Genetics - Chemical evolution and Prokaryotic cells...

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Unformatted text preview: Chemical evolution and Prokaryotic cells Chemical Evolution Hypothesis- In 1920s, Oparin and Haldane hypothesized that conditions on early Earth, in particular the reducing atmosphere, lightning and intense UV radiation, favored the synthesis of organic compounds.- Simple molecules were present in the atmosphere of ancient Earth, including carbon monoxide (CO), carbon dioxide (CO 2 ), hydrogen (H 2 ), ammonia (N H 3 ), water (H 2 O), and nitrogen (N 2 ). - The energy in sunlight drove reactions among the simple molecules, resulting in compounds such as formaldehyde (H 2 CO) and hydrogen cyanide (HCN). - When heated, compounds containing single carbon atoms reacted to form more complex molecules containing carbon-carbons, including acetaldehyde, glycine, and r ibose. M iller-Urey Experiment (Know how to explain) Hypothesis- The conditions on early Earth favored the synthesis of organic compounds from inorganic compounds. Experiment- The experiment used reducing compounds, water (H2O), methane (CH4), ammonia (N H3), and hydrogen (H2) to simulate early earth.- Heated water simulated the ocean, some oceanic water vaporized.- Electrode discharges sparks simulate lightning- Water vapor cooled and condensed and flowed back to small flask where it boiled again. - I n this way water vapor circulated continuously carrying with it any organic compounds formed to the ocean. Compounds formed in M iller Urey experiment (Results)- Amino acids, sugars, liquids, HCN, H2CO were formed Conclusion- The conditions in prebiotic environment of the early Earth were capable of producing complex biochemical molecules necessary for early life to begin. Abiotic synthesis of polymers- Small organic molecules- Polymerize when they are concentrated on hot sand, clay, or rock- These polymers may have served as weak catalysts for a variety of reactions. Emergence of life requires a vast assortment of macromolecules. Protobionts - Collection of abiotically produced molecules surrounded by a membrane.- Organic ingredients in the lab have been shown to assemble into liposomes that indicate Protobionts may occur spontaneously.- Life requires accurate replication and metabolism. RNA r ibozymes- May have been the first Protobionts- They can self-replicate and catalyze reactions- Can hold genetic information The Universal T ree of Life - Last com mon ancestor of all living things- Possible fusion of bacterium and archaean, yielding ancestor of eukaryotic cells- Symbiosis of mitochondrial ancestor with ancestor of eukaryotes- Symbiosis of chloroplast ancestor with ancestor of green plants The Three Domains of Life- At the highest level, life is classified into three domains Bacteria, Archaea and Eukarya- Domain Bacteria and domain Archaea consists of prokaryotes- Domain Eukarya, the eukaryotes- Includes the various protist kingdoms and the kingdoms Plantae, Fungi, and Animalia Bacteria cell structures Basic bacteria structure (Know how to draw)- Flagella movement- Cell me mbrane controls substance entry and exit...
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This note was uploaded on 08/18/2011 for the course BIO 1406 taught by Professor Bostic during the Spring '09 term at Austin Community College.

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Genetics - Chemical evolution and Prokaryotic cells...

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