organic polymers in a solution
if certain kinds of lipids are present.
**The simplest living organisms are far
more complex than these “pre-cells”
Where did life begin?6
Today’s deep sea vents
are populated with
simple unicellular
organisms that may
resemble some of the
earliest living cells.
First organism on Earth7
Anaerobic
Heterotrophs
Prokaryote Cells
The first organisms on earth were
simple unicellular organisms.
Where did the oxygen come from?8
Some of the early forms of life
developed into unicellular Autotrophs
(they got their energy from the
chemicals in the environment
(chemosynthesis) and later from the
sun and produced oxygen)
Aerobic Organisms 10
Now, that the new atmosphere had
OXYGEN, organisms that could use
oxygen to do cell respiration slowly
developed.
Summary of early evolution
Present day
According to the heterotroph hypothesis,
the first life on Earth was able to?
1. Synthesize its food from inorganic
compounds
2. Feed upon carbohydrates produced by
autotrophs
3. Feed upon available nutrients in the
environment
4. Carry on photosynthesis instead of
respiration.