2010: Origin of Life

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Transcript 2010: Origin of Life

Origins of Life
 How old is the universe?
about 15 billion years since Big Bang
 How old is the Earth?
 about 4.5 billion years
 How long has there been life on Earth?
about 3.5 - 4 billion years
 How old is the human species (Homo sapiens)?
100,000 to 200,000 years old
 What do you think conditions were like on early
Earth? Weather? Atmosphere? Appearance?
If earth's history were compressed into
one calendar year, earth forms, cools and
develops an atmosphere during January.
Late January into February sees global
volcanic activity as oceans fill the great
basins. Life begins somewhere in March.
All of human history occurs in the last 7
minutes of December 31, and Columbus
"discovers" America only 3 seconds
before the clock strikes midnight
(midnight = today).
How did life originate?
 Spontaneous Generation
Idea that nonliving material can produce
Recipe for bees:
Kill a young bull, and bury it in an upright
position so that its horns protrude from
the ground. After a month, a swarm of
bees will fly out of the corpse.
Jan Baptista van Helmont’s recipe for mice:
Place a dirty shirt or some rags in an open pot
or barrel containing a few grains of wheat
or some wheat bran, and in 21 days, mice
will appear. There will be adult males and
females present, and they will be capable
of mating and reproducing more mice.
Spontaneous Generation
 Francesco Redi was the first to disprove
this idea.
Spontaneous Generation
 Louis Pasteur went on to
disprove it as well.
 Air can still get in but
microorganisms cannot
So where did life come from???
 Before life can begin, what molecules
would we need to make???
Nucleic Acids
 Living organisms may have arrived from
an extraterrestrial source
Primordial Soup
 Earth’s atmosphere was probably made
up of gases that contained organic
CO2, CH4, NH3…
Primordial Soup
The mix of atmospheric molecules and
Rain washed atmospheric molecules into
the ocean making “the soup”
A particular mix of inorganic chemicals
could have reacted together to produce
small organic molecules.
Amino Acids
Nucleic Acids
Can we prove it?
 Harold Urey and Stanley Miller provided
evidence to support this.