Origin of LifeOrigin of Life

Lecture Ten, Feb. 7, 2003Lecture Ten, Feb. 7, 2003

Reptiles, Reptiles, M C M C EscherEscher

Course ProjectCourse Project

• Topic of your choosing related to Topic of your choosing related to class.class.

• Proposal (1-2 pages) Feb. 14, 2003. Proposal (1-2 pages) Feb. 14, 2003.

• Project background (3-5 pages) Mar. Project background (3-5 pages) Mar. 28, 2003. 28, 2003.

• Project (10 pages) April 25.Project (10 pages) April 25.

Pathfinder the Race to MarsPathfinder the Race to Mars

• 60 min video on web 60 min video on web site.site.

• 1996 Mars Global 1996 Mars Global Surveyor lunched to Surveyor lunched to orbit and map Mars. orbit and map Mars.

• Also Mars Pathfinder Also Mars Pathfinder with its small rover.with its small rover.

• These followed failed These followed failed Mars Observer in 1993.Mars Observer in 1993.

• See See Manyrovers_full.jpgManyrovers_full.jpg (note, this is a 7.4 MB (note, this is a 7.4 MB image)image)

The Doomsday AsteroidThe Doomsday Asteroid

• 60 min Video 60 min Video about impact of about impact of comet comet Shoemaker Levy Shoemaker Levy 9 with Jupiter 9 with Jupiter and present day and present day threat from threat from impacts.impacts.

• Keck Telescope iKeck Telescope infrared images nfrared images of collision. of collision.

Hubble Image of Impact Hubble Image of Impact PlumPlum

Impact site itself just out of site beyond Impact site itself just out of site beyond rimrim

Gamma Ray BurstsGamma Ray Bursts

• The Nova program The Nova program Death Stars Death Stars discusses Gamma discusses Gamma Ray bursts. These Ray bursts. These are the most are the most energetic explosions energetic explosions since the Big Bang. since the Big Bang. They have now They have now been detected been detected billions of light years billions of light years from Earth.from Earth.

Simulation of Simulation of collapse of giant collapse of giant rotating star to rotating star to produce two gamma produce two gamma ray jets.ray jets.

ProjectProject

• Almost any topic of interest to you and Almost any topic of interest to you and related to the class is possible.related to the class is possible.

• Try and discuss as much of the science, Try and discuss as much of the science, covered in class, as possible.covered in class, as possible.

• Example of a project: “The Movie 2001 and Example of a project: “The Movie 2001 and The Evolution of Man”, by C Horowitz. See The Evolution of Man”, by C Horowitz. See paper copy or class web site. You should paper copy or class web site. You should read this paper! Note, how it discusses the read this paper! Note, how it discusses the movie “2001 A Space Odyssey” in terms of movie “2001 A Space Odyssey” in terms of many of the topics covered in class. many of the topics covered in class.

Ideas for ProjectsIdeas for Projects

• Big Bang/ creation of Universe.Big Bang/ creation of Universe.

• Supernovae, neutron stars, and or black Supernovae, neutron stars, and or black holes.holes.

• Impacts of comets and asteroids.Impacts of comets and asteroids.– Death of dinosaurs (See for example, “T.Rex Death of dinosaurs (See for example, “T.Rex

and the crater of doom” by L. Alvarez).and the crater of doom” by L. Alvarez).– Impact of Shoemaker Levy 9 with Jupiter (See Impact of Shoemaker Levy 9 with Jupiter (See

for example, “Impact Jupiter” by D. Levy)for example, “Impact Jupiter” by D. Levy)– Present day impact threat.Present day impact threat.

Project Ideas ContinuedProject Ideas Continued

• MarsMars– Robotic explorationRobotic exploration– Manned mission (See for example, “The Case Manned mission (See for example, “The Case

For Mars”, R. Zubrin)For Mars”, R. Zubrin)– Colonization or terrafarming (See text)Colonization or terrafarming (See text)

• Discuss Science in a Science Fiction Story.Discuss Science in a Science Fiction Story.– 2001, 2010… by A. C. Clark2001, 2010… by A. C. Clark– ““Andromeda Strain” by M. CrichtonAndromeda Strain” by M. Crichton– ““Red, (Green, Blue) Mars” by K. S. RobinsonRed, (Green, Blue) Mars” by K. S. Robinson– Lots and Lots to chose from…Lots and Lots to chose from…

• Space explorationSpace exploration

Ideas ContinuedIdeas Continued

• Origin of LifeOrigin of Life

• Extrasolar planets (see for example, Extrasolar planets (see for example, “Worlds Unnumbered” by D. “Worlds Unnumbered” by D. Goldsmith)Goldsmith)

• Interstellar Flight and Colonization.Interstellar Flight and Colonization.

• SETISETI

• ……

Earth’s Thermostat Earth’s Thermostat

• Amount of COAmount of CO22 in atmosphere controlled by in atmosphere controlled by absorption to make carbonate rocks or out-absorption to make carbonate rocks or out-gassing from volcanoes.gassing from volcanoes.

• This changes greenhouse effect and Earth’s This changes greenhouse effect and Earth’s temperature.temperature.

• Earth’s temperature has been remarkably Earth’s temperature has been remarkably stable over its history despite an increase in stable over its history despite an increase in the Sun’s output.the Sun’s output.

• There must have been more COThere must have been more CO22 at early at early times and this somehow decreased in a way times and this somehow decreased in a way that compensated the increase in the Sun’s that compensated the increase in the Sun’s output.output.

Earth’s Atmosphere Over Earth’s Atmosphere Over TimeTime

We don’t understand this We don’t understand this ThermostatThermostat• We don’t understand many of the We don’t understand many of the

mechanisms which regulate COmechanisms which regulate CO22..• How much more COHow much more CO22 will lead to a will lead to a

runaway greenhouse effect such as what runaway greenhouse effect such as what happened to Venus?happened to Venus?

• What will the ultimate effect of human What will the ultimate effect of human produced COproduced CO22 be (global warming)? be (global warming)?

• How close did Earth come to losing COHow close did Earth come to losing CO22 and going into a permanent global ice age and going into a permanent global ice age (“Snowball Earth”)?(“Snowball Earth”)?

Venus is Hot as HellVenus is Hot as Hell

• Atmosphere is 90 Atmosphere is 90 times thicker then times thicker then Earth and mostly COEarth and mostly CO22..

• Greenhouse effect Greenhouse effect raises temp. by 400 C raises temp. by 400 C to about 470 C (hot to about 470 C (hot enough to melt lead).enough to melt lead).

• Not a likely place for Not a likely place for life. life.

Mars was once Warmer and Mars was once Warmer and Wetter Wetter • In the past, Mars In the past, Mars

atmosphere had much atmosphere had much more COmore CO22..

• This allowed This allowed greenhouse effect to greenhouse effect to raise temp. above 0 C.raise temp. above 0 C.

• Mars has since lost Mars has since lost most of its most of its atmosphere for atmosphere for unknown reasons, unknown reasons, perhaps absorption in perhaps absorption in rocks.rocks.

Earth is Geologically Alive.Earth is Geologically Alive.

• We are lucky that Earth’s core is still hot and this We are lucky that Earth’s core is still hot and this heat flow drives convection, plate tectonics and heat flow drives convection, plate tectonics and generates magnetic field.generates magnetic field.

• Plate tectonics may help regulate COPlate tectonics may help regulate CO22 in in atmosphere.atmosphere.

• Note, no other planet in solar system appears to Note, no other planet in solar system appears to have plate tectonics.have plate tectonics.

• Earth’s temp. remained remarkably stable despite Earth’s temp. remained remarkably stable despite warming Sun.warming Sun.

• Timeline: Big Bang 13 Bya, creation of chemical Timeline: Big Bang 13 Bya, creation of chemical elements 12-5 Bya, formation of Earth 4.6 Bya, elements 12-5 Bya, formation of Earth 4.6 Bya, formation of Moon in Big Whack 4.5 Bya, Large formation of Moon in Big Whack 4.5 Bya, Large impact basins on Moon 3.8 Bya, Origin of life 3.8 impact basins on Moon 3.8 Bya, Origin of life 3.8 Bya.Bya.

Origin of Life According to Origin of Life According to Michelangelo Michelangelo

Origin of LifeOrigin of Life

• According to Mel BrooksAccording to Mel Brooks

• Real Media clip of creation of life Real Media clip of creation of life from from Young FrankensteinYoung Frankenstein

The Chemistry of LifeThe Chemistry of Life

• Start with very simple chemicals Start with very simple chemicals such as COsuch as CO22, H, H22O, NO, N22, NH, NH33..

• Temperature and pressure allow Temperature and pressure allow liquid Hliquid H22O.O.

• Energy source: could be ultraviolet Energy source: could be ultraviolet radiation from Sun, Lightening, radiation from Sun, Lightening, Chemical reactions.Chemical reactions.

• Somehow produce the building Somehow produce the building blocks of life. blocks of life.

Amino Acids: Building Blocks of Amino Acids: Building Blocks of LifeLife• Amino acids are chemical compounds with amine Amino acids are chemical compounds with amine

groups (containing nitrogen, N) and weak acid groups (containing nitrogen, N) and weak acid groups (HOgroups (HO22C) that can be linked together to form C) that can be linked together to form long chains called proteins.long chains called proteins.

• Example: Amino acid Alanine Example: Amino acid Alanine

HHOO CC

OO

CC

CC

NN

H H

HH

HH

HH

HH HH

Acid groupAcid group

Amine groupAmine group Chemistry Chemistry 101: Note, 4 101: Note, 4 bonds for C, 3 bonds for C, 3 bonds for N, 2 bonds for N, 2 for O and 1 for O and 1 for Hfor H

Chemistry 101Chemistry 101

• RememberRemember– Hydrogen,Hydrogen, H 1 electron, 1 in outer shellH 1 electron, 1 in outer shell– Carbon, Carbon, C 6 electrons, 4 in outer shellC 6 electrons, 4 in outer shell– Nitrogen, Nitrogen, N 7 electrons, 5 in outer shellN 7 electrons, 5 in outer shell– Oxygen,Oxygen, O 8 electrons, 6 in outer shellO 8 electrons, 6 in outer shell– Neon,Neon, Ne 10 electrons, 8 in outer shellNe 10 electrons, 8 in outer shell

• Ne is a noble gas (unreactive) with a Ne is a noble gas (unreactive) with a closed electron shell.closed electron shell.

• Chemical bond (covalent bond): sharing of Chemical bond (covalent bond): sharing of electrons between two atoms.electrons between two atoms.

Chemical bondsChemical bonds

• Atoms like to bond to form closed shells.Atoms like to bond to form closed shells.• C likes to form 4 bounds (4 shared C likes to form 4 bounds (4 shared

electrons plus the 4 it starts with gives 8)electrons plus the 4 it starts with gives 8)• N likes to form 3 bounds.N likes to form 3 bounds.• O likes to form 2 bounds.O likes to form 2 bounds.• H likes to form 1 bound.H likes to form 1 bound.• Draw bounds as single line (share one Draw bounds as single line (share one

electron) or double line for a double bound electron) or double line for a double bound where two electrons are shared.where two electrons are shared.

HHOO CC

OO

CC

CC

NN

H H

HH

HH

HH

HH HH

HHOO CC

OO

CC

CC

NN

H H

HH

HH

HH

HH HH

Two amino Two amino acidsacids

• The amine group of one amino acid can The amine group of one amino acid can react with the acid group of another to react with the acid group of another to produce a molecule of Hproduce a molecule of H22O and the joining O and the joining of the two. of the two.

Acid Acid grougroupp

Amine Amine groupgroup

HHOO CC

OO

CC

CC

NN

H H

HH

HH

HH

HH HH

HHOO CC

OO

CC

CC

NN

H H

HH

HH

HH

HH HH

OO CCCC

CC

NN

H H

HH

HH

HH

HH HH

HHOO CC

OO

CC

CC

NN

H H

HH

HH

HH

HH

Two amino acidsTwo amino acids

One longer chain that still has an amine and an acid One longer chain that still has an amine and an acid groupgroup

HH22O +O +

ThesThese e react react to to form form HH22OO

Proteins are Made of Amino Proteins are Made of Amino AcidsAcids• Amino acids have an amine group (N) and Amino acids have an amine group (N) and

an acid group (COan acid group (CO22H)H)• Can bind amino acids together to produce Can bind amino acids together to produce

long molecules called proteins.long molecules called proteins.• Proteins form the basis for life on Earth.Proteins form the basis for life on Earth.• Earth life uses proteins made from 20 Earth life uses proteins made from 20

different amino acids strung together in different amino acids strung together in definite orders.definite orders.

• Where did the amino acids come from?Where did the amino acids come from?• How were they put together in the correct How were they put together in the correct

order?order?

The Chemistry of LifeThe Chemistry of Life

• Short real video clip about the Short real video clip about the chemistry of lifechemistry of life from the discovery from the discovery channel. channel.

Life made from 20 amino Life made from 20 amino acidsacids

GlycineGlycine AlanineAlanine

ValineValine LysineLysine

Note, carbons at ends of lines and hydrogens are not Note, carbons at ends of lines and hydrogens are not shownshown

Red is oxygen (acid) and blue is nitrogen (amine) Red is oxygen (acid) and blue is nitrogen (amine) groupgroup

A ProteinA Protein

• To specify a unique protein you must To specify a unique protein you must specify which one of the 20 amino acids specify which one of the 20 amino acids occurs first, which amino acid occurs 2occurs first, which amino acid occurs 2ndnd and so on.and so on.

• A protein may be thousands of amino A protein may be thousands of amino acids long.acids long.

• Need a long string of thousands of Need a long string of thousands of numbers each of which goes from 1 to 20.numbers each of which goes from 1 to 20.

• Example 5-12-3-3-3-2-20-19-11-…Example 5-12-3-3-3-2-20-19-11-…

The Left Hand of GodThe Left Hand of God

• A given amino acid A given amino acid can come in two can come in two mirror image forms.mirror image forms.

• Life on Earth only Life on Earth only uses the left handed uses the left handed form.form.

• We don’t We don’t understand the understand the origin of this origin of this chirality (Greek word chirality (Greek word for hand).for hand).

Miller ExperimentMiller Experiment

• Stanley Miller, a graduate Stanley Miller, a graduate student of Harold Urey, in student of Harold Urey, in 1953 placed H1953 placed H22O, HO, H22, NH, NH33, , CHCH44 in a flask. Constantly in a flask. Constantly boiled and recondensed the boiled and recondensed the HH22O and added an electrical O and added an electrical discharge (lightning) for discharge (lightning) for energy.energy.

• Spectacular results: produced Spectacular results: produced lots of amino acids and other lots of amino acids and other organic compounds.organic compounds.

For next timeFor next time

• Read chap. 4 of Jakosky about the Read chap. 4 of Jakosky about the earliest life and read “Vital Dust", pages earliest life and read “Vital Dust", pages 1-23 in course packet about origin of 1-23 in course packet about origin of life.life.

• Think about your course project. Think about your course project. Proposal (1-2 pages) due Feb. 14, 2003.Proposal (1-2 pages) due Feb. 14, 2003.

• Next lecture, Monday Feb. 10, 2003, Next lecture, Monday Feb. 10, 2003, “Life in a Bottle”.“Life in a Bottle”.