Origin of Life Origin of Universe Origin of

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

Arguments for Origin • Divine • Extraterrestrial • Chemical evolution

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

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. 7 billion years

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

Big Bang – Background Radiation • If big bang then there should exist remanentt heat • The cosmic microwave background was predicted in 1948 • 1964 -65 Arno Penzias and Robert Woodrow Wilson measured the temperature to be approximately 2. 725 K which translates to specific background radiation in the microwave range. • This radiation as a signature of the big bang. • Penzias and Wilson received the 1978 Nobel Prize in Physics for their discovery. • Observation confirmed by later NASA observations.

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

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 from dust and debris of supernova • Process occurs quickly-earth & moon about same age

Early Earth • Earth 4. 6 billion years old (U 238 dating) – Moon rocks & meteorites • Early Atmosphere mostly non-oxidizing – Nitrogen – Carbon dioxide – Water (as water vapor) • Lesser amounts – CO, H 2, NH 3, H 2 S and CH 4

Venus, Earth & Mars Comparison Venus Earth Mars Pressure CO 2 (>98%) N 2 (1%) Ar (1%) O 2 (0%) 91 atm CO 2 (0. 03%) N 2 (79%) Ar (1%) O 2 (20%) 1 atm CO 2 (96%) N 2 (2. 5%) Ar (1. 5%) O 2 (2. 5%) 0. 006 atm Temperature 740 K* 290 K ** 240 K *** Gravity 8. 87 m/s 2 9. 87 m/s 2 3. 72 m/s 2 Atmosphere *870º F **70º F *** -30º F

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

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

Chemical Evolution • Requires a non-oxidizing atmosphere – No oxygen initially • Requires a sources 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

Chemical Reactions & Chemical Reactions • Need to speed up chemical processes • Reactions are sped up by • Increasing concentrations of reactants • Temperature • Common phases • Solvent effects • Catalyst

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

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

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

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

RNA Life • Book segment by B. Alberts http: //www. ncbi. nlm. nih. gov/books/NBK 26 876/ • http: //exploringorigins. org/timeline. html • https: //www. princeton. edu/~achaney/tmve/ wiki 100 k/docs/RNA_world_hypothesis. htm l

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

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

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

Stromatolites

Mono Lake, California

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

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

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