1. La cosecha del ‘53: cincuenta años del experimento de Miller Antonio Lazcano Araujo Facultad de Ciencias, UNAM E-mail: alar@correo.unam.mx
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5. Rasmussen (2000) Nature 405 :677 Walsh & Lowe (1985) Nature 314 :530 TRACES OF ARCHEAN LIFE (?) Schopf (1993) Science 260 :530 Westfall et al (2001) Precamb Res 106 :93
6. Closing in on a time frame for the origin of life on the Earth 3.5 4.0 4.5 3.0 fossil record cooling of the Earth impact frustrations The age of the Earth (billion of years ago)
7. Understanding the origin of life is hindered by the lack of 1. geological evidence of the prebiotic environment 2. fossil record of prebiological system; and 3. an all-embracing, generally agreed definition of life
8. The origin of life was a) autotrophic capable of synthesizing its own components from CO 2 b) heterotrophic formed from a primitive soup c) extraterrestrial came from outer space (panspermia)
9. A pyrite-mediated origin of life? CO 2 H 2 S Organic compounds Metabolic networks Autotrophic organism Wächtershäuser (1988) pyrite (FeS 2 ) FeS
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11. A heterotrophic origin of life? reducing atmosphere primitive soup synthesis of organic compounds primordial heterotrophs
15. Some interstellar molecules H 2 , OH, SiS, HCl, NaCl, KCl, CH, CH+, CN, CO, CS, C 2 H 2 O, H 2 S, N 2 H+, SO 2 , HCO+, HCN, C 2 H, C 3 , C 2 O, COS NH 3 , H 2 CO, HNCO, H 2 CS, C 2 H 2 SiH 4 , HC 3 N, H 2 CN, CH 4 , C 5 , H 2 C=C=O, HCOOH, HNCO CH 3 OH, CH 3 CCN, HCONH 2 CH 3 COH, CH 3 C 2 H, CH 3 NH 2 , H 2 CCHCN, HC 5 N HCOOCH 3 , CH 3 CH 2 , (CH 3 ) 2 O, HCN 7 N HC 9 N, HC 11 N
24. C + 2H 2 -> CH 4 N 2 + 3H 2 -> NH 3 O 2 + 2H 2 -> H 2 O S + H 2 -> H 2 S CO 2 + 6H 2 -> CH 4 + 2H 2 O The Urey atmosphere
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30. 1. Amino acids from Strecker synthesis 2. Purines from HCN polymerization 3. Pyrimidines from cyanoacetylene & urea 4. Sugars from HCHO polymerization Prebiotic syntheses that work
31. 1953: Annus mirabilis Watson & Crick Double-helix model of DNA Sanger & Thompson Complete sequencing of a protein S.L.Miller Prebiotic synthesis of organic compounds
32. Types of planetary atmospheres Reducing : CH 4 , NH 3 , N 2 , H 2 O, H 2 CO 2 , N 2 , H 2 O, H 2 CO 2 , H 2 , H 2 O Neutral: CO 2 , N 2 , H 2 O Oxidizing : CO 2 , N 2 , H 2 O, O 2
36. Pyrite-mediated organic synthesis and several other reactions 1) 2CH 3 -SH + CO NiS/FeS CH 3 CO(SCH 3 ) + H 2 S 2) CH 3 -SH + CO + H 2 O NiS/FeS CH 3 -COOH + H 2 S 3) amino acids + CO NiS/FeS dipeptides
37. reducing atmosphere produces the right prebiotic relevance denied stuff by many --but not all input in meteorites must have occurred survival & availability of input doubtful high-temperature must have occurred suite of organic products vent chemistry restricted so far source advantages disadvantages Prebiotic Synthesis