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I. Changes Through Time. A. The Beginning of Life. 1. Origin of the Universe (13.7 BYA). Many theories exist. b) Scientists favor the Big Bang Theory which state that the universe began as a dense concentration of matter smaller than a speck of dust which exploded outward violently.
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1. Origin of the Universe (13.7 BYA) • Many theories exist b) Scientists favor the Big Bang Theory which state that the universe began as a dense concentration of matter smaller than a speck of dust which exploded outward violently
Great Explanations of The Big Bang Theory appear in these books:
2. Origin of the Sun (10 BYA) • Clouds of molecules, made of hydrogen gas, began to grow in mass which increased their gravity, which in turn, attracted more hydrogen to increase their mass b) These clouds increased to such a huge mass, that it’s gravity smashed hydrogen molecules together, triggering a Fusion Reaction. We call these fusion reactions clouds Stars and one formed our Sun
3. Origin of Earth • Clouds of matter caught in the Sun’s gravitational field began forming Planets • Solid matter collected into a dense core and radioactive decay melted the matter into a ball of molten rock that we call Earth
c) Earth could not support life at this time. • Tidal waves of Lava • Poison gas atmosphere • Deadly ultraviolet rays • Constant meteorite bombardment • Frequent earthquakes
4. Origin of Life (3.5 BYA) a) The heat of the earth slowly radiated away and the atmosphere cooled below the boiling point. Rain formed theoceans
Abiogenesis- Spontaneous generation of Life. Abiogenesis is NOT evolution Russian Biochemist Alexander Oparin introduced a plausible theory of chemical development of life in 1927
b) Oparin’s Hypothesis • The early atmosphere contained hydrogen, Methane, Ammonia and Water vapor • Violent atmospheric conditions caused much lightning; heat from molten rock, and ultravioletradiation from the sun provided energy for chemical reactions to take place • Organic molecules such as Amino acids, lipids and nucleic acids accumulated in the oceans forming an organic soup • The organic compounds developed into the first cells which might have resembled anaerobicbacteria
5. Global Famine and Toxic Waste • The first cells had plenty to eat; however, as population size increased, food decreased (Global Famine) • Fortunately, high amounts of ultraviolet radiation caused a high rate ofmutationand cells capable ofphotosynthesisdeveloped • Thesecynobacteriachanged the earth’s atmosphere by adding oxygen • Pure oxygen is toxic and highly reactive and it built up in the atmosphere until it threatened all live on earth (toxic waste) • Mutations created cells capable of respiration which converted the oxygen to water
B. Evidence for Oparin’s Hypothesis 1. Stanley Millers Experiment • Miller created an apparatus to simulate the conditions on early earth • After running his “primitive earth machine” for a few days, miller found his “ocean” teeming with amino acidsthe building blocks of protein!
2. Sidney Fox Experiment • Fox heated and cooled amino acids. And found they formed “cell-like” clump calledcoacervates. • Coacervates carry on limited enzyme activity
3) Leslie Orgel • Orgel proved that nucleotides of DNA and RNA can assemble under the conditions of early • Proposed that RNA was the first genetic material because it’s can be auto catalytic
4) David Deamer • Deamer mixed lipid with DNA and dehydrated them and rehydrated them and found that they would form membranes around the DNA
What does DNA and RNA polynucleotides with protein catalyzing chemical reactions in a lipid membrane remind you of? A cell of course! But, scientists have only produced Coacervates in the lab
DNA replication requires enzymes and DNA is required to make enzymes. Therefore, current theory suggests that the first genetic material was RNA because it can be auto catalytic (RNA could catalyze its own replication.) But, replication produces a complementary strand, not a coding strand, so two replications would be required.
C. Evidence of Evolution 1. Direct evidence of Evolution comes from the fossil record Scientists who interpret the fossil record are called paleontologists
Fossil Record • Fossils- any evidence of a once living thing • Fossil formation (a sequence of improbable events) most often occurs in sedimentary rock, where sand under great pressure turns to rock
Types of Fossils Imprints Casts Petrified Molds
3) Types of Fossils • Imprints- formed by impressions in rock • Molds- depressions in rocks shaped like the organisms • Casts- where molds are filled with other material leaving a fossil shaped like the original structure • Petrified fossils- where parts of an organisms are replaced by minerals
b) Determining the Age of Fossils • By their position in the layers of sedimentary rock • By using radioactive isotopes- materials that decompose into decay elements at a constant rate called a half-life • Carbon 14 half-life 5730 • Uranium 238 half life 4.5 billion
a. Comparative Biochemistry Organisms with similar protein structure and similar DNA sequences are more closely related than organisms with different protein structure and different DNA sequences
Examine the following DNA sequences. Which two of the three organisms is most closely related? Organism A: GGT CTC AAT GTA ATC CAA TCC AGG Organism B: GGT CAC ATT GTA ATG CAA TCG AGG Organism C: GGA CTC ATT GTA ATC CGG TCC AGC A & B Matches: 20 A & C Matches: 19 B & C Matches: 17 A & B are most closely related
b. Homologous Bone Structures Similar structures found in different organisms suggests a common ancestry
c. Embryological Evidence Organisms that develop similarly have common genetic material which controls development which in turn suggest common ancestry
