BIOL 102 Lecture Notes 9-1-16 Chapter 25 (The History of Life on Earth)
BIOL 102 Lecture Notes 9-1-16 Chapter 25 (The History of Life on Earth) BIO 102
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This 1 page Class Notes was uploaded by Zach Notetaker on Sunday September 4, 2016. The Class Notes belongs to BIO 102 at University of South Carolina taught by Mihaly Czako in Fall 2016. Since its upload, it has received 13 views.
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Date Created: 09/04/16
BIOL 102 Lecture Notes 9/1/16 Chapter 25 (The History of Life On Earth) Fossil record shows macroevolutionary changes over large time scales Chemical and physical processes in early Earth may have produced simple cells through sequence of stages: 1. Abiotic synthesis of small organic molecules 2. Joining of these molecules into macromolecules 3. Packaging of molecules into protocells 4. Origin of selfreplicating molecules Evidence not yet convincing that early atmosphere was reducing o Instead of forming in atmosphere, first organic compounds may have been synthesized near volcanoes or deep sea vents o MillerUrey simulated and found that organic molecules could’ve formed w/ various possible atmospheres Hydrocarbons present in deepsea vents, early ocean was acidic Amino acids have also been found in meteorites Abiotic synthesis of Macromolecules o RNA monomers produced spontaneously from simple molecules o Small organic molecules polymerize when concentrated on hot sand, clay, or rock Protocells: o Replication and metabolism are key properties of life and may have appeared in protocells o Protocells may have formed from fluidfilled vesicles in membranelike structure o Vesicles exhibit simple reproduction and metabolism & maintain internal chemical environment different from external First genetic material probably RNA, not DNA RNA molecules called ribozymes have been found to catalyze many reactions Natural selection has produced selfreplicating RNA RNA molecules that were more stable or replicated quicker would have left the most descendant RNA molecules RNA maybe = template for DNA more stable genetic material Few individuals have fossilized Fossil record is biased in favor of species that: o Existed for long time o We abundant and widespread o Had hard parts Absolute ages of fossils determined by radiometric dating Radioactive “parent” isotope decays to “daughter” isotope at constant rate o Each isotope known as halflife time required for ½ parent isotope to decay
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