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Life on Earth

Life on Earth

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Life on Earth

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  1. Life on Earth Life on Earth

  2. Life on Earth as a 24 hour Analogy

  3. Life is the Product of EvolutionandEvolution is the Result of Reproduction

  4. Life is Based on Reproduction Each INDIVIDUAL ORGANISM is dualistic: • We are each a REPLICATOR • We are each an ecological INTERACTOR,the role of which is to command access to those environmental resources required to reproduce Because we reproduce, we are each MEMBERS OF LINEAGES

  5. What Evolves?Individuals or Lineages? Individuals can not evolve Individuals are transient …they don’t live long Individuals are genetically fixed …they can’t change genetically Lineages can and do evolve

  6. Evolution is change in genetic composition of lineages

  7. How is evolution based on reproduction? • Reproduction produces LINEAGES …successive generations sharing genetic continuity …potentially immortal • Reproductive fidelity is imperfect …mutations occur, producing GENETIC VARIATION …genetic novelties arise routinely. These represent genetic experiments • Reproduction has a multiplicative effect on population growth that results in NATURAL SELECTION …populations grow exponentially, but the resources they need do not. This results in a struggle for existence in which the individuals that are best suited to their environments tend to leave more offspring. Which causes the population to evolve (change in its genetic composition)

  8. Evolution has created biodiversity:

  9. The Origin of Life Where does life come from ?

  10. The Origin of LifeCosmology, Geology, then Biological Evolution Gravitational Collapse of Clouds of Matter: Formation of Galaxies, Solar Systems, and Planets The Age of Matter The Age of Energy B I G B A N G 13 by bp

  11. Nebulae - Clouds of Matter in Space

  12. A Galaxy

  13. Stars are born within nebulae

  14. Stars are born within nebulae

  15. Galaxy movie

  16. Why Did Life Originate on Earth? Temperature Gravity Large elements Atoms have an natural tendency to interact, forming molecules made of atoms bonded to one another

  17. Some stars return their ash into space explosion

  18. The Origin of LifeCosmology, Geology, then Biological Evolution Gravitational Collapse of Clouds of Matter: Formation of Galaxies, Solar Systems, and Planets A Hospitable Planet: Producing a variety of elements in a REDUCING ENVIRONMENT The Age of Matter Spontaneous formation of macromolecules and their polymers, including: proteins nucleic acids The Age of Energy B I G B A N G 13 My bp Replication L I F E: Evolving Lineages

  19. Reduction Reactions fewer bonds More bonds Oxidation Reactions Two Chemical Processes

  20. Chemical Processes Reduction Environments (early Earth): more bonds are made than broken, resulting in a net accumulation of molecules Oxidation Environments (since photosynthesis, because of O2): fewer bonds are made than broken, resulting in a net accumulation of molecules

  21. Reducing versus Oxydizing Environments Reduction characterized pre-photosynthesis Earth Life on Earth: Replicating Nucleic Acids reactive atoms small molecules macromolecules Oxidation minimal before photosynthesis

  22. Early EarthA Reducing Environment Reduction characterized pre-photosynthesis Earth reactive atoms small molecules Replicating Nucleic Acids macromolecules Oxidation minimal before photosynthesis

  23. Miller and Urey, 1953

  24. Earth’s Environment TodayAn Oxydizing Environment Reduction characterized pre-photosynthesis Earth reactive atoms small molecules Oxidation minimal before photosynthesis

  25. What kinds of molecules are formed? carbohydrates lipids proteins nucleic acids

  26. Spontaneous Formation of Proteins and RNA These subunits would have polymerized naturally, by geological processes alone Early Earth’s Reducing Environment produced pools of nucleotides and amino acids by geological processes (pre-biotic evolution) Proteins RNA amino acids RNA nucleotides

  27. RNA Replication First Life

  28. Nucleic Acids Can Reproduce

  29. The Transition to Prokaryotes

  30. Then and Now Reproduction Info storage catalysis RNA replicators Reproduction Info storage catalysis DNA RNA Proteins middle man

  31. First Life to Modern Cells First Life: RNA organisms No RNA RNA Modern Life Yes DNA Proteins Cellular? Hereditary Molecule? Primary Catalytic Molecule?

  32. Review Capabilities: DNA, RNA, and Proteins

  33. Complex 3D Shapesand Catalysis double stranded simple 3D shape single stranded complex 3D shape single stranded complex 3D shape

  34. The Central Dogma of Biologystrandedness and functional versatility reproduction primary structure (info storage) no catalysis double stranded simple 3D shape reproduction primary structure (info storage) catalysis single stranded complex 3D shape no reproduction primary structure catalysis single stranded complex 3D shape

  35. Heredity and Catalysis Replication Catalysis √ DNA RNA Proteins √ √ √

  36. Why Did Cellular Compartmentalization Evolve?

  37. Why Did Cellular Compartmentalization Evolve?

  38. Probable StepsAfter Cellularity

  39. First: RNA Replication

  40. The First Genes replication produced progeny molecules …complete copies of parent molecule ribozyme is partial copy of parent molecule …coding region of parent is a gene. ribozyme is partial copy of parent molecule …coding region of parent is a gene.

  41. Protein Synthesis replication produced progeny molecules ribozyme (e.g., rRNA) ribozyme mRNA tRNA

  42. Why Did Protein Replace RNA in Catalysis? • Complex structure is the hallmark of a catalyst • Protein’s molecular alphabet is larger (20 amino acids versus 4 nucleotides • Amino acids are more chemically diverse than nucleotides • Having a greater number or more diverse building blocks allows proteins to have more complex structure than RNA molecules

  43. Why Did DNA Replace RNA in Heredity?

  44. DNA and RNA Polymerasesproofreading requires a previous nucleotide A G C T A A A U U A G C T A A A T T RNA polymerase DNA Polymerase elongation elongation proof-reading

  45. DNA Proof-reading A G C T A A G T T A G C T A A T T A G C T A A A T T A G C T A A G A T T A G G Proof-reading requires the presence of a previous nucleotide before a new one can be added …RNA polymerase has no such requirement (primase either)

  46. DNA Repair The double strandedness of DNA enables: • recognition of mutation sites • replacement of excised nucleotides with complementary nucleotides

  47. Why Did DNA Replace RNA in Heredity? DNA has a much lower mutation rate than RNA