Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43NSCI 314LIFE IN THE COSMOS7 - The Origin and Evolution of Life on Earth Dr. Karen KolehmainenDepartment of Physics, CSUSBhttp://physics.csusb.edu/~karen/WHERE DID LIFE BEGIN?MAYBE LIFE WAS DELIVERED TO EARTH FROM AN EXTRATERRESTRIAL SOURCE, AS OPPOSED TO HAVING ORIGINATED HERE (“PANSPERMIA”).–UNLIKELY, ALTHOUGH SIMPLE ORGANIC MOLECULES MAY HAVE BEEN DELIVERED TO EARTH VIA COMETARY IMPACTSPROBABLY NOT ON DRY LAND–IMPACTS, UV RADIATION (NO OZONE LAYER YET), AND/OR OTHER ENVIRONMENTAL HAZARDS WOULD MOST LIKELY HAVE WIPED IT OUT–HARD FOR MOLECULES TO LINK UP TO PRODUCE LONG POLYMERS UNLESS DISSOLVED IN A LIQUIDPOSSIBILITIES:–OCEANS NEAR HYDROTHERMAL VENTS –HOT SPRINGS–SMALL POOLS OF WATER (TIDEPOOLS?)–INSIDE ROCKSDID LIFE BEGIN AT HYDROTHERMAL VENTS?PRO:–ENVIRONMENT PROTECTED FROM IMPACTS (UNLESS OCEAN VAPORIZES COMPLETELY), UV RADIATION, AND OTHER ENVIRONMENTAL HAZARDS ON EARLY EARTH–ORGANIC MOLECULES CAN INTERACT & LINK TOGETHER TO MAKE LARGER MOLECULES MORE EASILY IF DISSOLVED IN WATER– DNA EVIDENCE IS SUGGESTIVE OF THISCON:–LIFETIME OF AN INDIVIDUAL VENT IS SHORT (FEW CENTURIES)–ORGANIC MATERIALS QUICKLY DILUTED IN SEAWATER–MAYBE TOO HOT BOTTOM LINE: SEEMS LIKE A GOOD POSSIBILITYDID LIFE BEGIN IN SMALL POOLS OF WATER (MAYBE TIDEPOOLS)? PRO:–ORGANIC MOLECULES CAN INTERACT & LINK TOGETHER TO MAKE LARGER MOLECULES MORE EASILY IF DISSOLVED IN WATER–IN A SMALL BODY OF WATER, CHEMICALS CAN BECOME MORE CONCENTRATED THAN IN A LARGE BODY OF WATER LIKE AN OCEAN (ESPECIALLY AS POOL EVAPORATES).–TIDES OCCASIONALLY BRING IN NEW MATERIALS INTO TIDEPOOLS.–SOLID SUBSTRATE (CLAY) AT THE BOTTOM OF THE POOL COULD AID IN LINING UP MONOMERS TO FORM POLYMERS, AND SELECTING ONE HANDEDNESS (ISOMER) OF MOLECULES.CON:–SMALL AMOUNT OF WATER DOESN'T PROVIDE ENOUGH PROTECTION FROM ENVIRONMENTAL HAZARDS LIKE IMPACTS AND UV RADIATION–MAY NOT BE ENOUGH ENERGY AVAILABLEMILLER-UREY EXPERIMENTSATTEMPTS TO CREATE LIFE IN THE LABORATORYPROVIDE A MIXTURE OF GASES SIMILAR TO THAT IN THE EARLY ATMOSPHEREPROVIDE WATER TO SIMULATE OCEANS OR POOLSPROVIDE A SOURCE OF ENERGYWAIT AND SEE WHAT HAPPENSWATERGASES: (DIFFERENT MIXTURES HAVE BEEN TRIED)•H2O (WATER VAPOR)•CO2(CARBON DIOXIDE)•N2(NITROGEN)•H2(HYDROGEN)•CH4(METHANE)•NH3(AMMONIA)ENERGY:•HEAT•ELECTRIC SPARK (LIGHTNING)•ULTRAVIOLET LIGHTTIME (WAIT A FEW DAYS TO WEEKS)INGREDIENTS FOR MILLER-UREY EXPERIMENTSRESULTSMANY ORGANIC MOLECULES ARE PRODUCED, INCLUDING:SUGARS (INCLUDING RIBOSE)FATS OR LIPIDSAMINO ACIDS (50% L AND 50% D)GENETIC BASESNOTE: IF OXYGEN IS PRESENT, THESE MOLECULES ARE NOT FORMED! (IF OXYGEN IS PRESENT, EVERYTHING  CO2 & H2O)LIMITATIONSNOT ALL IMPORTANT ORGANIC MOLECULES ARE FORMED.NO ACTUAL LIVING ORGANISMS ARE FORMED.  WHY? MAYBE MORE TIME IS NEEDED (MILLIONS OF YEARS, NOT JUST A FEW WEEKS OR MONTHS) – AFTER ALL, LIFE ON EARTH HAD HUNDREDS OF MILLIONS OF YEARS TO GET STARTED!MAYBE SOME KEY INGREDIENT IS MISSING.MAYBE THE BASIC IDEA IS WRONG.SOURCES OF SIMPLE ORGANIC MOLECULES ON EARLY EARTHMILLER-UREY TYPE REACTIONS IN–SMALL POOLS OF WATER–OCEANS NEAR HYDROTHERMAL VENTS–OTHER LOCATIONS?DELIVERY VIA COMET AND ASTEROID IMPACTSTHESE MAY ALL HAVE PLAYED A ROLEBUT THIS ISN’T LIFE YET!WHAT HAPPENED NEXT?STEPS IN THE ORIGIN OF LIFESIMPLE ORGANIC MOLECULES (MONOMERS) WERE PRODUCED VIA CHEMICAL REACTIONS AND/OR DELIVERED VIA COMETARY IMPACTS.SIMPLE ORGANIC MOLECULES COMBINED TO MAKE LONG POLYMERSSOME OF THE LONG POLYMERS MUST HAVE BEEN SELF-REPLICATING (LIKE DNA).POLYMERS WERE ENCLOSED INSIDE A “CELL” THAT WAS SEPARATED FROM ITS ENVIRONMENT BY A MEMBRANE.POLYMERIZATIONHOW DID SIMPLE ORGANIC MOLECULES (MONOMERS) JOIN UP TO MAKE LONG POLYMERS?IF IMMERSED IN A LIQUID, THEY CAN MOVE AROUND AND COMBINE MORE EASILY.THEY MAY HAVE ORGANIZED THEMSELVES ON SOLID SURFACES, LIKE CLAY. –THIS REQUIRES A SOLID SUBSTRATE, SUCH AS THE BOTTOM OF A BODY OF WATER.–THE SHAPE OF THE SURFACE MAY HELP THE MONOMERS LINE UP PROPERLY TO LINK TOGETHER. –IN SOME CASES, THE SURFACE MAY HELP THEM LINE UP IN SUCH A WAY AS TO SELECT ONE HANDEDNESS FOR THE RESULTING POLYMER.–EXPERIMENTS HAVE SHOWN THAT POLYMERS CAN BE BUILT UP THIS WAY ON CLAY SURFACES.PROTEINS, DNA, AND RNADNA AND RNA CAN REPLICATE THEMSELVES (AN IMPORTANT CHARACTERISTIC OF LIFE).IN MODERN LIVING ORGANISMS, DNA AND PROTEINS INTERACT IN IMPORTANT WAYS.–INSTRUCTIONS FOR CONSTRUCTING PROTEINS ARE CARRIED IN DNA.–PROTEINS ARE IMPORTANT IN CONSTRUCTING DNA. (SOME ARE NEEDED FOR DNA REPLICATION).PROBLEM: WHICH CAME FIRST?POSSIBLE SOLUTION: RNA MAY HAVE PRECEDED DNA AS GENETIC MATERIAL IN EARLIEST LIFE FORMS (LIKE IN SOME MODERN VIRUSES). RNA CAN PLAY THE ROLES OF BOTH DNA AND PROTEINS. AT SOME POINT, A “MISTAKE” IN RNA REPLICATION RESULTED IN DNA BEING PRODUCED.ORIGIN OF CELLSALL LIFE ON EARTH OF MADE OF CELLS.A CELL IS SEPARATED FROM ITS ENVIRONMENT BY A MEMBRANE.ORGANIC MOLECULES ARE KEPT CLOSE TOGETHER, MAKING IT EASIER FOR THEM TO INTERACT, IF ENCLOSED INSIDE A CELLEXPERIMENTS SUGGEST HOW CELLS MAY HAVE ORIGINATED:–ORGANIC POLYMERS DISSOLVED IN WATER CAN EASILY GROUP TOGETHER INTO DROPLETS.–MEMBRANES FORM EASILY UNDER MANY CONDITIONS. –CLAY SURFACES ALSO CAN HELP MEMBRANES TO FORM.–EXPERIMENTS WITH CLAY SURFACES AT THE BOTTOM OF A POOL OF WATER HAVE PRODUCED “PRE-CELLS” - A DROPLET ENCLOSED BY A MEMBRANE WITH RNA INSIDE!MUTATIONSCHANGES IN THE SEQUENCE OF BASES IN DNA DUE TO MISTAKES IN DNA REPLICATION. THESE INCLUDE:–A MISTAKE IN WHICH BASE IS INSERTED INTO A GROWING DNA STRAND. FOR EXAMPLE, IF THERE IS A C IN THE TEMPLATE STRAND, A G SHOULD BE ATTACHED TO IT, BUT AN A MAY BE ATTACHED INSTEAD. (THE C AND A WON'T STICK TOGETHER AS WELL AS THE C AND G WOULD.) –A SINGLE BASE THAT IS ADDED OR DELETED–A SEQUENCE OF SEVERAL BASES THAT IS DUPLICATED OR DELETEDMUTATIONS OCCUR EITHER RANDOMLY (LESS THAN ONCE PER BILLION BASES), OR BECAUSE OF EXPOSURE TO HIGH ENERGY PHOTONS (ULTRAVIOLET, X-RAYS, OR GAMMA RAYS), OTHER HIGH ENERGY PARTICLES, OR