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 Oxygen is produced Free oxygen begins to accumulate Free oxygen begins to accumulate Ozone is synthesized Ozone is synthesized Aerobic metabolism can begin Aerobic metabolism can begin 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 Generation  Chemical Synthesis “Primordial Soup”  Panspermia

 Spontaneous Generation Organisms arose spontaneously from Organisms arose spontaneously from non-living matter Example: Maggots arose from rotting meatExample: Maggots arose from rotting meat Disproved in 1668 by Francesco Redi, an Italian physician Disproved in 1668 by Francesco Redi, an Italian physician Used 3 samples of rotting flesh placed in flasksUsed 3 samples of rotting flesh placed in flasks open to air open to air sealed sealed covered with gauze covered with gauze Maggots were generated in the open container, where flies had access to meat and were able to lay their eggsMaggots 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 Results of experiment were not conclusive enough for some people

 Louis Pasteur Experiment showed that life did not spontaneously appeared Experiment showed that life did not spontaneously appeared Meat broth was boiled in a flask to kill microorganismsMeat broth was boiled in a flask to kill microorganisms The neck of the flask was heated and bent into the shape of an SThe 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 brothMicroorganisms could not get into broth because they would settle in S shaped neck before contact with broth No growth was in discovered in the brothNo growth was in discovered in the broth Broth was tilted into the S component and microorganisms contaminated broth and grewBroth was tilted into the S component and microorganisms contaminated broth and grew

“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 Dr. Stanley Miller and Dr. Harold Urey-1953 ammonia (NH 3 ) ammonia (NH 3 ) methane (CH 4 ) methane (CH 4 ) water (H 2 O) water (H 2 O) hydrogen (H 2 ) hydrogen (H 2 ) electricity in an elaborate flask apparatus electricity in an elaborate flask apparatus Electricity was passed through the apparatusElectricity was passed through the apparatus Amino Acids and hydrocarbons were synthesizedAmino Acids and hydrocarbons were synthesized

The Formation of Glycine  Glycine most abundant amino acids synthesized in Urey / Miller experiment Synthesis occurs in 2 steps Synthesis occurs in 2 steps CH 2 O + NH 3 + HCN  NH 2 CH 2 CN + H 2 O CH 2 O + NH 3 + HCN  NH 2 CH 2 CN + H 2 O CH 2 O = formaldehyde CH 2 O = formaldehyde NH 3 = ammonia NH 3 = ammonia HCN = hydrogen cyanide HCN = hydrogen cyanide NH 2 CH 2 CN= ammonitrile NH 2 CH 2 CN= ammonitrile H 2 O = water H 2 O = water NH 2 CH 2 CN + 2H 2 O  NH 2 CH 2 COOH + NH 3 NH 2 CH 2 CN + 2H 2 O  NH 2 CH 2 COOH + NH 3 NH 2 CH 2 COOH = glycine NH 2 CH 2 COOH = glycine

 Panspermia- “seeds everywhere” Life came from space on comets Life came from space on comets Hydrocarbons, amino acids, water (s) and bacteriaHydrocarbons, amino acids, water (s) and bacteria September 28, 1969 Murchison, Australia September 28, 1969 Murchison, Australia Meteorite shower fellMeteorite shower fell Analysis determined it was carbon rich Analysis determined it was carbon rich Organic compoundsOrganic compounds Many of the protein Amino Acids found in biological systemsMany of the protein Amino Acids found in biological systems Image provided by NASA JPL

Which Theory Do You Think Is Correct?  Discuss within each group The pros and cons to each theory The pros and cons to each theory Make sure to use reliable sources on the web and cite all pagesMake sure to use reliable sources on the web and cite all pages What evidence is there to support or disclaim a theory What evidence is there to support or disclaim a theory For example: Fossil recordsFor example: Fossil records  Could there be another theory?

Sites To Check Out     