SIO40lecture4

SIO40lecture4 - SIO 40 Life and Climate on Earth Lecture 4...

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SIO 40 – Life and Climate on Earth Lecture 4 - Origins of Life Friday October 1, 2010
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Lecture Outline - Conditions required for the development of life - Basic components of life - Pre-biotic synthesis of amino acids - "RNA world" - Roll of mineral phases - Tree of Life
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Orbital diagrams comparing the Gliese 581 system to our own solar system.
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Temperature on the planet depends on the : light/heat it receives from a star (Sun). content of green house gases in the atmosphere reflectivity of its surface (albedo) Today the earth reflects back about 33% of the light that it receives from the Sun. Without an atmosphere, this would result in a planet with a surface temperature of –20ºC which does not allow for liquid water. Greenhouse gases in the atmosphere enable Earth to maintain a significantly higher surface temperature. What We Need for Life to Begin – Not too Hot, Not too Cold
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Lack of oxygen: Reducing atmosphere relative to today – CO 2 , N 2 , H 2 O, (H 2 ? NH 3 ? CH 4 ?), no O 2 Organic compounds contain reduced carbon. These compounds would have been very unstable in an atmosphere with oxygen. What We Need for Life to Begin – The Right Chemical Conditions surface of early ocean? hydrothermal vent? Where did the right chemical conditions develop?
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Two functions are essential: (1) the ability to replicate and (2) the capacity to undergo gradual change via mutation and natural selection. Commonalities amongst organisms; Consist of similar organic (carbon-rich) compounds All organisms access the same 20 amino acids All organisms carry their genetic information in nucleic acids – DNA and RNA. RNA carries the code for protein synthesis. Three bases encode for one amino acid. Proteins (polymers of amino acids) direct the reactions required for self-perpetuation. What is Life Today? Cell division of microscopic freshwater green algae Microscopy UK all material © Wim van Egmond
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Early Speculations About the Origin of Life Darwin, Oparin and Haldane – Primordial Soup Theory
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http://www.bact.wisc.edu/Microtextbook/ Amino Acids, the building blocks of proteins Basic amino acid structure
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This note was uploaded on 05/02/2011 for the course SIO 40 taught by Professor Barbeau,k during the Fall '08 term at UCSD.

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SIO40lecture4 - SIO 40 Life and Climate on Earth Lecture 4...

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