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25 Cards in this Set

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Spontaneous Generation
a beginning genesis w/o life Ex. life has risen from dead organic material: Rotten meat-> flies
Swan neck flask experiment disproves spon.generation
shows that organism don't just spontaneously arise but come into existed as a decendent of similar organisms
Darwin's thought
Life arose in warm phosphate rich ponds
In 1920s, A.I.Oparin and J.B.S. Haldane
come up with first serious proposals on the conditions necessary for life based on sound biology and Geol. info.
J.B.S. Haldane & Opirin
postulated/assumed the conditions on earth necessary for the synthesis of organic monomers
basic building block of life from inorganic precursors
(Abiotic synthesis of organic monomers from inorganic precursors)
*Haldane & Oparin Conditions
1)reducing atmosphere
-containing molecules having less Oxygen than hydrogen
2)Lots of UV
3)Primidial gases: CH4,NH3,H2
Oxidizing atmosphere
(lots of O2)
It's not conducive(favorable) for the spontaneous synthesis of complex molecules coz O2 will extract electron
Degassing of the earth's interior
*In 1953 Harold Urey& Stanley Miller set up an experiment to examine Haldane-Oparin conditions
1)boil water(ocean)
2)reducing atm.(CH4,NH3,H2)
3)Tungstenelectrodes dischanging > lightning
then color change from clear to murky, found four amino acids,urea,simple fatty acids
Abiotic Synthesis of Polymers
making macromolecules by dehydration synthesis
1)monomers 2)polymers
Sidney Fox
drop monomers on the hot clay(ocean basin), then water vaporating->metalic ion attract electron->bond forms(proteinoids)
Abiotically produced polypeptides
Aggregates of abiotically produced molecules.
Antecedent of the first true cells
3 Types of Protobionts
tiny droplet codes by a selective permeable membrane.
Ex.Protenoids + cool water >microsphere>unstable size>
2 daughter cells "Self Replication"
take some phospholipids+H2O->
Phospholipid bilayer.
Liposome can give birth to smaller one
Polypeptide+Nucleic acid+Polysaccharide and shake them up
Origin of genetic material
is DNA
first gene
RNA (single-Stranded)
RNA is autocatalytic:being able to replicate itself with enzyme
Pieces of RNA that act like enzyme. " Ribosomes catalyse the synthesis of new RNA"
Before they were proteins enzymes or DNA
RNA is capable of cell replication
DNA replaced RNA
Coz. DNA is double stranded(more stable)
Anaerobic world or
Organic soup(early ocean)
First organism were primary heterotroph(can't make their own food)
They were a great selective advantage if they could make their own
Ex. Cyanobacteria -make own food by photosyn. give lots of O2 to atmosphere
-> Oxidizing atm.