Formation of our Universe 10-20 billion years ago Formation of our solar system and Earth 4.6...
-
Upload
vernon-norris -
Category
Documents
-
view
220 -
download
1
Transcript of Formation of our Universe 10-20 billion years ago Formation of our solar system and Earth 4.6...
Formation of our Universe10-20 billion years ago
Formation of our solar system and Earth4.6 billion years ago
Cooling of Earth, formation of oceans, hospitable environs3.9 billion years ago
Formation of Cenancestor3.6 to 4.1 billion years ago
Existence of diverse domains Bacteria, Eukarya and Archaea 2.5 billion years ago
common ancestor
(Cenancestor)
Bacteria
Eukarya
Archaea
Early Earth and Origins of Life
1. Abiotic synthesis (inorganic > organic)
Oparin & Haldane hypothesis (1920s)Urey & Miller (1953)
• Joining of monomers > polymersFox (1950s-60s)
• Packaging of protobiontsOparin hypothesis (1920s)Fox (1950s-60s)
• Self-replicating moleculesCech (1980s)Altman (1980s)
Hypotheses of Early Life: Cenancestor formation
(4 main phases)
1. Abiotic synthesis (inorganic > organic)
Oparin & Haldane hypothesis (1920s)Urey & Miller (1953)
• Joining of monomers > polymersFox (1950s-60s)
• Packaging of protobiontsOparin hypothesis (1920s)Fox (1950s-60s)
• Self-replicating moleculesCech (1980s)Altman (1980s)
Hypotheses of Early Life: Cenancestor formation
(4 main phases)
Abiotic synthesis: Early Earth environment
•Oparin & Haldane Hypothesis (1920s)
•No O2
•Reducing environment favors synthesis
•CO2 NH3 H2 H2O CH4 H2S
•Lightning, UV irradiation, etc.
•“Primordial Soup” hypothesis
Stanley Miller, Age 23
Miller and Urey, 1953
• Bottom flask heated > vaporization
• Electric sparks applied to top flask
• Ran for 1 week• Results:
• Water became pink, then red, and turbid
• Analysis of contents reveals organic compounds• amino acids (alanine and
glycine)• sugars• lipids• building blocks of nucleic
acids
1. Abiotic synthesis (inorganic > organic)
Oparin & Haldane hypothesis (1920s)Urey & Miller (1953)
• Joining of monomers > polymersFox (1950s-60s)
• Packaging of protobiontsOparin hypothesis (1920s)Fox (1950s-60s)
• Self-replicating moleculesCech (1980s)Altman (1980s)
Hypotheses of Early Life: Cenancestor formation
(4 main phases)
Sydney Fox: Simple polymers (1950s)
•amino acids (monomers)
•Heat
•Hot sand, clay, rock
•polypeptides (polymers)
*dripped amino acids over hot sand, clay, rock and found that given the proper conditions, monomers would join to form polymers*in same manner were able to form proteinoids (a type of protobiont) as outlined in next section
1. Abiotic synthesis (inorganic > organic)
Oparin & Haldane hypothesis (1920s)Urey & Miller (1953)
• Joining of monomers > polymersFox (1950s-60s)
• Packaging of protobiontsOparin hypothesis (1920s)Fox (1950s-60s)
• Self-replicating moleculesCech (1980s) Altman (1980s)
Hypotheses of Early Life: Cenancestor formation
(4 main phases)
Protobionts: aggregates of abiotically produced molecules surrounded by
membrane•Oparin (1920s) coined the term
• “bubble hypothesis”
•Sydney Fox (1950s-60s) demonstrated with proteins as “membrane” (proteinoids)
•Maintain internal chemical environment separate from surroundings
•Some properties associated with life
• reproduction- can “duplicate” & “divide”
• “metabolism”- can take up substances; can set up simple metabolic reactions inside
Protobionts
coacervates, proteinoids, micelles, liposomes, microspheres
•synonyms and different names depending on what “membrane” is made of:
Liposome formation
•Amphiphilic lipids form micelles and liposomes
•Hydrophilic (water-loving) heads and hydrophobic (water-hating) tails self-assemble in agitated H2O
•Can grow and shrink in the presence of salts
1. Abiotic synthesis (inorganic > organic)
Oparin & Haldane hypothesis (1920s)Urey & Miller (1953)
• Joining of monomers > polymersFox (1950s-60s)
• Packaging of protobiontsOparin hypothesis (1920s)Fox (1950s-60s)
• Self-replicating moleculesCech (1980s) Altman (1980s)
Hypotheses of Early Life: Cenancestor formation
(4 main phases)
Ribozymes = RNA as an enzyme
•RNA-directed catalysis discovered in nature (1980s)
•Tom Cech - self splicing introns
•Syndey Altman - tRNA cleavage
Ribozymes & the “RNA World”
• RNA may have been the first genetic material
• RNA simpler than DNA
• error-prone polymerization produces “mutations”- diversity in “offspring”
• natural selection of “offspring” with more efficient catalysis leads to “evolution”
• idea that enzymatic activity appears first and specificity evolves later
Ribozymes & the “RNA World”
Ribozymes & the “RNA World”
Modern precedent for idea of RNA as self-replicating genetic material
• RNA viruses: RNA as sole genetic material (no DNA intermediates)
• RNA molecules involved in many types of polymerization in “modern” cells
• Telomere (DNA end structures) replication
• Ribosome and tRNA (Translation)
Formation of our Universe10-20 billion years ago
Formation of our solar system and Earth4.6 billion years ago
Cooling of Earth, formation of oceans, hospitable environs3.9 billion years ago
Formation of Cenancestor3.6 to 4.1 billion years ago
Existence of diverse domains Bacteria, Eukarya and Archaea 2.5 billion years ago
common ancestor
(Cenancestor)
Bacteria
Eukarya
Archaea
Early Earth and Origins of Life
Hypothesis: Going from Cenancestor to 3 Domains
I. Prokaryotes oxygenate the atmosphere
•cellular metabolism evolved in prokaryotes•first organisms are chemoheterotrophs
•no oxygen in atmosphere (so anaerobic)•only food is organic matter in primordial soup
Hypothesis: Going from Cenancestor to 3 Domains
I. Prokaryotes oxygenate the atmosphere
•second to evolve are simple autotrophs•give off oxygen as by product•this leads to the oxygenation of atmosphere•some hypothesize that these were photosynthetic Cyanobacteria-like organisms•third to evolve are heterotrophs that use oxygen (aerobic)
This is the Heterotroph Hypothesis:
chemoheterotrophs > autotrophs > heterotrophs no O2 present produce O2 use O2
Hypothesis: Going from Cenancestor to 3 Domains
I. Prokaryotes oxygenate the atmosphere
CytoplasmDNA
Plasmamembrane
Ancestralprokaryote
Infolding ofplasma membrane
Endoplasmicreticulum
Nuclear envelope
Nucleus
Engulfingof aerobic
heterotrophicprokaryote
Cell with nucleusand endomembranesystem
Mitochondrion
Ancestralheterotrophiceukaryote
Plastid
Mitochondrion
Engulfing ofphotosyntheticprokaryote insome cells
Ancestral Photosyntheticeukaryote
How we got organelles-
the hypothesis
Hypothesis: Going from Cenancestor to 3 Domains
II. Going from prokaryotes to eukaryotes
Hypothesis: Going from Cenancestor to 3 Domains
II. Going from prokaryotes to eukaryotes
•First, membrane in-folding created endoplasmic reticulum and nucleus
Hypothesis: Going from Cenancestor to 3 Domains
II. Going from prokaryotes to eukaryotes
•second, endosymbiosis led to formation of mitochondria and chloroplasts
Endosymbiotic Theory
mitochondria from
heterotrophic (aerobic)
prokaryote
chloroplasts from
photosynthetic prokaryote
(Cyanobacteria?)