Origin Of Life Flashcards
Steps in metabolism
Nutrient uptake
Nutrient processing
Waste elimination
Generative processes
Growth and reproduction (replication)
Responsive processes
Individual adaption
Immediate responses to environment
Population evolution
Control processes
Coordination
regulation
Structural organization
Cellular level
Organismal level
What was the first idea of origin or life and proposed by who
Spontaneous generation by Aristotle. “Living organism arise spontaneously from non-living matter”
Maggots formed from dead meat, lice product of sweat
What is biogenesis
Life can only originate from pre-existing life
Three things needed for life
Energy source
Raw materials
Suitable environment
What were the conditions in early earth
Extremely high temps
Diff atmosphere (water vap, nitrogen, co2, methane, ammonia, hydrogen, hydrogen sulfide were all reducing)
No liquid water
Little oxygen
As earth cooled water vapour condensed, hydrogen escaped
What were the energy sources on early earth
Sun (light, UV)
Volcanic eruptions
Lightning
What materials present on early earth
C H N O P S
extraterrestrial sources
Scientists believe that first life form was made of RNA cause
RNA is self replicating molecule
Support for extraterrestrial sources on earth
Carbonaceous chondrites e.g. murchison meteorite contained disomer amino acids
ALH 84001 meteorite - believed to have martian bacteria
Describe the origin of life on earth by chemical evolution
Stage 1 - Abiotic synthesis of monomers (aka simple molecules)
Stage 2 - Formation of polymers ( putting simple monomers together to make smtg more complex)
Stage 3 - Packaging of polymers into protocols (packing into 1st cells)
Stage 4 - Self replication t
What does meros and pro to and A mean
Meros - part
Proto - first
A - absence
Descibe oparin’s hypothesis
Stage 1 - Spontaneous formation of monomers
Believed early earth had reducing atmosphere, and if combined with source of energy, simple molecules could combine into organic compounds.
What did miller-urey find testing ocarinas hypothesis
In lab conditions similar to early earth (reducing atmosphere) he found one week later all 22 amino acids had been synthesized (sugar, pyrimidine and purine bases, AA, ATP). Showed organic molecules can for in a strongly reducing atmosphere
Describe stage 2 of oparins hypothesis
Polymer formation
Monomers could have combined to form organic polymers. Same energy sources. Clay as substratum for polymerization? -> dropping sln of AA on hot clay results in spontaneous formation of polymers
Describe stage 3 of oparins hypothesis
Protocells
Polymers aggregated into complex, organized, cell-like structures called protocells
Cell-like vesicles form spontaneously in the lab i.e. coacervate droplets, liposomes
Describe protocells
Structural organization, simple homeostasis, simple reproduction, simple metabolism
Step 4 of oparins theory
Self replication
Need two things: enzymes to catalyze reaction and a template
RNA
RNA world? Describe RNA
Single stranded genetic material
Forms enzymes which accelerate reactions called ribozymes
Could have facilitated replication and reaction catalysis on early Earth
Natural selection in an RNA world?
Variation among RNA strands due to copying error + Replication + Some strands better at competing for nucleotides and replicating
Natural select for shape, stability, replication accuracy & speed most suited to environment
Describe protocols with different types of RNA
Protocells able to take up RNA with superior replication and catalytic abilities would have been more successful than those with inferior or no RNA.
