lecture 10 Flashcards
accumulation of organic molecules formed _____
The lack of oxygen allowed ______
And there were no ______
primordial soup
molecules to avoid oxidation
living organisms to metabolize the soup
Origin of organic molecules
Deep see vent hypothesis
____ ____ and ____ exit ______ in excess of _____
__________ can be formed in the gradient between hot and cold water
water metal hydrogen sulfide deep sea thermal vents 300˚C precursors to organic molecules
Stage 2 of four stage process to life is ________
This took place on _________
Not in _________
nucleotides and amino acids became polymerized to form dna, rna and proteins
solid surface or tidal pool
prebiotic soup
formation of polypeptide and nucleic acid polymers may occur when and where
when monomers are present and on the surface of clay
stage 3 of four stage process to life
polymers became isolated by boundaries(cell walls)
polymer boundaries does _____
which resulted in
seperates the environment from the internal polymers, (creates their own micro-climate)
protobiont
protobiont
first non living structures that evolved into cells
protobiont characteristics (4)
- membrane separating external environment from internal contents
- polymers inside that contain information (DNA/RNA)
- polymers (proteins) also act as enzymes for additional reactions
- capable of replication (not quite self reproduction)
Coacervates are __________
and are a __________
charged polymers which sponataneously associate with each other
scenario for protobiont formations
microspheres ___________
And are a _________
water filled vesicle with macromolecular boundary
scenario for protobiont formation
liposomes are _____
and are a ______
researchers have shown that clay ______
similar to microspheres but with a lipid outer layer,
(scenario for protobiont formation)
Can catalyze the formation of liposomes that grow and divide
starge 4 of four stage process to life
polymers enclosed in membranes evolved cellular properties
- protobionts developed metabolic functions and self replications
rna have abilitiy to _____ _____ and ______
So scientists favor it as
store information
have capacity to self replicate
are capable of enzymatic activity
the first macromolecule of protobionts
first organisms
They were probably __________ because then they wouldn’t ___________ or have to ___________
And were probabably _________ because the oceans _________
- prokaryotes, single celled microorganisms with anaerobic metabolism
- anaerobic heterotrophs
- require oxygen
- or need to evolve additional metabolic pathways to make organic molecules
- thermophiles
- were continuously heated by impacts of meteorites and volcanoes
Anaerobic heterotrophs metabolize ________ via _______
Because ________ were made slowly the anaerobic heterotrophs would have ___________ so then _____ evolved and had an _____
- organic molecules
- fermentation
- organic molecules
- exhausted the supply quickly
- cells that evolved to synthesize own organic organic molecule supply
- advantage
Anaerobic autotrophs
chemoautotrophs and photoautotrophs
anaerobic chemoautotrophs
obtain carbon from CO2 but obtain energy from the reduction of inorganic chemical bonds
anaerobic photoautotrophs
obtain energy from sunlight to fix co2 into carbon compounds
following anaerobes
photoautotrophs with oxygenic photosynthesis
key innovation made by photoautorophs _______
Which had an advantage because ______
This was termed ________
because _______
use of H20 as the electron donor
water was plentiful
oxygenic photosynthesis
oxygen was a byproduct of this new process
Original elements
hydrogen and helium
earth an accumulation of
comets and asteroids
Original earth was ______
Then it ______
Volcanoes and other vents ______
Which consisted of __________
Too hot for water, and so no life
cooled enough to solidify and oceans formed
formed new atmosphere
CO2, N2, H2S, H20, maybe NH4 and CH4
Evidence of oxygen appearing from _____
These layers are called _____
- the presence of rusted iron found in ancient rocks of the time (because oxygen is need for rust)
- banded iron formation
First stage of processes to life
which formed in the
some believe the earth was seeded via
Origin of organic molecules
Ancestral atmosphere of the earth (replicate in lab)
comets/asteroids with organic molecules
Three main hypothesis for primordial soup development
Reducing atmosphere hypothesis
Extraterrestrial hypothesis
Deep sea vent hypothesis
Reducing atmosphere hypothesis
Ancestral atmosphere consisted of \_\_\_\_\_\_ With O2 absent \_\_\_\_\_\_ Under these conditions \_\_\_\_\_\_ and \_\_\_\_\_ experimented to see if they could \_\_\_\_\_\_\_ They found \_\_\_\_\_\_\_\_ New evidence suggests \_\_\_\_- but was \_\_\_\_\_\_ consisting of \_\_\_\_\_\_ But still \_\_\_\_\_\_\_\_
water vapour, H2, methane(CH4), ammonia(NH3)
the atmosphere is a reducing environment
Miller
Urey
Produce organic molecules in the laboratory
simple organic compounds in their trap
The original environment wasn’t reducing
CO, CO2, N2 and H20
Organic molecules were produced from experiments
Extraterrestrial hypothesis
Meteorites contain _______
which includes __________
Opponents argue ______
substantial amounts of organic carbon
amino acids and nucleic acids
Most of this would be destroyed in heating and collision
formation of polypeptides and nucleic acid polymers may occur on ______ which is used in ______
surface of clay,
many industrial organic reations
Possible scenarios for protobiont formation
Coacervates
microspheres
liposomes
There are limitation to both kinds of ______
Which include requiring _____
Anaerobic autotrophy
reduced elements or compounds to provide energy(supply could be exhausted again)
