Download Origins of Life PPT - Leon County Schools

ORIGINS OF LIFE
EARLY IDEAS
I. SPONTANEOUS GENERATION:(NOT REJECTED UNTIL THE MID 1800S)
-LIFE ARISES FROM NON LIVING MATERIAL
-FRANCESCO REDI, AN ITALIAN SCIENTIST, IN 1668 TESTED THE IDEA THAT FLIES
AROSE SPONTANEOUSLY FROM ROTTING MEAT. (SCIENTIFIC COMMUNITY NOT
ALL CONVINCED)
EARLY IDEAS
II. THEORY OF BIOGENESIS:
• LIVING THINGS CAN ONLY PRODUCE LIVING THINGS
• LOUIS PASTEUR DESIGNED AN EXPERIMENT TO SHOW THAT BIOGENESIS
WAS TRUE EVEN FOR MICROORGANISMS
MODERN IDEAS: MILLER-UREY EXPERIMENT
SIMPLE MOLECULE FORMATION:
• 1943 STANLEY MILLER AND HAROLD UREY:
MILLER-UREY EXPERIMENT
ADD THE PICTURE TO YOUR NOTES AND
LIST THE STEPS IN THEIR EXPERIMENT
(WATCH VIDEO)MILLER UREY VIDEO
MODERN IDEAS: MILLER-UREY EXPERIMENT
PURPOSE: DEMONSTRATE THE FORMATION OF SIMPLE ORGANIC
MOLECULES FROM INORGANIC COMPOUNDS
RESULTS: EXPERIMENT PRODUCED SEVERAL AMINO ACIDSSUGGESTED THAT EARLY EARTH HAD SUBSTANCES THAT COULD
PRODUCE ORGANIC COMPOUNDS AND THEN LIVING THINGS.
MODERN IDEAS
• ONCE AMINO ACIDS WERE FORMED, PROTEINS ARE NEEDED FOR LIFESCIENTISTS THINK CLAY PARTICLES COULD HOLD AA TOGETHER TO FORM
PROTEINS
• EARLY GENETIC MATERIAL-RNA
• SCIENTISTS ARE WORKING TO
DISCOVER HOW ORGANIC MOLECULES
BECAME CELLS
CELLULAR EVOLUTION
• FIRST CELLS WERE PROBABLY PROKARYOTIC
• ARCHAEA (MODERN PROKARYOTES) ARE PROBABLY THE CLOSEST
RELATIVES OF MODERN CELLS
• CYANOBACTERIA-PRIMITIVE PROKARYOTES-AUTOTROPHS-PRODUCED
OXYGEN TO FORM OZONE LAYER-ALTERS CONDITIONS ON EARTH FOR
EUKARYOTIC CELLS TO SURVIVE
ENDOSYMBIONT THEORY
• 1966, LYNN MARGULIS, ANCESTORS OF EUKARYOTIC CELLS LIVED IN
ASSOCIATION WITH PROKARYOTIC CELLS-POSSIBLY INSIDE-DEVELOPED
MUTUALLY BENEFICIAL SYMBIOTIC RELATIONSHIP
• EVIDENCE:
• MITOCHONDRIA AND CHLOROPLASTS HAVE THEIR OWN DNA AND
RIBOSOMES SIMILAR TO PROKARYOTIC RIBOSOMES
• MITOCHONDRIA AND CHLOROPLASTS REPRODUCE BY FISSION (LIKE
PROKARYOTIC CELLS)
VIEW: ENDOSYMBIONT THEORY-CONCEPTS IN MOTION (ONLINE TEXT)
ENDOSYMBIONT THEORY