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La cosecha del ‘53: cincuenta años del experimento de Miller     Antonio Lazcano Araujo Facultad de Ciencias, UNAM E-mail:...
 
 
 
Rasmussen (2000)  Nature   405 :677 Walsh & Lowe (1985)  Nature   314 :530 TRACES OF ARCHEAN LIFE (?) Schopf  (1993)  Scie...
  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 impa...
Understanding the origin of life is hindered by the lack of   1. geological evidence of the prebiotic environment   2. fos...
The origin of life was a) autotrophic capable of synthesizing its own components from CO 2 b) heterotrophic formed from a ...
A pyrite-mediated origin of life?  CO 2 H 2 S Organic compounds Metabolic networks  Autotrophic  organism Wächtershäuser (...
 
A heterotrophic origin of life? reducing atmosphere  primitive soup synthesis of organic compounds primordial heterotrophs
  1)  Proust  1807   HCN   polymer + adenine (?)   2)  Wöhler  1828   NH 4 NCO  urea    3)  Strecker  1850   HCH 3 CHO + N...
 
 
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+,  ...
 
 
aromatic hydrocarbons alcohols (C 1 -C 4 ) aliphatic hydrocarbons aldehydes (C 2 -C 4 ) sulfonic acids polyols (C 2 -C 4 )...
 
 
permafrost pore water HCN, RCHO NH 3 , CH2=CH-CN heat source
 
 
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   -> ...
 
 
 
 
 
1. Amino acids from Strecker synthesis   2. Purines from HCN polymerization   3. Pyrimidines from cyanoacetylene & urea   ...
1953: Annus mirabilis Watson & Crick Double-helix model of DNA Sanger & Thompson   Complete sequencing of a protein S.L.Mi...
  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 ...
Meteor Crater, Arizona
 
 
Pyrite-mediated organic synthesis and several other reactions   1)  2CH 3 -SH + CO NiS/FeS CH 3 CO(SCH 3 ) + H 2 S   2)  C...
  reducing atmosphere  produces the right  prebiotic relevance denied stuff by many --but not all   input in meteorites mu...
Have too many cooks spoiled the soup?
extraterrestrial organics pyrite primordial soup CH 4 NH 3 HCN
extraterrestrial organics
organics from space Bada & Lazcano (2002)  Science   296 : 1982
*A A A *U *A *U *U *U U U *A *A montmorillonite Ferris 2002
  activated derivatives and common minerals may have led to the synthesis of prebiotic genetic polymers
Base pairing is for free
What was the nature of the backbone?
Mendeleyev and the abiotic origin of oil  Fe 3 C + H 2 O hydrocarbons
alkenes acid conditions  alcohols Fe 3 C + H 2 O alkanes + alkenes 1) 2) From hydrocarbons  to amphiphilic compounds
hydrophobic hydrophilic
 
<ul><li>many different catalytic agents </li></ul><ul><li>polymers with sequences of nucleobases </li></ul><ul><li>membran...
 
 
DNA DNA RNA protein
RNA is a nucleic acid with a RIBOSE-PHOSPHATE backbone WHAT’S IN A NAME?
WHAT’S IN A NAME?   RNA is a nucleic acid with a  RIB OSE-PHOSPHATE  backbone     -ose is for sugars and    R ockefeller  ...
Store genetic information  (like DNA) Catalize chemical reactions (like proteins) RNA molecules:
 
Butlerov´s formose reaction H 2 CO sugars OH -
Decker  et al   (1982)
Sugars are unstable organic compounds      sugar half-life      (min)   ribose   73 2-deoxyribose   225 ribose-5-phosphate...
 
  - store genetic information   - replicate other RNAs - activate amino acids - bind themselves to amino acids    - cataly...
Moore & Steitz (2002)
Cells with DNA, RNA & proteins RNA & protein biosynthesis RNA world ?
Archaea Eucarya Bacteria
LATIN Catalonian Spanish Romanian French Proven çal Italian ancient..... but clearly not primitive
Mycoplasma genitalium TIGR Microbial Database
Figure 1 . Prokaryotic genome size distribution (N=641)
RNA World Primitive soup ? RNA - protein DNA, RNA, protein Archaea Eucarya Bacteria
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Platica ToñO Lazcano

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  1. 1. La cosecha del ‘53: cincuenta años del experimento de Miller     Antonio Lazcano Araujo Facultad de Ciencias, UNAM E-mail: alar@correo.unam.mx  
  2. 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
  3. 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)
  4. 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
  5. 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)
  6. 9. A pyrite-mediated origin of life? CO 2 H 2 S Organic compounds Metabolic networks Autotrophic organism Wächtershäuser (1988) pyrite (FeS 2 ) FeS
  7. 11. A heterotrophic origin of life? reducing atmosphere primitive soup synthesis of organic compounds primordial heterotrophs
  8. 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
  9. 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
  10. 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
  11. 21. permafrost pore water HCN, RCHO NH 3 , CH2=CH-CN heat source
  12. 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
  13. 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
  14. 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
  15. 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
  16. 33. Meteor Crater, Arizona
  17. 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
  18. 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  
  19. 38. Have too many cooks spoiled the soup?
  20. 39. extraterrestrial organics pyrite primordial soup CH 4 NH 3 HCN
  21. 40. extraterrestrial organics
  22. 41. organics from space Bada & Lazcano (2002) Science 296 : 1982
  23. 42. *A A A *U *A *U *U *U U U *A *A montmorillonite Ferris 2002
  24. 43.   activated derivatives and common minerals may have led to the synthesis of prebiotic genetic polymers
  25. 44. Base pairing is for free
  26. 45. What was the nature of the backbone?
  27. 46. Mendeleyev and the abiotic origin of oil Fe 3 C + H 2 O hydrocarbons
  28. 47. alkenes acid conditions alcohols Fe 3 C + H 2 O alkanes + alkenes 1) 2) From hydrocarbons to amphiphilic compounds
  29. 48. hydrophobic hydrophilic
  30. 50. <ul><li>many different catalytic agents </li></ul><ul><li>polymers with sequences of nucleobases </li></ul><ul><li>membrane-forming compounds </li></ul>The evidence suggests that before the origin of life there were already
  31. 53. DNA DNA RNA protein
  32. 54. RNA is a nucleic acid with a RIBOSE-PHOSPHATE backbone WHAT’S IN A NAME?
  33. 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
  34. 56. Store genetic information (like DNA) Catalize chemical reactions (like proteins) RNA molecules:
  35. 58. Butlerov´s formose reaction H 2 CO sugars OH -
  36. 59. Decker et al (1982)
  37. 60. Sugars are unstable organic compounds     sugar half-life (min)   ribose 73 2-deoxyribose 225 ribose-5-phosphate 7 ribose-2,4-biphosphate 31
  38. 62. - store genetic information   - replicate other RNAs - activate amino acids - bind themselves to amino acids    - catalyze peptide-bond formation RNA molecules can
  39. 63. Moore & Steitz (2002)
  40. 64. Cells with DNA, RNA & proteins RNA & protein biosynthesis RNA world ?
  41. 65. Archaea Eucarya Bacteria
  42. 66. LATIN Catalonian Spanish Romanian French Proven çal Italian ancient..... but clearly not primitive
  43. 67. Mycoplasma genitalium TIGR Microbial Database
  44. 68. Figure 1 . Prokaryotic genome size distribution (N=641)
  45. 69. RNA World Primitive soup ? RNA - protein DNA, RNA, protein Archaea Eucarya Bacteria
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