ORIGIN AND EVOLUTION OF LIFE
I.
II.
I. INTRODUCTION
A. Common origin of life explains unity of all living things
B.
Life is physical & chemical phenomenon
C.
Earth influenced development of life
D. Life influenced atmosphere & surface of earth
CHEMICAL EVOLUTION
A. Primitive earth
1. Formed 4.6 billion years ago
2. N2 ; H2 ; CO2 ; methane: CH4 ; water vapor
3. No O2 in atmosphere
4. Later, water vapor  oceans
5. Reducing atmosphere encourages organic molecule formation(adds e- to reactions)
B.
Oldest fossils - 3.8 billion yrs old (Archean Era)
1. 1920's: Oparin hypothesized: energy (lightening, UV, volcanic)+
gases (N2, H2, CO2, CH4, H2O)  organic molecules (amino acids,
sugars, nucleotides)
2. 1953: Stanley Miller's experiment supported Oparin
3. Modern Hypotheses
a.
DNA  RNA  Proteins: self-replicating system
b.
Polymers (large organic molecules)  cell membrane
C.
Protocell
1. (DNA  RNA  protein) + membrane
2. Heterotrophs
3. Fermenters or Anaerobic Electron Transport (Glycolysis)
4. Photosynthesis began in some
D. Prokaryotic (3.2 - 3.8 billion yrs. ago)
1. Photosynthetic cyanobacteria produced O2
2. 2.5 billion yrs ago (Proterozoic Era)
3. Atmosphere: changed from reducing to oxidizing: causes
breakdown of organic molecules
a.
Food in ‘primordial soup’ ran out for heterotrophs
b.
O3 - ozone blocks UV (loose steady source of "super"
energy)
c.
Now only life from life - Principle of Biogenesis
E.
Eukaryotic
1.2 billion yrs ago
1.
Colonial
2.
Multicellular: Differentiated function
1st probably were sex cells
Cambrian Period of Paleozoic Era (600 million yrs ago) - burst of
diversity
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III.
SIX KINGDOMS
A.
IV.
Archaebacteria (Domain Archaea)
1. Prokaryotic
2. Single celled
3. Ancestors of the Eubacteria, Protista, Plantae, Fungi and Animalia
Kingdoms
B.
Eubacteria (Domain Eubacteria)
1. Prokaryotic
2. Single celled
3. Includes heterotrophic bacteria & cyanobacteria (blue-green algae)
C.
Protista
1. Eukaryotic
2. Most single celled
3. Aquatic
4. Three major lineages
a.
Algae: ancestors of the Plantae Kingdom
b.
Water and slime molds: linked to ancestors of the Fungi K.
c.
Protozoans: ancestors of the Animalia Kingdom
D. Fungi
1. Eukaryotic
2. Mostly multicellular
3. Heterotrophic by absorption
4. Nonmotile
5. Terrestrial
E.
Plants
1. Eukaryotic
2. Multicellular
3. Photosynthetic (most)
4. Nonmotile
5. Internal protection of embryo
6. Terrestrial (most)
F.
Animals
1. Eukaryotic
2. Multicellular
3. Heterotrophic by ingestion (most)
4. Motile by muscle fiber
5. Terrestrial: internal protection of embryo
6. Aquatic: no internal protection of embryo in primitive species
SUMMARY
inorganic  small organic  macro-organic  protocell  prokaryotic
 eukaryotic  colonial  multicellular
V.
HOMEWORK (See outline of homework for details)
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