Early Earth and the Origin of Life

2. Early Earth and the Origin of Life We will concentrate in this lecture on two things: • An overview of the logic of the origin of life • What is the history of life’s origins? • How is it possible that life could form? • Why doesn’t life arise de novo today? • An overview of the diversity of life • Problems with the the Five-Kingdom system • Attempts at dealing with these problems via an n-Kingdom system of organismal classification • Carl Woese and the Universal tree

3. Origin of Life (overview) • Singularity: Pre-Big Bang • Inflation: Energization of Big Bang • Universal expansion: Energy provided by Inflation • Sub-atomic particles: Energy  Mass conversion as universe cooled • Atoms: mostly Hydrogen • Gas-cloud inhomogeneities: provided gravity wells • Stars: gas-cloud gravitational collapse • Super novae: forgers & disseminators of “metals” Metals: Atoms other than H and He • Molecules: More complex than H2 • Accretion: Formation of planets • Planets: gravity wells (like stars but smaller)

4. Synthesis of Lighter Elements

5. Molecules in Space

6. Rest of Elements from Super Novae

7. Super Nova Up Close (Hubble)

8. Product of Homogeneous Accretion?

9. Or of Inhomogeneous Accretion?

10. Planets: solid substrate upon which life can evolve • Chemical evolution: Formation of more-complex chemicals, in space or on planets • Replicators: Chemicals capable of templating their own replicaiton • Separate phenotype: Molecules responsible for some phenotype are other than those carrying genotype • Individuality: Protocells then cells • Prokaryotes: Earliest true cells (~3.5 bya) • Endomembrane system: Increase in cellular mophology  eukaryotes • Endosymbiosis: Further increase in eukaryote complex and expansion of biochemistry • Multicellularity: Cooperative grouping of differentiated cells • Etc.: Plants, Fungi, Animals Origin of Life (overview)

11. Large Volumes Quantitatively lots of (large numbers of) Experiments • Diverse Environment Qualitatively lots of (high diversity of) Experiments • Lots of Time Perhaps hundreds of millions of years • diverse, numerous experiments plus potential for experiments to build upon each other (evolution) • Reducing Atmosphere Without lots of O2 around, organic molecules are much more stable • this was the case before modern photosynthetic organisms evolved (i.e., cyanobacteria) • Organic Molecules Presence of complex organic molecules can be inferred but also can be addressed experimentally (e.g., Miller-Urey Exp.) Logic of Origin of Life

12. Geological Time

13. Energy Volcanoes, Deep-Sea Vents, Lightning, Sun Light (including lots of UV pre-ozone layer since ozone from free O2), Chemicals from Space • Logic of Self Replication & Natural Selection • Stuff that is durable and easily made tends to accumulate • Chemicals that are stable and can duplicate themselves naturally increase in abundance • Someday we will even understand the chemistry • No Competition • Unlike today, there were no super-sophisticated modern organisms to compete with (i.e., no bacteria) • In the Land of the Blind the One-Eyed Chemical is King! Logic of Origin of Life

15. Geological Time

16. Reducing Atmosphere

17. Miller & Urey Experiment (1953) Amino Acids, etc.

18. Terrestrial Energy Sources

19. Very Hot Early Earth

20. Chemical Evolution: RNA

21. Protocells (Individuality, sort of)

22. Chem. Evol. through True Cells additional time Universal Ancestor Chemical Evolution

23. Early-Cells Evidence: Cyanobacteria 3.5 billion years old Modern Leptolyngbya

24. Early-Cells Evidence: Stromatolites Stromatolites are still formed today at a few places like Shark Bay in Australia

25. Fossil Stromatolites

26. Classifying Life – 5 Kingdoms Note bias towards large things

27. 5 Kingdom System

28. 16S rRNA Three Cellular Domains

29. “n”-Kingdoms System(s) Universal Ancestor (DNA, codons, RNA, proteins, etc.)

30. Relatedness ofAll Cellular Organisms

31. Link to Next Presentation

32. Acknowledgements http://207.233.

33. Kingdom Plantae

34. Kingdom Fungi

35. Kingdom Animalia

36. Kingdom Protista

37. DOMAIN BACTERIA DOMAIN ARCHAEA DOMAIN EUKARYA Gram-positive bacteria Green sulfur bacteria Methanobacterium Methanococcus Thermococcus Archaeoglobus Thermoproteus Dinoflagellates Purple bacteria Methanopyrus Cyanobacteria Flavobacteria Trypanosoma Brown algae Entamoebae Slime molds Green algae Pyrodictium Thermotoga Halococcus Sulfolobus Red algae Animals Thermus Euglena Diatoms Ciliates Aquifex Giardia Plants Fungi pSL17 pJP27 pJP78 pSL12 Stromatolites (mounds of photosynthetic bacteria) Kingdom Monera

38. Protista  Eukaryotes

39. “13”-Kingdom System + Bacteria + Archaea