Origin of Life

1. Origin of Life Origin of Universe Origin of Elements Origin of Sun & Solar System Origin of Living Systems Evolution of Living Systems

2. Arguments for Origin • Divine • Extraterrestrial • Chemical evolution

3. In the beginning…a big bang • About 15 billion years ago • Evidence • Hubble Expansion • Big Bang Nucleosynthesis • Microwave background radiation

4. Big bang – Hubble Expansion • Galaxies appear to be moving away from our galaxy • Initially observed by Edward Hubble in 1927 • Galaxies have a red shift in light produced by the Doppler effect similar to sound (also used in radar) • The movement of galaxies away from us corresponds to an equation called "Hubble's Law" • The time elements in Hubble's Law permit the estimation of the age of the universe – about 13 billion years (+ or – a few billion)

5. Big Bang - Nucleosynthesis • Occurred during seconds 100 to 300 following big bang • Result of temperature of universe dropping below that required for nuclear fusion (4 H to He) • Produced a large amount of Helium which is very stable and cannot be converted easily into heavier elements • Amount of Helium measured in universe is consistent with Big Bang Nucleosynthesis

6. Big Bang – Background Radiation • The cosmic microwave background was predicted in 1948 • 1964-65Arno Penzias and Robert Woodrow Wilson measured the temperature to be approximately 3 K. Robert Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson interpret this radiation as a signature of the big bang. • Penzias and Wilson received the 1978 Nobel Prize in Physics for their discovery. • Existence of this radiation inconsistent with steady state model that Eistein and others favored.

7. Origin of Elements Hydrogen fuses to form helium Hydrogen & Helium most abundant Sun’s energy drives life processes Stars become red giants as hydrogen runs low (about 10 billion years) Helium fuses into other elements Star goes nova (blows up) Heavier elements released into space

9. Sun and Planets • Sun formed about 5 billion years ago • Gravitational attraction of gases • Gravitational field becomes great enough to initiate fusion reactions • Accretion forms inner planets & moons • Process occurs quickly-earth & moon about same age

11. Early Earth • Earth 4.6 billion years old (U238 dating) • Moon rocks & meteorites • Early Atmosphere mostly non-oxidizing • Nitrogen • Carbon dioxide • Water (as water vapor) • Lesser amounts • CO, H2, NH3, H2S and CH4

12. Venus, Earth & Mars Comparison *870º F **70º F *** -30º F

13. Characteristics of Life • Composed of Cells • Reproduce in kind • Metabolism / Energy Transformations • Respond to stimuli

14. Abiogenesis • The process of life from the inanimate • Formation of organic monomers from inorganic molecules • Formation of organic polymers from organic monomers • Evolution of membranes • Evolution of DNA based reproduction

15. Chemical Evolution • Requires a non-oxidizing atmosphere • No oxygen initially • Requires a source of energy • Lightening, UV light, Volcanoes & Meteorites • Requires hydrogen, nitrogen, carbon, oxygen • Components of organic and biological compounds • water, ammonia, carbon dioxide/methane • Requires time

16. Molecular Clues to Origins • The following suggest common origin: • Organisms use molecules based mostly on hydrogen, nitrogen and carbon present on early earth • Only L-amino acids found in proteins • DNA & RNA are universal in all organisms • ATP is energy intermediate in all organisms • All organisms initiate carbohydrate metabolism with similar steps • Genetic code is universal • All cells bound by a plasma membrane composed of a lipid bylayer

17. Organic Monomers • Oparin & Haldane suggest organic molecules could form from precursors (1930) • Miller & Urey test using an apparatus which simulates early earth (~1950) Stanley Miller

19. Organic Polymers • Major Groups - Nucleic acid, proteins, lipids, polysaccharides - have been formed synthetically • Information vs. Structural vs. Catalytic • Protenoids will form spontaneously on clay • D & L amino acids can be selected on calcite - a common crystalline mineral • RNA - has all three capabilities

20. RNA “Life” • Ribose, a component of RNA will form spontaneously from formaldehyde and HCN • Some RNA’s have been found to have catalytic activity - ribozymes • RNA has structural capability in ribosomes • RNA’s have an information carrying capacity in viruses & RNA’s have been induced to take on new traits

21. RNA Life • Article by Leslie Orgel • http://www.geocities.com/capecanaveral/lab/2948/orgel.html

22. DNA Life • Separation of functional roles of molecules related to constant input of energy • Separation of information carrying capacity from other roles of molecules in cells • RNA to DNA • RNA to Protein - catalytic capacity • Protein & polysacharides take on structural roles in cells

23. Membranes • Why cells? • Inside vs. outside • Concentration effect on reactions • Indications of process • Microspheres - hydrocarbons in water form microsperes which can contain other molecules • Liposomes - artificial lipid bilayers very similar to cell membranes but smaller - used for drug transport

24. Prokaryotic Cells • Appear about 3.5 billion years ago • Photosynthesis in blue-green algae begins to modify atmosphere • Oxygen in atmosphere begins to modify types of organisms

28. Eukaryotic Cells • Begin to appear in fossil record about 2.5 billion years ago • Considerable internal structure relative to prokaryotic cells • Precursors to multicellular organisms

29. Fossil Record • Dating • Stratographic analysis • Radiometric dating • Geologic Time • Precambrian - 4.6 to 0.57 billion years ago • Fossils all unicellular • Caambrian – 0.57 billion years ago to present • Multicellular organisms • Extinction Level Events

31. Evidence for Evolution • Physical methods – radiometric dating • Fossil record • Anatomical comparisons • DNA sequence analysis • Laboratory experiments showing selection