Origin of life

The facts…… hidden somewhere The story….… unrevealed The truth… not known exactly The path… untraced An attempt to explore the way!!! ORIGIN OF chemistry, LIFE and An effort to blend biology, physics in the search to identify and understand the origin of life in the universe It’s a “Journey Back In Time”… By Kalpana Stuti, Ritu, Gauri Miranda House ORIGIN OF LIFE BIG BANG Cosmic dust and gases+ H2O Oceans Haldane soup Reducing atmosphere(gases like CH4,NH3,N2,CO2,H2O responsible for abiotic synthesis of organic compounds) OPARIN-HALDANE THEORY Haldane Soup Simple Molecules Complex Molecules (building blocks) Aggregates (coacervates and microspheres) Microsphere Protocells( proprimitive stage before formation of true cell Proto cells + nucleic acid = self replicating system “CELL” ENERGY YIELDING SYSTEM • “Cell” • Chlorophyll Energy Yielding System development Photosynthesis O2 evolved Ozone Formation (shielding effect) • Atmosphere • Evolution changed to oxidizing from reducing of photosynthesis which is followed by respiration CELL Replication Metabolism Homeostasis Anaerobes Aerobes Chemotrophs Heterotrophs Chemoheterotrophs Prokaryotic Cells Endosymbiotic Theory Chemoautotrophs Eukaryotic cell How Eukaryotic Cell Changed to Multicellular Organism… EVIDENCES??? • Geological Evidence • Precambrian Fossil Evidence • Laboratory Evidence GEOLOGICAL EVIDENCE • Sedimentary rock in past 500 million years are silicate sands clay, quartz type indicating oxidizing conditions • Ancient Precambrian sediments containing sands with reduced iron minerals found in Canada, Brazil, South Africa • Banded iron ore deposits with mixed oxidation states in Quinland, Russia, India and Australia Giant Tube Worms: RIFTIA • On the bottom of the ocean around deep-sea hydrothermal vents, there is a profusion of life that thrives on the hydrogen sulfide (H S) gas released from the vents.and live inside hard, shell-like protective tubes that attach to the rocks Giant tubeworms that live around hydrothermal vents on the sea floor These creatures are about the size of your hand in shallower waters, but in the ocean's deep they have been found as big as eight feet long! How they live… • These creatures lack mouths, anuses, intestines and stomachs, and scientists were at a loss to explain how these were getting nutrients to survive and grow • Their insides are lined with bacteria that oxidize the H S, turning it into usable nutrients for the worms • The bacteria, in turn, benefit from the relationship because the worms deliver blood containing hemoglobin which helps the bacteria to break down the sulfides • They live in a symbiotic relationship with a bacteria that may hold clues as to how life on earth began billions of years ago BIOCHEMISTRY AT THE VENTS • H S Released from vents Oxidation by bacteria Energy released helps in fixing CO2 into small organic molecules So this cycle is the same metabolic pathway that is utilized by plants in photosynthesis takes inorganic carbon dioxide and fixes it into organic compounds that are then food But, the difference here, the critical difference, is that rather than using sunlight, these animals and bacteria are completely independent of sunlight They utilize chemical energy to power that reaction So, ever imagined a life out of toxic Hydrogen Sulphide?! Chemical of Life - Ammonia, Produced at Vents • Hydrothermal vents were the most likely site for NH production where inorganic sulphides acted as catalyst N2 +NO2 +N03 Presumed to be present in ancient sea FeO 46% yield 15 FeS, 500oC 89% yield, 15 NH3 Stable upto 800oC Powdered Basalt 20% yield RESULTS • Since NH cannot survive at temperature above 800oC indicates that nitrogen would have been present only as N during early phase of earth’s development • Life can exist on thermal and chemical energy as opposed to just sunlight as had been thought in the past And so what was realized is that photosynthesis was not the only way to support life THE BIG BANG First proposed by George Lemaître in 1927 Salient Features •Our Universe began as an infinitesimally small, infinitely hot, infinitely dense singularity •Then it inflated (big bang), expanded and cooled to the size and temperature of our present Universe Timeline of the Big Bang What happened after the Big Bang? Time since Big Bang T (K) < 10-43s Quantum era ~ 10-35s - 10-33s Inflationary epoch ~ 10-6s 1013K Quark > Hadron transition Time since Big Bang 0.01s 15s T (K) 1011K · The Universe expands rapidly, scale is doubled every 0.02s · it cools, T ~ 1/R x 109K · Temperature is below threshold for creation of electron/positron pairs · e+/ e- annihilate · The Universe is "reheated" about 35% by annihilation 109K Era of Nuclear Reactions · Nuclei begin to hold together Time since Big Bang T (K) &1/2 108K 106yr 109yr End of Nuclear Reactions neutrons have been "used-up" forming 4He Universe is now 90% H nuclei( p+) & 10% He nuclei 4000K Era of Recombination nuclei & electrons "recombine to form atoms Era of Galaxy Formation Evidences for the Big Bang •Galaxies are moving away from us at speeds proportional to their distance This is called "Hubble's Law," named after Edwin Hubble (1889-1953) who discovered this phenomenon in 1929 •The abundance of the "light elements" Hydrogen and Helium found in the observable universe are thought to support the Big Bang model of origins •Cosmic Background Radiation predicted by Cosmologist George Gamov in 1948 and discovered by Arno Penzias & Robert Wilson of Bell Labs in 1965   THE COMPETITORS … FOR THE THEORY ON ORIGIN OF THE UNIVERSE • • • • • The Bubble Universe / Andre Linde's Self Creating Universe The Inflationary Theory (1981, Alan Guth ) The Protouniverse (white hole theory) The Steady State Theory (late 1940’s ) The Oscillating Universe Theory (1960’s -70’s ) References • • • • • • The Cosmos by Carl Sagan • Sawyer, Kathy “Signs of Earliest Life in Ocean Depths—Scalding Habitat May Have Supported Microbes, Fossils Indicate,” Washington Post, June 8, 2000 Text Book of Biology by Campbell The Scientific American http://scienceweek.com www.nationalgeographic.com Humphris, Susan E and Tom McCollom “The Cauldron Beneath the Seafloor,” Oceanus, Vol 41, No 2, 1998, 18 Nobody understands the origin of life If they say they do, they are probably trying to fool you — Ken Nealson, 2002 THANK YOU [...]... that life on Earth originated in the ocean and strong evidence now suggests that the earliest life on our planet occurred in the depths the ocean in the absence of heat and light." Millerof and Urey found Pulse of the Planet, American Museum of Natural History Photograph from National Geographic magazine Deep-sea Vents • • Their discovery in late 1970’s stretched our concept of the origin of life. .. out how the offspring of such organisms disperse over long stretches of inhospitable seafloor to colonize widely separated vent systems Giant Clams The size of deep-sea giant clams is evident from the hands of a scientist holding them (Photograph by William R Normark, USGS.) Giant Tube Worms: RIFTIA • On the bottom of the ocean around deep-sea hydrothermal vents, there is a profusion of life that thrives... the possibility that earlier vents supplied the energy and chemical precursors Can life exist and that too thousands of meters beneath the surface of sea in absence of sunlight? for origin of protobionts Exploring the deep ocean floor View of the first hightemperature vent (380°C) ever seen by scientists during a dive of the deep-sea submersible Alvin in 1979 Such geothermal vents are called smokers... organisms, might have evolved on the surface of comic dust grains in space and then been transported to the Earth's surface by comets and meteorites Where did life begin??? • There is an ongoing debate regarding the most probable site of life' s origins • The prevailing paradigm - life began near the ocean's surface, bathed in sunlight • Current Research - life arose near deep hydrothermal vents which... genesis of life) have been found in meteorites –  It means that at least prebiotic chemistry that leads to the primordial soup might be going on there Evidences in support of this theory • In 1969, a meteorite landed in Australia that was 12% water and contained traces of 92 amino acids Inference- It points to not only the presence of organic compounds in outer space, but also the capacity of such... the difference here, the critical difference, is that rather than using sunlight, these animals and bacteria are completely independent of sunlight They utilize chemical energy to power that reaction So, ever imagined a life out of toxic Hydrogen Sulphide?! Chemical of Life - Ammonia, Produced at Vents • Hydrothermal vents were the most likely site for NH production where inorganic 3 sulphides acted as... Universe is "reheated" about 35% by annihilation 109K Era of Nuclear Reactions · Nuclei begin to hold together Time since Big Bang T (K) 3 &1/2 min 108K 106yr 109yr End of Nuclear Reactions neutrons have been "used-up" forming 4He Universe is now 90% H nuclei( p+) & 10% He nuclei 4000K Era of Recombination nuclei & electrons "recombine to form atoms Era of Galaxy Formation Evidences for the Big Bang •Galaxies... Edwin Hubble (1889-1953) who discovered this phenomenon in 1929 •The abundance of the "light elements" Hydrogen and Helium found in the observable universe are thought to support the Big Bang model of origins •Cosmic Background Radiation predicted by Cosmologist George Gamov in 1948 and discovered by Arno Penzias & Robert Wilson of Bell Labs in 1965 ... temperature above 800oC indicates that nitrogen would 3 have been present only as N during early phase of earth’s development 2 • Life can exist on thermal and chemical energy as opposed to just sunlight as had been thought in the past And so what was realized is that photosynthesis was not the only way to support life THE BIG BANG First proposed by George Lemaître in 1927 Salient Features •Our Universe began... temperature of our present Universe Timeline of the Big Bang What happened after the Big Bang? Time since Big Bang T (K) < 10-43s Quantum era ~ 10-35s - 10-33s Inflationary epoch ~ 10-6s 1013K Quark > Hadron transition Time since Big Bang 0.01s 15s 3 min T (K) 1011K · The Universe expands rapidly, scale is doubled every 0.02s · it cools, T ~ 1/R 3 x 109K · Temperature is below threshold for creation of electron/positron ... chemical precursors Can life exist and that too thousands of meters beneath the surface of sea in absence of sunlight? for origin of protobionts Exploring the deep ocean floor View of the first hightemperature... Pulse of the Planet, American Museum of Natural History Photograph from National Geographic magazine Deep-sea Vents • • Their discovery in late 1970’s stretched our concept of the origin of life. .. untraced An attempt to explore the way!!! ORIGIN OF chemistry, LIFE and An effort to blend biology, physics in the search to identify and understand the origin of life in the universe It’s a “Journey