Transcript 4 Early Earth Notes

Early Earth Notes
The earth was formed 4.6 billion years ago!
So what was it like?
Early earth conditions (4.6 BYA)
o VERY HOT!
o Volcanoes and Meteors bombarding the earth
o NO atmospheric Oxygen
o Gases in the atmosphere
o Methane gas (CH4)
o Ammonia (NH3)
o Nitrogen (N)
o CO2 (carbon Dioxide)
o H2O (water vapor)
o Hydrogen gas (H)
Early Earth Landscape:
How did life originate?
 First step towards life…
 ORGANIC MOLECULES must be formed
Methane gas (CH4)
Ammonia (NH3)
Nitrogen (N)
CO2 (carbon
Dioxide)
H2O (water vapor)
Hydrogen gas (H)
Monomers of life…
• Monosaccharides
• Amino acids
• Nucleotides
• Fatty acids
How did that happen?
 Alexander Oparin
 Life began in the oceans
 Energy from the sun, lightning, and Earth’s heat
triggered chemical reactions to produce small organic
molecules
The experiment to back it up…
 Harold Urey and Stanley Miller provided
evidence to support this.
What did they discover?
Ocean
Early
Atmosphere
Gases
Methane gas (CH4)
Ammonia (NH3)
Nitrogen (N)
CO2 (carbon Dioxide)
H2O (water vapor)
Hydrogen gas (H)
ENERGY
Monomers of life…
• Monosaccharides
• Amino acids
• Nucleotides
• Fatty acids
Methane gas (CH4)
Ammonia (NH3)
Nitrogen (N)
CO2 (carbon Dioxide)
H2O (water vapor)
Hydrogen gas (H)
Monomers of life…
• Monosaccharides
• Amino acids
• Nucleotides
• Fatty acids
Chemical Evolution
Miller Urey BIG IDEA…
 Simulated early Earth atmosphere and added
ENERGY
 After a week, they found several kinds of amino
acids, sugars, and other small organic molecules
 Evidence supported Oparin’s hypothesis!
 Life began in the oceans and Energy from the
sun, lightning, and Earth’s heat triggered
chemical reactions to produce small organic
molecules
Soups On!
 Primordial soup- where life began???
Primordial Soup
 These molecules were washed into the oceans,
mixing together, but how did that create the first
CELL????
How did life originate?
 Spontaneous Generation
 Idea that nonliving material can produce life
 Ex- maggots come from rotting meat- YUCK!!!
Spontaneous Generation
 Francesco Redi was the first to try to
disprove this idea.

He showed that FLIES lay eggs on the meat to
produce maggots.
NOT OVER YET…
 Some still thought bacteria, mold, etc could
spontaneously generate in broth…as long is was left
open to air. (Why- what else is in the air???)
Spontaneous Generation
 Louis Pasteur went on to disprove that as well.
He put a curved tube on the broth
so air could still get in but not
bacteria! NO GROWTH!
SO HOW DID THE FIRST CELL ORIGINATE?
Meteorites
 Maybe a meteorite brought it here from another
planet?
PROTOCELLS?
 Small, ordered structures that carry out some life
activites like growth and division.
 Basically a clump of amino acids with a membrane
 Could have evolved into cells over time…
So what happened next?
 Life on earth is one
big extended
family
In aHistory
single day.
of the
Earth
Courtesy: NASA / Goddard Space Flight Center
12.00 to 4.00am
 “The Big Bang”
 No life
 A planet with
poisonous gases
in the air, no soil
and a hot sea.
4.00am to 8.00pm
 Single celled organisms, called stromatolites, begin
to produce oxygen.
Just before 8.30pm
 First marine plants
8.50pm
 Jellyfish and simple
marine organisms
Just after 9.00pm
 Trilobites and creatures of the Burgess Shale
10.00pm
 Plant life of the
carboniferous and
the first land
creatures.
11.00pm to 11.45pm
 Reign of the Reptiles – Dinosaurs Rule!
1 minute and 17
seconds to midnight
 First humans appear.
Clock
analogy for
some key
events in
evolutionary
history
So… what do I need to know?
First Cell (3.5 BYA)
 Single celled organism
 Prokaryotic
 Archaebacteria (like extreme conditions)
 Anaerobic
 (Don’t require O2)
 Chemoautotrophic or
heterotrophic

(get energy from ‘eating’ or
making chemicals)
Photosynthesis Begins!
 Photosynthetic Bacteria
 Prokaryotic, single celled organisms
 3.2 BYA
Cyanobacteria are
photosynthetic prokaryotes
that are still present today
 produced oxygen.
First Euk!
 Eukaryotic single- celled organisms evolved next.
How did cells get organelles???
 One theory says that one cell engulfed others and
they eventually evolved to be one cell…

(called Endosymbiotic Theory…can you break it down???)
Evolution of Life
Stronger together!
 Multicellular (euk) aquatic organisms evolved next
 (.65 BYA- don’t need to know date)
Oxygen began accumulating in the atmosphere
about 2.7 billion years ago.
What gas greatly
reduced over time as
the O2 levels
increased?
Carbon dioxide!!!
As photosynthetic
organisms evolved,
they used CO2 and
produced O2
Life on Land!!!
 Life finally moves onto land
 (0.43 BYA)
Some
major
episodes in
the history
of life.