Origin in 4 overlapping stages:

1. nucleotides and AA's produced prior to existence of cells 2. nucelotides and AA's became polymerized to form DNA, RNA and proteins 3. polymers became enclosed in membranes 4. polymers enclosed in membranes acquired cellular properties

stage 1: Reducing atmosphere hypothesis

-atmosphere rich in H2O, H2, CH4, NH3 and little O2 -formed precursors, AA's, sugars and nitrogenous bases -1953, Miller-Urey experiment produced AA's w/ H20, H2, CH4, NH3 w/ simulated lightning -first scientifc attempt to understand origins of l

stage 1: Extraterrestrial Hypothesis

-meteorites brought organic carbon to earth along with AA's and nucleic acids bases (called carbonaceous chondrites) -opponents to this argue that most of this matter would have been destroyed in the intense heat and collision of entry

stage 1: deep sea vent hypothesis

- 300 ° C H2S (Hydrogen sulfide) - archae reduced the H2S to S through chemiosynthesis - biological important molecules formed in the temp. gradient between vent water and ocean water

Stage 2: formation of organic polymers

- experimentally, prebiotic synthesis of polymers not possible in aqueous solutions because hydrolysis competes with the polymerization -formation of nucleic acid polymers and polypeptides on a clay surface

Stage 3: formation of boundaries - protobiont

aggregate of prebiotically produced molecules and macromol. that acquired a boundary, maybe lipid bilayer, that allowed maintaining int enviro unique to ext enviro. -also capable of self-replication -polymers inside held info. and had enzymatic func.

spontaneously formed from the association of charged polymers enzymes trapped inside can perform metabolic functions

vessicles surrounded by a lipid layer clay can catalyze their formation can grow and divide which is primitive self-replication can enclose RNA

3 key RNA functions: - stores info - self-replication - enzymatic functions (ribozyme) DNA and Proteins do NOT have all 3

chemical in mixture of different chemicals has special properties or advantages that cause it to increase in # compared to other chemicals

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Bio - test 1

Question	Answer
The Earth is ? years old	4.55 billion years
life emerged ? years ago	4-3.5 billion years
Origin in 4 overlapping stages:	1. nucleotides and AA's produced prior to existence of cells 2. nucelotides and AA's became polymerized to form DNA, RNA and proteins 3. polymers became enclosed in membranes 4. polymers enclosed in membranes acquired cellular properties
stage 1: Reducing atmosphere hypothesis	-atmosphere rich in H2O, H2, CH4, NH3 and little O2 -formed precursors, AA's, sugars and nitrogenous bases -1953, Miller-Urey experiment produced AA's w/ H20, H2, CH4, NH3 w/ simulated lightning -first scientifc attempt to understand origins of l
stage 1: Extraterrestrial Hypothesis	-meteorites brought organic carbon to earth along with AA's and nucleic acids bases (called carbonaceous chondrites) -opponents to this argue that most of this matter would have been destroyed in the intense heat and collision of entry
stage 1: deep sea vent hypothesis	- 300 ° C H2S (Hydrogen sulfide) - archae reduced the H2S to S through chemiosynthesis - biological important molecules formed in the temp. gradient between vent water and ocean water
Stage 2: formation of organic polymers	- experimentally, prebiotic synthesis of polymers not possible in aqueous solutions because hydrolysis competes with the polymerization -formation of nucleic acid polymers and polypeptides on a clay surface
Stage 3: formation of boundaries - protobiont	aggregate of prebiotically produced molecules and macromol. that acquired a boundary, maybe lipid bilayer, that allowed maintaining int enviro unique to ext enviro. -also capable of self-replication -polymers inside held info. and had enzymatic func.
coacervates	spontaneously formed from the association of charged polymers enzymes trapped inside can perform metabolic functions
liposomes	vessicles surrounded by a lipid layer clay can catalyze their formation can grow and divide which is primitive self-replication can enclose RNA
Stage 4: A RNA World	3 key RNA functions: - stores info - self-replication - enzymatic functions (ribozyme) DNA and Proteins do NOT have all 3
chemical selection	chemical in mixture of different chemicals has special properties or advantages that cause it to increase in # compared to other chemicals

Created by: 1423555193

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