The document summarizes key ideas and evidence regarding the origin of life on Earth, including: 1) Early Earth conditions like the Urey atmosphere could have enabled the abiotic synthesis of organic molecules and compounds found in meteorites. 2) Experiments in the 1950s and 1960s demonstrated plausible prebiotic synthesis routes for important biomolecules like amino acids and nucleotides. 3) RNA molecules could have served both genetic and catalytic functions in a hypothetical "RNA world" before the emergence of DNA and proteins.

1. La cosecha del ‘53: cincuenta años del experimento de Miller Antonio Lazcano Araujo Facultad de Ciencias, UNAM E-mail: alar@correo.unam.mx

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

11. A heterotrophic origin of life? reducing atmosphere primitive soup synthesis of organic compounds primordial heterotrophs

12. 1) Proust 1807 HCN polymer + adenine (?) 2) Wöhler 1828 NH 4 NCO urea 3) Strecker 1850 HCH 3 CHO + NH 3 + HCN alanine 4) Butlerow 1861 HCHO sugars OH- OH- Early abiotic synthesis of biochemical monomers

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

18. aromatic hydrocarbons alcohols (C 1 -C 4 ) aliphatic hydrocarbons aldehydes (C 2 -C 4 ) sulfonic acids polyols (C 2 -C 4 ) phosphonic acids monocarboxylic acids (C 1 -C 8 ) ketones (C 3 -C 5 ) dicarboxylic acids (C 2 -C 5 ) hydroxy acids (C 2 -C 9 ) amines (C 1 -C 4 ) amino acids pyridines urea quinolines purines polypyrroles pyrimidines Compounds in the Murchison meteorite

21. permafrost pore water HCN, RCHO NH 3 , CH2=CH-CN heat source

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

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

33. Meteor Crater, Arizona

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

38. Have too many cooks spoiled the soup?

39. extraterrestrial organics pyrite primordial soup CH 4 NH 3 HCN

40. extraterrestrial organics

41. organics from space Bada & Lazcano (2002) Science 296 : 1982

42. *A A A *U *A *U *U *U U U *A *A montmorillonite Ferris 2002

43. activated derivatives and common minerals may have led to the synthesis of prebiotic genetic polymers

44. Base pairing is for free

45. What was the nature of the backbone?

46. Mendeleyev and the abiotic origin of oil Fe 3 C + H 2 O hydrocarbons

47. alkenes acid conditions alcohols Fe 3 C + H 2 O alkanes + alkenes 1) 2) From hydrocarbons to amphiphilic compounds

48. hydrophobic hydrophilic

53. DNA DNA RNA protein

54. RNA is a nucleic acid with a RIBOSE-PHOSPHATE backbone WHAT’S IN A NAME?

55. WHAT’S IN A NAME? RNA is a nucleic acid with a RIB OSE-PHOSPHATE backbone -ose is for sugars and R ockefeller I nstitute of B iochemistry

56. Store genetic information (like DNA) Catalize chemical reactions (like proteins) RNA molecules:

58. Butlerov´s formose reaction H 2 CO sugars OH -

59. Decker et al (1982)

60. Sugars are unstable organic compounds sugar half-life (min) ribose 73 2-deoxyribose 225 ribose-5-phosphate 7 ribose-2,4-biphosphate 31

62. - store genetic information - replicate other RNAs - activate amino acids - bind themselves to amino acids - catalyze peptide-bond formation RNA molecules can

63. Moore & Steitz (2002)

64. Cells with DNA, RNA & proteins RNA & protein biosynthesis RNA world ?

65. Archaea Eucarya Bacteria

66. LATIN Catalonian Spanish Romanian French Proven çal Italian ancient..... but clearly not primitive

67. Mycoplasma genitalium TIGR Microbial Database

68. Figure 1 . Prokaryotic genome size distribution (N=641)

69. RNA World Primitive soup ? RNA - protein DNA, RNA, protein Archaea Eucarya Bacteria