Download Wednesday, February 22

Wednesday, February 22
The Origin of Life
“Early Earth”
• Earth’s age is estimated to be 4.5 b.y.o.
• Early Earth was made of super hot liquid rock
• There was no ozone layer, so no protection
from UV radiation
• In addition to harmful
UV radiation, the
atmosphere was a mix
of toxic gases
• Not a great place to live
It started getting better
• After hundreds of millions of years, Earth
began to cool and become solid
• Water collected at the surface, creating the
oceans
• The first life is estimated to have appeared
between 3.8 and 2.5 b.y.o.
• That’s nearly 1-2 billion years after Earth was
formed.
How Did Life “Pop Up” in this Early
Earth?
• A couple scientists decided to re-create Early
Earth conditions and produce organic
molecules
• Scientists were Stanly L. Miller and Harold C.
Urey.
• They began working in 1953 at the University
of Chicago
Miller-Urey Experiment
• After replicating Early Atmosphere, the
experiment was able to produce many organic
molecules, including AMINO ACIDS
• This supported the hypothesis that early
atmosphere could produce the building blocks
of life
• http://www.youtube.com/watch?v=iahBQolX
QH8
Where Did Life Begin?
• Scientists agree that life formed as the Earth
was cooling
• But there are several different theories as to
WHERE life started
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Ocean Ridge
Under Frozen Seas
Deep in the Earth’s Crust
Within Clay
In Deep Ocean Vents
In Deep Sea Vents
• You Tube Video - Lets try FireFox
Early Life Forms
• Earliest forms of life in the fossil record date
back 3.5 billion years ago
• Early organisms were small, single-celled,
aqueous prokaryotes
• Lacked external appendages, nucleus, and
limited internal structures (these were
prokaryotes, remember!
Prokaryotes
• Two groups of prokaryotes:
• Archaebacteria
• Bacteria
Archaebacteria
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Archaebacteria - Inhabit extreme conditions
habitats high in toxic gases
extremely salty habitats
extremely hot habitats
Bacteria
• Bacteria – make up most of the prokaryotes
alive today
Eukaryotes
• These more complex cells appeared about 1.5
million years ago
• There are three main innovations in the
development of Eukaryotic Cells
• Complex structures
• Sexual Reproduction
• Multi-cellularity
Complex Structures
• Simple structures within prokaryotes are
thought to have been developed into more
sophisticated structures in eukaryotic cells.
• Eukaryotic cells engulfed a prokaryotic cell to
obtain their organelles
• Phagocytosis – “to devour”
• One example = Mitochondria
Mitochondria have 2 layers (1 & 2)
Sexual Reproduction
• Most eukaryotic cells reproduce sexually
• Results in recombination of genetic material!
• This is a key requirement for evolution
resulting in the large diversity of eukaryotes
Multi-Cellularity
• Single eukaryotic cells formed colonies
• Individual cells begin performing specific tasks
• Eventually these colonies become individual
organism! (eukaryotic cell!)
Remember yesterday…
• King Philip Came Over For Good Soup
• Kings Play Chess On Funny Green Squares
• These are all below the classification of
DOMAIN
– Three Domains: Archaea, Bacteria, Eukarya
• Below those three, 6 Kingdoms
• Domain Archaea
– Kingdom Archaebacteria
• Domain Bacteria
– Kingdom Bacteria
• Domain Eukarya
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Kingdom Protista
Kingdom Fungi
Kingdom Plante
Kingdom Anamalia