biology 1620 notes - CHAPTER 26 8/26/09 Origins of life...

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CHAPTER 26 8/26/09 Origins of life Earth forms 4.6 BYA from molten rock. Oceans formed as earth cooled from H2O condensation. 2 H2O sources: 1. Comets 2. H20 vapor from volcanoes 3 energy sources 1. UV light 2. Volcanic magna 3. lightning Panspermia: origin of life may have come from a meteorite or comet containing up to 80 A.A Main difference between living and non living is the bioinformational (DNA) passed on to offspring. Condition on early earth First organisms emerged around 3.8 BYA. Early atmosphere had CO2, N2, H2O, and H2. CO2 is used in Photosynthesis. We have N from microbial by bacteria and transformed into organic compounds. Reducing atmosphere ample availability of hydrogen atoms with their electrons, no Oxygen? Oxygen would stop the normal formation of organic molecules. Miller Urey Experiment page 505 506 , reducing gases: water, ammonia, methane and hydrogen excluding oxygen. Used electrodes to stimulate lightning Small organic molecules were generated in their apparatus. Evolution of cells RNA (ribozymes) May have been first genetic material. DNA is more stable than RNA Amino acids polymerized into proteins Metabolic pathway emerged Lipid bubbles became living cells with cell membranes First organism around 3.8 BYA Eukaryotic cells (around 1.5 BYA) Sexual reproduction Multicellularity RNA first molecule that carry bio information. Be familiar with the chart. The earth formed around 4.6 BYA. Classification of organisms More than 2000 years ago, Aristotle divided living things into animals and plants. Taxonomy is the science of classifying living things. A classification level is called a TAXON . Scientific names avoid the confusion caused by common names. The Linnean hierarchy Domain King Phylum class order family genus species. Taxonomist use a hierarchical system to classify organisms D o k ing p lay c hess o n f ine g rain s and Species: specific Know Page 509 Monophyletic know what it is? A monophyletic group consists of an ancestor and all its descendents. Paraphyletic does not include descendants, just the most reascent group. Limitations of the hierarchy Many hierarchies are being re examined based on the results of molecular analysis Linnaean taxonomy does not take into account evolutionary relationships Grouping organisms. Carls Woese proposed a six kingdom systems. Page 509 510 Domain archaea
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Domain bacteria Domain Eukarya includes protist, plantae, fungi, and amimalia. Giving a total of 6. Each of them forms a clade . Page 510 . Horizontal Gene transfer . Bacteria do it all the time they obtain DNA from the environment and transfer it horizontally. Bacteria Most abundant organisms of earth Extract nitrogen from the air, and recycle carbon and sulfur Perform much of the world's photosynthesis (from the oceans bacteria located 300 feet under the ocean, very little oxygen comes from trees) why do we need the forest then? We need it for air cleaning, moderate the climate. Responsible for many forms of disease, but also responsible for our life.
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This note was uploaded on 09/28/2009 for the course BIO 1620 taught by Professor Bybee during the Spring '06 term at Utah Valley University.

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biology 1620 notes - CHAPTER 26 8/26/09 Origins of life...

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