Early Earth and the Origin of Life (PowerPoint)

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					Early Earth and the Origin of Life
We will concentrate in this lecture on two things:
   1. 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?
   2. 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
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)
Synthesis of Lighter Elements
Molecules in Space
Rest of Elements from Super Novae
Super Nova Up Close (Hubble)
Product of Homogeneous Accretion?
Or of Inhomogeneous Accretion?
                             Planets: solid substrate upon which life can evolve
Origin of Life (overview)    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
Logic of Origin of Life    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.)
Geological Time
                           Energy  Volcanoes, Deep-Sea Vents, Lightning,
Logic of Origin of Life     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!
Geological Time
Reducing Atmosphere
Miller & Urey Experiment (1953)
Terrestrial Energy Sources
Very Hot Early Earth
Chemical Evolution: RNA
Protocells (Individuality, sort of)
Chem. Evol. through True Cells

                         time
                      additional
Early-Cells Evidence: Cyanobacteria




   3.5 billion years old   Modern Leptolyngbya
Early-Cells Evidence: Stromatolites




  Stromatolites are still formed today at a
   few places like Shark Bay in Australia
Fossil Stromatolites
Classifying Life – 5 Kingdoms




        towards
       Note bias

      large things
5 Kingdom System
Three Cellular Domains   16S rRNA
“n”-Kingdoms System(s)




                         Universal Ancestor (DNA, codons, RNA, proteins, etc.)
    Relatedness of
All Cellular Organisms
Link to Next Presentation
Acknowledgements



       http://207.233.
Kingdom Plantae
Kingdom Fungi
Kingdom Animalia
Kingdom Protista
                                                    Kingdom Monera

                                                            Aquifex
                                                            Thermus
                                                            Thermotoga
                                                            Gram-positive bacteria
                                                            Green sulfur bacteria
                                                            Purple bacteria
                                                            Cyanobacteria
                                                                                 DOMAIN BACTERIA




                                                            Flavobacteria
                                                            pJP78
                                                            pJP27
                                                            pSL17
                                                            pSL12
                                                            Pyrodictium
                                                            Sulfolobus
                                                            Thermoproteus
                                                            Methanopyrus
                                                            Methanobacterium
                                                            Thermococcus
                                                            Methanococcus
                                                            Archaeoglobus
                                                                                 DOMAIN ARCHAEA




                                                            Halococcus
                                                            Giardia
                                                            Trypanosoma
                                                            Euglena
                                                            Entamoebae
                                                            Slime molds
                                                            Dinoflagellates
                                                            Ciliates
                                                            Diatoms
                                                            Brown algae
                                                            Red algae
                                                            Green algae
                                                                                 DOMAIN EUKARYA




                                                            Plants
                                                             Fungi
                                                             Animals
Stromatolites (mounds of photosynthetic bacteria)
Protista  Eukaryotes
“13”-Kingdom System



                      + Bacteria
                      + Archaea

				
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posted:1/18/2012
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