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Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Origin of Life Chapter 4 pages 67 -87.

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Presentation on theme: "Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Origin of Life Chapter 4 pages 67 -87."— Presentation transcript:

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2 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Origin of Life Chapter 4 pages

3 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Question? zWhere does life come from? zThe ancient Greeks first asked this question. zThey devised two possible answers:

4 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Abiogenesis zBelief that living things could arise from nonliving materials. zAlso known as “spontaneous generation” zMany examples: yMaggots are formed from old meat ymice can form from dirty shirts, water, and wheat hidden in a closet yfrogs come from mud

5 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Active Principle zAristotle proposed that an active principle brought life to nonliving materials. yHumans get it from parents yMaggots get it from meat yFrogs get it from mud

6 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Biogenesis zBelief that living things could only come from other living things. zFrancisco Redi, a 17th century scientist tried to prove this

7 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Francisco Redi Maggots from flies.

8 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Redi’s Hypothesis zMaggots on meat come from another living thing. zRedi noticed flies around decaying meat, so he proposed that maggots were related to the flies

9 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Redi’s Experiment Meat in open jar.  Maggots appear in jar.  Meat and maggots gone.  

10 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Conclusion of Time zMeat became maggots which left to find food. zTo prove maggots were flies he repeated experiment by covering one jar after maggots appeared.

11 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Controlled Experiment  Control  Covered   Flies  appeared

12 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Redi’s Conclusion zMaggots are immature flies that use meat as food. zHe now proves that flies leave something on meat to form maggots.

13 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Another Experiment

14 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Biogenesis accepted zRedi’s work convinced scientists that biogenesis was true. yLeeuwenhoek discovers “animalicules” in water with his simple microscope yAbiogenesis was in vogue again

15 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Needham Vs. Spallanzani Broth becomes microbes.

16 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Needham zBelieved in abiogenesis: Êboiled broth to kill microbes Ëcorked flasks to stop life in Ìcork allowed air the “vital principle” in

17 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Needham Experiment fresh broth  boiled broth  corked broth  its alive 

18 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Spallanzani zBelieved in biogenesis: Êdidn’t boil long enough to kill Ëcork too porous; new life in

19 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Spallanzani Experiment short boil  cork  its alive 

20 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Spallanzani Experiment short boil  melted  its alive 

21 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Spallanzani Experiment long boil  melted  not alive 

22 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Conclusion zSome of Spallanzani’s flasks are still free of life. yAbiogenesis believers said he did not let “vital principle” in yspores enter with air

23 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Louis Pasteur zLate 1800’s abiogenesis disproved allowing air in keeping spores out. y“Swan Necked Flask” curves let air through yspores. boiled  no life 

24 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Swan Necked Flask zTilting fluid into neck proved spores were caught. no life  life 

25 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Biogenesis true zDoes all life have a common ancestor? zWhere did very first life originate? zThree hypotheses were considered:

26 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001  Supernatural zAll powerful God created life yfound in all cultures’ mythology yno way to prove or disprove ynot scientific xcreationism, scientific creationism, intelligent design

27 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001  Exobiological View zLife, like matter & energy always existed. yIt arrived from outer space as spores yPlausible but how did life start out there. xKISS Principle and Occam’s Razor If a simpler explanation possible go with it before you accept a more complicated explanation

28 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001  Chemosynthesis zLife developed on Earth by natural processes. yPrimitive Earth has all materials yPrimitive Earth has proper conditions. yMost “scientific” explanation

29 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Oparin Haldane Hypothesis zDeveloped independently by two biochemists: yJohnHaldane yJohn Haldane - England yAlexanderOparin yAlexander Oparin - Russia BIG BANG zHow life began after the BIG BANG.

30 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Known observations ¶Life composed of four (4) Major Classes of Complex Chemicals: 3proteins 3lipids 3carbohydrates 3nucleicacids 3nucleic acids

31 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 More observations BUILDING BLOCKS ·Complex chemicals composed of simpler BUILDING BLOCKS: 3proteins 3proteins - amino acids 3lipids 3lipids - fatty acids & glycerol 3carbohydrates 3carbohydrates - sugars 3nucleicacid 3nucleic acid – nucleotides ¸Building blocks are composed of common elements: C H O N 3amino acids - C H O N C H O 3fatty acids & glycerol - C H O C H O 3sugars - C H O C H O N P 3nucleotides - C H O N P

32 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 More observations ¹Universe began with a gigantic explosion that: 3made simple gases 3gases condense and freeze 3planets form ºPrimitiveatmosphere ºPrimitive Earth atmosphere different from today’s: 3ammonia 3ammonia - NH 3  3methane 3methane - CH 4  3watervapor 3water vapor - H 2 O 

33 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 More observations »Abundantenergy »Abundant energy combines gases: 3Heat 3Heat - from molten core & lava 3Steam 3Steam - water contact with lava 3Electrical 3Electrical - lightning in storms 3Radiant 3Radiant - UV & IR radiation of sun

34 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Chemical Evolution ¬Energycause chemicalbonds ¬Energy from heat, light, electricity, and radioactivity cause new chemical bonds to form; ­Stableremain ­Stable bonds remain; ®Unstablebreakdown ®Unstable bonds break down; ¯Randombondsformbuilding blocks ¯Random formation of bonds in gases form the chemical building blocks; Hot ThinSoup °Building blocks condense and rain into the oceans forming a Hot Thin Soup; ±HotThinSoupsugarsfattyacids glycerolaminoacidsprimitivenucleotides ±Hot Thin Soup - contains randomly formed sugars, fatty acids, glycerol, amino acids, and primitive nucleotides; energyrandomlyforms macromolecules ²Heating and cooling with night and day more condensation and bonding; Continued input of energy randomly forms macromolecules from the building blocks; Hot ThickSoup ³The macromolecules condense into the oceans forming the Hot Thick Soup;

35 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Cellular Evolution HotThickSoupproteinslipidsnucleic acids carbohydrates À Hot Thick Soup - contains proteins, lipids, nucleic acids, and carbohydrates; coacervates proteinoids ÁMacromolecules aggregate to form cell-like clusters called coacervates or proteinoids; heterotrophs “precells” use macromolecules in oceans as food, forming the first heterotrophs; fermentationcarbondioxide ÃThey release free energy by fermentation forming carbon dioxide (CO 2 ) in the atmosphere; ÄCO 2 in atmosphere slows random synthesis of molecules; ÅFood in the oceans becomes scarce; chlorophyll ÆCell clusters develop pigments like chlorophyll, that captures light photosynthesisautotrophs ÇCell clusters - capture light - make food -photosynthesis - autotrophs; ÈCell clusters add free oxygen (O 2 ) to the atmosphere ÉAtmospheric O 2 reduces mutating UV light penetration respiratory heterotrophs Scarcity of free sugar and presence of O 2 causes appearance of respiratory heterotrophs.

36 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Experimental Evidence Chapter 4 pages 73-80

37 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Urey Miller Experiment zlaboratory apparatus simulated conditions for hot thin / hot thick soup. Àclosed glass system, filled with water Áammonia and methane gases were pumped in Âwater heated, electrodes in gases gave sparks Ãultraviolet and infrared lamps Äcondenser used to cool gases Åruns for a week.

38 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Urey Miller Apparatus  water heater  NH 3 CH 4   light electrode sparks  condenser   cold  warm

39 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Conclusion zScientists removed some fluid from the water and found: ysimple amino acids ysimple sugars

40 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Fox Experiment zFox took material similar to those in Urey’s results yaltered the pH as proposed in “puddle” of soup ycoacervate aggregates were formed

41 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Woese Hypothesis zProposed that “pre-cells” formed as droplets on dust entering the atmosphere

42 Updated Nov 11, 2005 Created by C. Ippolito Dec. 9, 2001 Cairns-Smith Hypothesis zOne problem not solved is reproduction zCairns-Smith proposes that naked crystals of clay can replicate and were the first to store information


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