Transcript Ch. 14-Life History Lecture #2

The Origin of Life
14.2
I. SPONTANEOUS GENERATION
A. Belief that living things came
from non-living things
1. Ex: Mold in my fridge came
from the tomato it was found on
2. People believed this prior to
the 1600’s
I. SPONTANEOUS GENERATION
B. Francesco Redi
disproved
spontaneous
generation of large
organisms
1. See Pg. 401
I. SPONTANEOUS GENERATION
C. Louis Pasteur disproved
spontaneous generation of
microorganisms using broth
and different types of flasks.
1. Mid 1800’s
II. So How Did Living Things Form?
A. Biogenesis- The idea that
living things only come from
other living things
1. Birth or Mitosis
II. So How Did Living Things Form?
B. Primordial Soup Theory
1. Suggested by Alexander
Oparin & John Haldane in 1920
2. Organic molecules (amino
acids) could have formed from
the gases in the primitive
atmosphere
a)
CO2
methane
nitrogen
+ water vapor
Amino Acids
(simple organic molecules)
a)All living things
contain carbon atoms
(organic)
b) Lightning could
have caused
chemical reactions in
the atmosphere
II. So How Did Living Things Form?
C. Urey & Miller,1953
1. Re-created earth’s
primitive atmosphere
2. Used electricity to
imitate lightning
3. Simple organic
compounds (amino
acids) formed
II. So How Did Living Things Form?
4. Rain washed the amino acids
into the oceans making
“primordial soup” of the organic
molecules
5. Small pools of water heated
from the sun cause amino
acids to link into protocells
II. So How Did Living Things Form?
D. Protocell- Large, membraned
structure that caries out some
life processes such as cell
division.
E. From protocells came
prokaryotes
III. The First Cells
A. First prokaryotes were similar
to today’s archaebacteria
1. Lived in extreme
conditions
2. Most were heterotrophs
III. The First Cells
3. Some were capable of
photosynthesis (autotrophs)
a) cyanobacteria
b) More oxygen in atmosphere
created the ozone layer
2. Aerobic eukaryotes can now
evolve
IV. Eukaryotes Evolve
A. Endosymboint Theory (pg. 407)
1. A prokaryote ingested (ate)
some aerobic bacteria (also
prokaryotes)
2. The bacteria provides
energy for the prokaryote
IV. Eukaryotes Evolve
3. These bacteria evolve into
mitochondria creating an animal
cell
4. Some prokaryotes also ingested
cynobacteria that contained
photosynthetic pigments that
evolved into chloroplasts creating a
plant cell