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The Mechanism and History of Life Hannah Cebulla, Nikoli Brown, Katherine Lee, Nate Johnson, Jeremiah Hashley, Brett Gordon Earth’s Early Chemical Composition Pre-Earth -Protoplanetary disk -Roughly the mass of Jupiter -Heavier elements are closer to the Sun -Silicate dust and ice -H2, He are the dominant gases -99% gas Williams, Jonathan P., and Lucas A. Cieza. "Protoplanetary Disks and Their Evolution." Annual Review of Astronomy and Astrophysics (2011): 67-117. University of Hawaii Institute of Astronomy. Web. 11 Nov. 2016. 4.6 billion years ago -Core accretion model -Differentiation -Moon formed -Dominant elements: Fe (320,400 ppm), O (316,700 ppm), Mg (148,600 ppm), Si (145, 900 ppm), and Ni (17,200 ppm) -Most oxygen bound up as oxides rather than as O2 Kargel, J. S., and J. S. Lewis. The Composition and Early Evolution of Earth. N.p.: Icarus, Sept. 1993. PDF. 4 billion years ago -The Late Heavy Bombardment ends -Oceans form -Atmosphere forms -Most prominent chemicals are H2O (2699 ppm), C (526 ppm), and N (1.68 ppm) -Atmosphere comprised mostly of H2, H2O, NH3, CH4, and H2S Marty, Bernard. "The Origins and Concentrations of Water, Carbon, Nitrogen and Noble Gases on Earth." Earth and Planetary Science Letters 313-314 (2012): 56-66. ScienceDirect. Web. 11 Nov. 2016. 3.5 to 4 billion years ago -Organic molecules originate -Miller-Urey experiment -differing origin theories -Most important molecules for life: C, H2O, N, O, PO3 Sagan, Carl. Cosmos. New York: Random House, 1980. Print. 3.6 billion years ago -Life starts -Organic carbon discovered in ancient lava -May have begun around deep-sea hydrothermal vents -Simple, single-celled organisms -Doesn’t use O2 Furnes, Harald, Neil R. Banerjee, Karlis Muehlenbachs, Hubert Staudigel, and Maarten De Wit. "Early Life Recorded in Archean Pillow Lavas." Science 304.5670 (2004): 578-81. Science. Web. 12 Nov. 2016 3.4 billion years ago -Photosynthesis...ish -Not photosynthesis in its modern sense -Convert energy from the sun into energy for the cell -Still no oxygen -Probably didn’t use water Blankenship, Robert E. "Early Evolution of Photosynthesis." Plant Physiology 154 (2010): 434-38. Web. 12 Nov. 2016. 3 billion years ago -Plate tectonics puts N2 into atmosphere -Nitrogen is very important for life -Evidence: transition from mafic to felsic rocks Tang, Ming, Kang Chen, and Roberta L. Rudnick. "Archean Upper Crust Transition from Mafic to Felsic Marks the Onset of Plate Tectonics." Science 351.6271 (2016): 372-75. Web. 13 Nov. 2016. 2.4 billion years ago -Great Oxidation -Cyanobacteria: first real photosynthesis -Drastically changes the composition of the atmosphere: less CH4, far more O2 -First mass extinction -Leads to the first snowball Earth (~2.2 billion years ago) Sessions, Alex L., David M. Doughty, Paula V. Welander, Roger E. Summons, and Dianne K. Newman. "The Continuing Puzzle of the Great Oxidation Event." Current Biology 19.14 (2009): R567-574. ScienceDirect. Web. 13 Nov. 2016. The Definition of Life on Earth Criteria of Life ● ● ● ● ● ● ● Homeostasis (resistance to change) Metabolism (taking in energy) Organization (one or more cells) Reproduction Response to stimuli Growth (increase in size, not just accumulation) Adaptation (needed in process of evolution) Exceptions to Definition The large gray area in the definition of life: Viruses When in contact with host: ■ Active ■ Can reproduce when host is “infected” ■ Reacts to environment ■ Behaves like a living organism Without contact with host: ■ Dormant, inactive ■ Cannot reproduce or replicate itself ■ Static organic particle (these are known as Virions) ■ No internal biological activities Crystals Exhibit many of the characteristics of living things: ● ● ● ● Growth Take in energy by chemicals Response to stimuli “Adapt” to environment But it doesn’t have a nervous system and can’t reproduce Its growth is accumulative, not increase in different parts of organism Why life on Earth is unique Life depends on the characteristics of Earth ● ● Orbits the sun (a star of a certain size) Orbits at a certain distance (and is almost circular in orbit) ○ ○ ● ● This determines the temperature (along with the atmosphere on Earth) Covered in liquid water (needed for life) Within the considered “habitable zone” around the sun Temperature is within a certain range for living ○ Spin of Earth contributes to constant temperature Life outside of earth (what we look for) We look for another earth Same characteristics of earth that could support human life. Water and atmospheres Habitable zones around a star (one similiar to the sun) But what if life outside of Earth looked completely different? Kepler-186f ■ ■ ■ ■ ■ (one of five planets in system) Similar size to Earth Within habitable zone of Kepler-186 System Composition is most likely to be rocky 490 light years away Orbit of about 130 days around red dwarf star We are looking for earth-like planets which means earth-like life. Microbiologist “Venkat” Experimenting with life in space (fungi and bacteria) and how space affects life Samples sent on SpaceX Dragon Capsule with two microbial tests Microgravity effects on tiny organisms Detected radiation-resistance bacteria Work shows ● ● ● Effects on astronauts in space (health) New compounds for radiation therapy and cancer treatments what kinds of life can survive in space and on planets with different compositions and atmospheres Abiogenisis Inorganic Matter -----------> Living Things What Does Life Need? Energy Water Safe Environment Variety of Chemicals Energy Activation Energy Gibbs Free Energy Equation Ex. Micelle ∆G=∆H-T∆S Liquid Water Great Solvent -Acts as Acid and Base -Holds ions Ex. Miller-Urey Experiment Safe Environment Protection from radiation Protection from collisions Ex. Life by land and by sea Important Chemicals Meteorites Rocks and Minerals Iron How to Find the Origins of Life Bottom Up or Top Down Approach - Place chemicals and conditions to create life (Miller-Urey) - Look at life and work backwards (Craig Venter) Metabolism Breaking and building molecular bonds Using energy of one reaction to power another reaction Ex. Iron and Clay provide surfaces for the reactions to take place Replication: Finding LUCA 355 genes common to all life on earth Genes produce a CO2 and N2 fixing with H2 dependant and thermophilic. Metabolism Vs. Replication Modern Chicken and Egg Most people believe that metabolism was first Provides and environment for replication to occur Ex. http://biochemical-pathways.com/#/map/1 So What Happened? What Do We Know? Earth forms from basic chemical compounds Earth cools, allowing for deep vent formation T=100-150C Basic Elements form chemical monomers ex. Amino Acids etc. Chemicals attach to surface creating specific environments These environments localize metabolic processes Metabolic process provide environment for RNA replication All processes contained in cell wall The Theory of Evolution What is it? A quick summary The theory of evolution by natural selection is the process in which organisms change over time as a result of changes in heritable physical, or behavioral traits. All organisms are thought to have a common ancestor as well! “It is not the strongest of the species that survive, nor the most intelligent, but the one more responsive to change.” - Charles Darwin… Who is he? Charles Darwin (1809-1882) Went to the galapagos, and saw something strange… Various species of finches that varied from island to island WHY!? Wrote his book The Origin of Species when a majority of the world believed in some form of “Creator”. Natural selection and adaptations. Natural selection is essentially an organism's ability to survive in various conditions, and to successfully reproduce. Adaptations are when an organism changes to be better suited to its environment usually driven by mutations. The craziest example of this, are whales! Let’s draw an example Evolution Telephone So for those of you that couldn't follow my drawing, we have a classroom activity to try out. End Evolution today. Peppered moth story The History of Life’s Evolution Brett By the end of my section you should be able to ● ● ● ● ● Understand the basic timeline of life on Earth Understand the basic timeline of the geology of Earth Know why extinctions were important for biodiversity Evaluate what your favorite looking animal was of all of history. Be able to find one TRULY cool fact per slide Major Events overview ● ● ● ● ● ● ● ● ● ● ● ● Life Started (3.7 BYA) Photosynthesis (3..7-3.4 BYA) Plate tectonics (3 BYA) Oxygen Atmosphere (2.4-1.6) BYA) Multicellular Life (2 BYA) Endosymbiosis (2-1 BYA) First Sex (1.2 BYA) Shell animals (535 MYA) Plants on Land (465 MYA) Mass Extinction #1 (460 MYA) Sea to land animals (375 MYA) Devonian Extinction (375 MYA) ● ● ● ● ● ● ● ● ● ● Reptiles (320 MYA) Pangea (300 MYA) Permian Extinction(252 MYA) Mammals (220 MYA) Triassic Extinction (201 MYA) Feathered Birds (160 MYA) Flowers and Grains (130 MYA) Death of Dinosaurs (65 MYA) C4 Photosynthesis (32 MYA) First Hominins (13 MYA) Life starts (3.5 Billion Years) ● 3.5 billion years old ○ Confirmed by fossils ● Stromatolites (microorganism mats) ○ Energy from sun ○ In the water ○ Rocks and matter found in crust NO plate tectonics at this point. ● ● How old is this? ○ 3.5 BYA-.201 BYA ■ ■ =3.29 billion years before ‘Titanic Dinosaurs Stack of 1 billion dollars ● 67.9 miles Photosynthesis-ish (3.7-3.4 BYA) ● ● ● No modern photosynthesis Just used the sun to reduce (gain electrons) and store energy in bonds ○ Could have been iron, or anything to conduct redox reaction ○ Thought to be hydrogen and sulfur, NOT water 1937, Robert Hill discovered plants can 4 Fe3++2H2O → 4Fe2+ + O2 + 4H+ How do we know? ○ There was life, but there was no O2 deposition clues. ○ Deep sea vents hold bacteria that live off of sulphur and hydrogen reduction Plate Tectonics!! (3 BYA) ● Puts nitrogen into the atmosphere! ○ ● ● Evidence? Recycling of rocks Not totally for certain on time. Soaks up CO2 ● Coolest one: Paleomagnetism ○ ○ ○ ● Why is Nitrogen important? ○ ○ ○ DNA RNA Proteins and peptide bonds ● Magnetite in lava rocks point north when cooled. All basalt doesn’t point in the same direction! Poles are assumed to stay at axis The Great Oxidation Event (2.4 BYA) ● Bacteria began to photosynthesize! ○ ○ ● Again? (Oceans were full!) CO2 and H2O this time Made “Snowball Earth” ○ Just enough crust showing to continue life ○ Caused by O2 stripping Methane from atmosphere ● How do we know? ○ Iron Oxide precipitation in oceans ○ Means oxygen saturated water, and began staying in atmosphere Endosymbiosis (2-1 BYA) ● What is it? ○ Cells eat other cells! Like eating a chef and they are always being there to cook! ● What is the evidence? ○ ● Mitochondrial DNA is more closely related to bacteria than parent cell! Not readily accepted until 1960’s! ● Why is this important? ○ ○ ○ Allows ‘us’ to make ATP Allows plants to make sugars Helped life become complicated! Multicellular Life (2.1 BYA) ● Cells of same code become organized ● Evidence ○ ● Why is this important? ○ ○ ○ Bigger container More organization Allows resilience! ○ ○ Shale found in Gabon of ‘centimeter-sized structures interpreted as organized and spatially discrete populations of colonial organisms living in an oxygenated marine ecosystem. Extremely rare in the fact that all other rocks of this age “ have experienced thermal overprinting from burial diagenesis and metamorphism, [these samples] have not.” Last evidence was 575 million years ago First Sex (565 MYA) ● It was very special? Nah... ○ ● ● They didn’t catch feelings Why is it important? ○ ○ ○ Sponge like creatures in ancient oceans. Creates increased rate of evolution Genetic variety for multicellular Red Queen hypothesis ■ ● “I don’t wanna shmang, you and your whole family sick all the time” My theory: Mutation in DNA synthesis and the rest might work? ● Evidence? ○ ○ F. dorothea in 2005 (see left) in Australia (back at it again with Earth’s History) Ordovician Extinction (444 MYA) ● What caused the extinction? ○ ○ Ice age from CO2 being sucked by new rocks (remember tectonics!?!) ● What was there: Sea Creatures ○ ○ ○ ● Graptolites ■ Filter feeders Trilobites Conodonts ■ Toothy invertebrates Left room for FISH! The Great Dying aka Permian Extinction (252 MYA) ● What caused it? ○ ○ ○ ● Volcanos created Greenhouse effect Methane released by microbes in response Oceans acidified What was there? ○ ○ ○ Marine invertebrates Ferns Synapsids (mammal-like reptiles) 96% of ocean life died ○ ● ● 300 million years wasted 50% land life died ● Who filled the gap? ○ ○ Dinosaurs! Seed plants! ■ conifers Triassic Extinction (200 MYA) ● What caused it? ○ ● Debated ■ Pangea rifting led to warming ■ Methane release from mild warming ■ Asteroid Who was there? ○ ○ ○ ● Dinosaurs Marine reptiles brachiopods Who filled the gap? ○ More dinosaurs! (Jurassic Park) Cretaceous Extinction (65 MYA) ● What caused it? ○ ○ ● Most likely Asteroids ■ Made earth real dark ■ No more photos please! Could also be more plate tect Who went extinct? ○ ○ ○ ○ ● Dinosaurs Marine invertebrates Crocodiles Ancestors of modern birds Who filled the Gap? ○ ○ LIttle mammals Plants of today! Alternative Life Forms Extremophiles ● Defined as organisms that thrive under extreme conditions ○ ● ● Microbes thrive in conditions that would terminate humans in seconds The term is generally used to describe prokaryotes but can also be used to describe bacteria and archaea Most extremophiles are microbes Anaerobic Organisms ● ● An organism that does not require oxygen for growth In some cases, oxygen is actually toxic to the organism ○ ● Obligate anaerobes Anaerobic organisms do not produce energy from carbon dioxide, rather, they metabolize inorganic compounds Prokaryotes ● Do not require free oxygen to sustain themselves ○ ● ● Not harmed by free oxygen in their environment Single celled organisms Lacking membrane bound organelles ○ Some have chloroplasts and can respire via photosynthesis Cyanobacteria ● ● ● ● Single celled Survive through photosynthesis Generate about 16x more energy than anaerobic organisms Capable of surviving in extremely harsh conditions The Oxygenation Event ● ● Responsible for the evolution of aerobic respiration and the catalyst for the evolution of stable and successful life on Earth Proves that the study of extremophiles is important in the search for extraterrestrial life Snowball Snowball Earth Earth ● In a relatively short time period: ○ Oxygen levels skyrocketed, causing the oceans to be inhabitable to some anaerobic organisms ○ The methane and CO2 rich atmosphere was dominated by oxygen, causing temperatures to drop due to a lack of greenhouse gasses ○ Many scientists theorize that the severity of this event is what caused cellular differentiation Antarctica ● ● ● Excellent representation of earth during its snowball and ice age periods Organisms that survive here are not necessarily anaerobic, but can survive extremely low temperatures and a relatively high pH balance Colwellia is a type of deep sea anaerobic bacteria that is found in ice samples from Antarctica ○ Similar environments and organisms may be found on other planets Yellowstone ● Thermophiles ○ Metabolic processes ■ Photosynthesis ● Occurs in plants, algae, and cyanobacteria ■ Fermentation ● Extremely inefficient compared to aerobic cellular respiration ● Oxygen is the most efficient electron acceptor of the ETC due to its high electronegativity ○ Process of cellular respiration is called oxidative phosphorylation and is about 16 times more efficient than fermentation Hydrothermal Vents ● ● Form at locations where seawater meets magma Extremely harsh environment ○ Ejected fluids are full of ○ elements such as iron, calcium, and silicon Water reaches up to 700℉ ○ Home to numerous extremophiles