Origin of Life

1. Origin of Life Lecture Ten, Feb. 7, 2003 Reptiles, M C Escher

2. Course Project • Topic of your choosing related to class. • Proposal (1-2 pages) Feb. 14, 2003. • Project background (3-5 pages) Mar. 28, 2003. • Project (10 pages) April 25.

3. Pathfinder the Race to Mars • 60 min video on web site. • 1996 Mars Global Surveyor lunched to orbit and map Mars. • Also Mars Pathfinder with its small rover. • These followed failed Mars Observer in 1993. • See Manyrovers_full.jpg (note, this is a 7.4 MB image)

4. The Doomsday Asteroid • 60 min Video about impact of comet Shoemaker Levy 9 with Jupiter and present day threat from impacts. • Keck Telescope infrared images of collision.

5. Hubble Image of Impact Plum Impact site itself just out of site beyond rim

6. Gamma Ray Bursts • The Nova program Death Stars discusses Gamma Ray bursts. These are the most energetic explosions since the Big Bang. They have now been detected billions of light years from Earth. Simulation of collapse of giant rotating star to produce two gamma ray jets.

7. Project • Almost any topic of interest to you and related to the class is possible. • Try and discuss as much of the science, covered in class, as possible. • Example of a project: “The Movie 2001 and The Evolution of Man”, by C Horowitz. See paper copy or class web site. You should read this paper! Note, how it discusses the movie “2001 A Space Odyssey” in terms of many of the topics covered in class.

8. Ideas for Projects • Big Bang/ creation of Universe. • Supernovae, neutron stars, and or black holes. • Impacts of comets and asteroids. • Death of dinosaurs (See for example, “T.Rex and the crater of doom” by L. Alvarez). • Impact of Shoemaker Levy 9 with Jupiter (See for example, “Impact Jupiter” by D. Levy) • Present day impact threat.

9. Project Ideas Continued • Mars • Robotic exploration • Manned mission (See for example, “The Case For Mars”, R. Zubrin) • Colonization or terrafarming (See text) • Discuss Science in a Science Fiction Story. • 2001, 2010… by A. C. Clark • “Andromeda Strain” by M. Crichton • “Red, (Green, Blue) Mars” by K. S. Robinson • Lots and Lots to chose from… • Space exploration

10. Ideas Continued • Origin of Life • Extrasolar planets (see for example, “Worlds Unnumbered” by D. Goldsmith) • Interstellar Flight and Colonization. • SETI • …

11. Earth’s Thermostat • Amount of CO2 in atmosphere controlled by absorption to make carbonate rocks or out-gassing from volcanoes. • This changes greenhouse effect and Earth’s temperature. • Earth’s temperature has been remarkably stable over its history despite an increase in the Sun’s output. • There must have been more CO2 at early times and this somehow decreased in a way that compensated the increase in the Sun’s output.

13. Earth’s Atmosphere Over Time

14. We don’t understand this Thermostat • We don’t understand many of the mechanisms which regulate CO2. • How much more CO2 will lead to a runaway greenhouse effect such as what happened to Venus? • What will the ultimate effect of human produced CO2 be (global warming)? • How close did Earth come to losing CO2 and going into a permanent global ice age (“Snowball Earth”)?

15. Venus is Hot as Hell • Atmosphere is 90 times thicker then Earth and mostly CO2. • Greenhouse effect raises temp. by 400 C to about 470 C (hot enough to melt lead). • Not a likely place for life.

16. Mars was once Warmer and Wetter • In the past, Mars atmosphere had much more CO2. • This allowed greenhouse effect to raise temp. above 0 C. • Mars has since lost most of its atmosphere for unknown reasons, perhaps absorption in rocks.

17. Earth is Geologically Alive. • We are lucky that Earth’s core is still hot and this heat flow drives convection, plate tectonics and generates magnetic field. • Plate tectonics may help regulate CO2 in atmosphere. • Note, no other planet in solar system appears to have plate tectonics. • Earth’s temp. remained remarkably stable despite warming Sun. • Timeline: Big Bang 13 Bya, creation of chemical elements 12-5 Bya, formation of Earth 4.6 Bya, formation of Moon in Big Whack 4.5 Bya, Large impact basins on Moon 3.8 Bya, Origin of life 3.8 Bya.

18. Origin of Life According to Michelangelo

19. Origin of Life • According to Mel Brooks • Real Media clip of creation of life from Young Frankenstein

20. The Chemistry of Life • Start with very simple chemicals such as CO2, H2O, N2, NH3. • Temperature and pressure allow liquid H2O. • Energy source: could be ultraviolet radiation from Sun, Lightening, Chemical reactions. • Somehow produce the building blocks of life.

21. Amino Acids: Building Blocks of Life • Amino acids are chemical compounds with amine groups (containing nitrogen, N) and weak acid groups (HO2C) that can be linked together to form long chains called proteins. • Example: Amino acid Alanine H H Amine group Chemistry 101: Note, 4 bonds for C, 3 bonds for N, 2 for O and 1 for H N C H H O C C H H O H Acid group

22. Chemistry 101 • Remember • Hydrogen, H 1 electron, 1 in outer shell • Carbon, C 6 electrons, 4 in outer shell • Nitrogen, N 7 electrons, 5 in outer shell • Oxygen, O 8 electrons, 6 in outer shell • Neon, Ne 10 electrons, 8 in outer shell • Ne is a noble gas (unreactive) with a closed electron shell. • Chemical bond (covalent bond): sharing of electrons between two atoms.

23. Chemical bonds • Atoms like to bond to form closed shells. • C likes to form 4 bounds (4 shared electrons plus the 4 it starts with gives 8) • N likes to form 3 bounds. • O likes to form 2 bounds. • H likes to form 1 bound. • Draw bounds as single line (share one electron) or double line for a double bound where two electrons are shared.

24. Two amino acids H H N C H H O C C H H O H H H N Amine group C H H Acid group O C C H H • The amine group of one amino acid can react with the acid group of another to produce a molecule of H2O and the joining of the two. O H

25. H These react to form H2O H N C H H O C C H H O H H H N H H N C H H O C C H C H H H2O + O C C O H H H N H H Two amino acids C H H O C C H H O H One longer chain that still has an amine and an acid group

26. Proteins are Made of Amino Acids • Amino acids have an amine group (N) and an acid group (CO2H) • Can bind amino acids together to produce long molecules called proteins. • Proteins form the basis for life on Earth. • Earth life uses proteins made from 20 different amino acids strung together in definite orders. • Where did the amino acids come from? • How were they put together in the correct order?

27. The Chemistry of Life • Short real video clip about the chemistry of life from the discovery channel.

28. Life made from 20 amino acids Glycine Alanine Valine Lysine Note, carbons at ends of lines and hydrogens are not shown

29. Red is oxygen (acid) and blue is nitrogen (amine) group

30. A Protein • To specify a unique protein you must specify which one of the 20 amino acids occurs first, which amino acid occurs 2nd and so on. • A protein may be thousands of amino acids long. • Need a long string of thousands of numbers each of which goes from 1 to 20. • Example 5-12-3-3-3-2-20-19-11-…

31. The Left Hand of God • A given amino acid can come in two mirror image forms. • Life on Earth only uses the left handed form. • We don’t understand the origin of this chirality (Greek word for hand).

32. Miller Experiment • Stanley Miller, a graduate student of Harold Urey, in 1953 placed H2O, H2, NH3, CH4 in a flask. Constantly boiled and recondensed the H2O and added an electrical discharge (lightning) for energy. • Spectacular results: produced lots of amino acids and other organic compounds.

33. For next time • Read chap. 4 of Jakosky about the earliest life and read “Vital Dust", pages 1-23 in course packet about origin of life. • Think about your course project. Proposal (1-2 pages) due Feb. 14, 2003. • Next lecture, Monday Feb. 10, 2003, “Life in a Bottle”.