BIO 105 1st Edition Lecture 19Past Lecture (18)Early Earth - Not enough oxygen in atmosphere for the living.- There was strong radiation, no ozone. - No aspects for living, and no promise.Two theories of origin of life on Earth1. Life building molecules arose outside of Earth through pre-biotic chemical evolution – exogenesis- Supporting evidence o Organic matter (building blocks) throughout galaxies and Universe.o Some meteorites carry molecules of life.- Challenges o It is a long inter-planetary/galactic trip by living organism possibleo No known life outside Earth- There are possibility primitive meteorites and comets brought water to early Earth.(Through impact)- Life building compounds on early Earth may have had cosmic origins.2. Life arose on early Earth through pre-biotic chemical evolution – abiogenesis- Organic soup/primordial soup-No one knows where the origin of life began.-“Degassing” brought a lot of energy, and the Earth need energy for molecules to form. Miller-Urey Experiment (1950’s)- Formed molecules in experiment by mimicking early Earth.- Found building blocks of life- Multitudes of organic molecules form readily.- Re-evaluated many times since early atmosphere was different that what was firstthought.- Chemical evolution still supported by abundance. Complex macromolecules form  protocells (first cell)  more complex cells- Conditions on early Earth were suitable for formations of carbon rich molecules –from which life evolved.- Very primitive life by 3.8 billion years ago.Protocells – early formation of cells- No one has synthesized a living cell.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- The earliest life consists of prokaryotes, which lived in an oxygen-free environment, 3.8billion years ago.- Infant life and early Earth began to evolve together.Eukaryotic –all need oxygen- All multicellular life.- Varies in size- DNA strandProkaryotic (bacteria)- Much smaller- No nucleus - Circular DNA- No-membrane bound organelles- Abundant todayPhotosynthesis (2.8 billion years ago) evolved. (Some cells develop capacity to deal with Ozone)- Oxygen later increases in the atmosphere.- IT IS IMPORTANT – greatest pollution in early history of the Earth. 6CO2 + 6H2O ------> C6H12O6 + 6O2- Life formed intimate relationships with sun.- Superpower creates food from sunlight within its own body.*Photosynthesis develops in prokaryotes (3.5 -3 billion years ago)- Prototroph = eat light - Sustains all eukaryotes life, a keystone moment.Oxygen Revolution begins… very slowlyGreat oxygen event (GEO) -2.4 billion years ago- Atmospheric and ocean shifts from abiotic to biotic regulationo Regulation by life on earth.Origin of Eukaryotes - In Endsymbiotic Hypothesis (beneficial) for origin of mitochondria (powerhousegenerators of cell) and Chloroplasts (energy suppliers)- It states that some of the organelles in today’s eukaryotic cells were once prokaryoticmicrobes. - Chloroplasts are descendants of photosynthetic prokaryotes.- Giant leap in evolution, it makes complex life possible. - Cooperation, not competition- Eukaryotes merged 2 billion years ago.Universal tree of life- Not all unicellular life is prokaryotic- All evidence supports the single origin.- Atmospheric oxygen increases- Stratospheric ozone forms, and has protected life for 450 million years.Present Level of Gas in TroposphereNitrogen – 75%Oxygen – 21%Argon - .93%Carbon Dioxide -.03%Traces of water, methane, etc.Current Lecture (19)Atmospheric Appreciation-Oxygen level – 21%-Stratospheric Ozone – has protected life on Earth for 450 million years and be the reason lifemoved from water to land.-The ozone hole: allows more sun radiation onto land.-Global warming – greenhouse gasses in the troposphere where we live. There are two levels in atmosphere with ozone. (Good up high, bad down low)- Stratosphere ozone protects life from ultraviolet rays.- Troposphere ozone is an pollutant and greenhouse gas.Troposphere Troubles- Greenhouse gas ≠Global warming- Weather ≠Climate Greenhouse Gases = 1%- Cary in heat tradability - All have risen drastically in last decade.- CFC’s  human-made in troposphere acts as greenhouse gases.Global weirding- pushing the extremes of weather.Keeling curve – dramatic increase in carbon dioxide. Plants don’t take up carbon dioxide in fall.Atmosphere change is due to photosynthesis. -The more greenhouse gases, the higher global temperature. - 280 ppm – pre-industrial carbon dioxide levels. - 350 ppm – (1990) This is safe atmospheric level. This won’t alter any human activity.- 400 ppm – today’s level.- 550 ppm – 2015 projection- 1960: when we first found out excess carbon dioxide is an issue. Facts:- Average temperatures have climbed 1.5 degrees F since 1800- Rate of warming is increasing - now more than double.- Globally, ice is rapidly disappearing- Carol reed bleaching widespread (warming oceans)- Sea level rising- Upsurge in extreme weather events.- The sun is currently in a period of abnormal law solar activity. Evidence?1880- First started testing temperatures with thermometer.How do we know about past climate?- Paleoclimate evidence - We can read tree ringso Different type of elements found in rings themselves- Corals – read past climates- Ice cores (Mesozoic era – no