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Summer 2006 Workshop in Biology and Multimedia for High School Teachers How Did Life Originate? By Kerri Coleman North Attleboro High School The Origin Of The Earth ~4.6 Billion years the earth was formed ~3.2 Billion years ago the introduction of Blue-green cyanobacteria Oxygen is produced Free oxygen begins to accumulate Ozone is synthesized Aerobic metabolism can begin http://www-cyanosite.bio.purdue.edu/images/lgimages/bloom4.jpg Image courtesy of Federico Emiliani (Universidad Nacional del Litoral), Mark Schneegurt (Wichita State University), and Cyanosite (www-cyanosite.bio.purdue.edu) How Did Life Originate? Spontaneous Chemical Generation Synthesis “Primordial Soup” Panspermia Spontaneous Generation Organisms arose spontaneously from non-living matter • Example: Maggots arose from rotting meat Disproved in 1668 by Francesco Redi, an Italian physician • Used 3 samples of rotting flesh placed in flasks open to air sealed covered with gauze • Maggots were generated in the open container, where flies had access to meat and were able to lay their eggs Results of experiment were not conclusive enough for some people Louis Pasteur -1864 Experiment showed that life did not spontaneously appeared • Meat broth was boiled in a flask to kill microorganisms • The neck of the flask was heated and bent into the shape of an S • Microorganisms could not get into broth because they would settle in S shaped neck before contact with broth • No growth was in discovered in the broth • Broth was tilted into the S component and microorganisms contaminated broth and grew http://en.wikipedia.org/wiki/Image:Charles_Darwin_1881.jpg#file “Some warm pond with all sorts of Ammonia, phosphoric salts, Heat, light, electricity etc…..” -Charles Darwin, on the origins of life in tidal pools Chemical Synthesis- “Primordial Soup” Dr. Stanley Miller and Dr. Harold Urey-1953 ammonia (NH3) methane (CH4) water (H2O) hydrogen (H2) electricity in an elaborate flask apparatus • Electricity was passed through the apparatus • Amino Acids and hydrocarbons were synthesized http://en.wikipedia.org/wiki/Image:Miller-Urey_experiment_en.png#file The Formation of Glycine Glycine most abundant amino acids synthesized in Urey / Miller experiment Synthesis occurs in 2 steps CH2O + NH3+ HCN NH2CH2CN + H2O CH2O = formaldehyde NH3 = ammonia HCN = hydrogen cyanide NH2CH2CN= ammonitrile H2O = water NH2CH2CN + 2H2O NH2CH2COOH + NH3 NH2CH2COOH = glycine Panspermia- “seeds everywhere” Life came from space on comets • Hydrocarbons, amino acids, water(s) and bacteria September 28, 1969 Murchison, Australia • Meteorite shower fell Analysis determined it was carbon rich • Organic compounds • Many of the protein Amino Acids found in biological systems http://meteorites.asu.edu/images/education/allende-big.jpg Image provided by NASA JPL Which Theory Do You Think Is Correct? Discuss within each group The pros and cons to each theory • Make sure to use reliable sources on the web and cite all pages What evidence is there to support or disclaim a theory • For example: Fossil records Could there be another theory? Sites To Check Out http://www.panspermia.org/intro.htm http://www.accessexcellence.org/WN/NM/miller.html http://www.accessexcellence.org/WN/SUA02/primordial_soup.html http://www.chem.duke.edu/~jds/cruise_chem/Exobiology/amino.html http://meteorites.asu.edu/images/education/allende-big.jpg