I. How Did Life Begin?. Prior to the 17 th century: 1. Spontaneous Generation : The belief that living things could come from non-living things. Francesco Redi (1668) Italian scientist. Attempted to discredit Spontaneous Generation. Experimented to prove that maggots came from flies.
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Prior to the 17th century:
1. Spontaneous Generation:
The belief that living things could come from non-living things.
1668 – Experiment showing how maggots come from flies
Experimented with spontaneous generation of microorganisms.
1. Created meat broth
2. Boiled broth to kill microorganisms
3. Capped some flasks and left others open.
Opponents of his study claimed that he overheated the samples…
Destroying the VITAL FORCE
*The conclusions of Pasteur, brought about the theory of BIOGENESIS – Living things come from other living things
As millions of years passed, a large amount of material collapsed to the center and created the sun.
Around 4.6 billion years ago, the earth and some of the other planets were formed.
As earth cooled, water vapor in the air condensed to form water and the first oceans.
3.8 to 3.9 billion years ago.
Estimate the age of an object by measuring its content of radioactive isotopes.
Unstable and “decay” over time.
The time that it takes for a radioactive isotope to decay by one half
The oldest evidence of life on the earth is found in rock estimated to be 3.5 billion years old.
The evidence shows in the form of FOSSILS.
The first fossils were referred to as MICROFOSSILS, ancient prokaryotic cells.
1. Formation of Simple Organic Compounds
-In 1953, Americans, Stanley MillerandHarold Urey, set up an experiment that was based on Oparin’s theory.
Ammonia and Methane were released from volcanoes into bubbles
Bubbles rise to the surface and burst
-Similar mechanisms may have led to the formation of carbohydrates,lipids, and nucleic acids
3. Concentration and Enclosure
Proteins clump together to form microscopic droplets…
Includes Amino Acids and sugars
4. Evolution of Growth, Metabolism, and Reproduction
Coacervatesand microspheres lack the complexity of living cells …
-They can grow
-They can bud
A special type of RNA was discovered to be able to act like an enzyme
They can replicate themselves
Research indicates life may have started with RNA
Scientists hypothesize that the first cells were:
B. The First Eukaryotes
1) Those organism that could bond oxygen to other compounds survived
- beginning of aerobic respiration.
2) Ozone (O3) was created
ACQUIRED TRAITS: explanation for species change.
EXAMPLES: web feet, giraffe neck, tails
“USE and DISUSE”
Darwin proposed a mechanism for evolution
Natural Selection: occurs because of ADAPTATIONS
Published a book: “On the Origin of Species”1859, 1 year after Alfred Wallace (same basic ideas)
“Human populations are able to increase faster than the food supply can”– Thomas Malthus 1798
Descent with modification:
Newer life forms appearing in the fossil record are modified versions of the old species
Modification by Natural Selection:
Mechanism for how evolution can occur.
The environment affects individuals differently
Some traits provide an advantage
Populations ADAPT as the proportion of favorable genes increases
FITNESS: Single organisms genetic contribution to the next generation.
Favorable traits provide an ADAPTIVE ADVANTAGE
Inherited traits that have become popular due to a selective advantage
Based on 4 major points….
2. Some individuals are better suited for their environments
The Fossil Record:
Preserved or mineralized remains or imprints of an organism that lived long ago
A film of carbon remains after other elements of an organism have decayed
created by the impression of a shape/track
sediment fills in a cavity left by a fossil
1. Position within sedimentary rock
1) Evidence of Common Ancestry
-Organisms that are similar in structure had a common ancestor
but function the same
-Examine biochemical compounds within organisms
3. Vestigial Organs:
Organs that are seemingly functionless
Compare organisms at various stages of development