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Origin and History of LifeOrigin and History of Life
Where it came from and how Where it came from and how it got hereit got here
Chapter OutlineChapter Outline
Primitive EarthPrimitive Earth Origin of First CellsOrigin of First Cells FossilsFossils The PrecambrianThe Precambrian The PaleozoicThe Paleozoic The MesozoicThe Mesozoic The CenozoicThe Cenozoic Continental DriftContinental Drift Mass ExtinctionsMass Extinctions
BeginningsBeginnings
The Universe (maybe)The Universe (maybe)
Primitive Earth—Not paradise as we Primitive Earth—Not paradise as we know it—much different than Earth know it—much different than Earth todaytoday
Simple to complexSimple to complex
Question: How could these simple Question: How could these simple molecules be made into more molecules be made into more complex ones? complex ones?
Answer: Abundant energy sources, Answer: Abundant energy sources, lots of time. lots of time.
Origin of organic moleculesOrigin of organic molecules
Alexander Oparin (1938) — a Russian Alexander Oparin (1938) — a Russian biochemist with visionbiochemist with vision
Stanley Miller (1953) – tested the Stanley Miller (1953) – tested the hypothesishypothesis
PanspermiaPanspermia
Life brought in on Life brought in on asteroids and asteroids and cometscomets
EX. Deinococcus EX. Deinococcus radioduransradiodurans
Abiotic Chemical Abiotic Chemical EvolutionEvolution
Synthesis and accumulationSynthesis and accumulation PolymerizationPolymerization AggregationAggregation Origin of heredityOrigin of heredity
Keep in mind!!!Keep in mind!!!
Chemical natural selectionChemical natural selection
Conditions of primitive earthConditions of primitive earth
TimescaleTimescale
Evolution of Evolution of MacromoleculesMacromolecules
RNA first hypothesisRNA first hypothesis
Protein first hypothesisProtein first hypothesis
Clay hypothesisClay hypothesis
RNA first hypothesisRNA first hypothesis
RNA contains information like RNA contains information like DNADNA
RNA is catalytic-- -- RNA is catalytic-- -- ribozymes.ribozymes.
Protein First Protein First HypothesisHypothesis
Most enzymes are proteinsMost enzymes are proteins
ProteinoidsProteinoids
Proteinoid microspheresProteinoid microspheres
Faithful replication?Faithful replication?
Clay hypothesisClay hypothesis
Unique chemical properties of clay.Unique chemical properties of clay.
Combines parts of the RNA first and Combines parts of the RNA first and protein first ideas.protein first ideas.
Protocell EvolvesProtocell Evolves
Protocells -- precursors to the Protocells -- precursors to the first true cells.first true cells.
lipid-protein membranelipid-protein membrane Proteinoid microspheresProteinoid microspheres CoacervatesCoacervates LiposomesLiposomes
Energy ManagementEnergy Management
Were the first protocells Were the first protocells heterotrophs or heterotrophs or autotrophs?autotrophs?
FossilsFossils
Fossils are remains and traces of Fossils are remains and traces of past lifepast life
Why are they so rare?Why are they so rare?
Dating FossilsDating Fossils
Relative DatingRelative Dating
Absolute datingAbsolute dating
CombinationCombination
The Precambrian The Precambrian Age of Age of microbes microbes
570 mya - 4.6 bya570 mya - 4.6 bya The First Cells —3.5-4 billion years agoThe First Cells —3.5-4 billion years ago What were they like? What were they like?
Energy management?Energy management?
Aquatic or terrestrial?Aquatic or terrestrial?
Prokaryote or eukaryote?Prokaryote or eukaryote?
Evolution of AutotrophsEvolution of Autotrophs
Life as Energy ManagementLife as Energy Management
ChemoautotrophsChemoautotrophs
PhotoautotrophsPhotoautotrophs
Atmospheric OAtmospheric O22 ~2 BYA ~2 BYA
Atmospheric OAtmospheric O22—SO WHAT?—SO WHAT?
OO2 2 is very reactive—Poisonis very reactive—Poison . .
Cells had to deal with thisCells had to deal with this
AerobicAerobic
AnaerobicAnaerobic
Facultative anaerobesFacultative anaerobes
Changes in atmosphere– OChanges in atmosphere– O22 and ozone. So? and ozone. So?
Consequences for energy acquisitionConsequences for energy acquisition
Eukaryotes evolveEukaryotes evolve
More complexMore complex
Origin? Endosymbiont hypothesisOrigin? Endosymbiont hypothesis
flagellum
cytoplasmrough endoplasmicreticulum
ribosome
microtubules
lysosome
mitochondrion
Golgi complex
plasmamembrane
intermediatefilaments
vesicle
smooth endoplasmicreticulum
free ribosomevesicle
nuclear porechromatin (DNA)
nucleolusnuclear envelope
nucleus
1. Anaerobic, predatoryprokaryotic cell engulfsan aerobic bacterium.
2. Descendants of engulfedbacterium evolve intomitochondria.
3. Mitochondria-containingcell engulfs a photosyntheticbacterium.
4. Descendants of photosyntheticbacterium evolve into chloroplasts.
aerobicbacterium
Multicellularity EvolvesMulticellularity Evolves
Examples?Examples?
Volvox—Simple, Volvox—Simple,
multicellularmulticellular
Advantages?Advantages?
Summary of PrecambrianSummary of Precambrian
Earth formsEarth forms Prokaryotes evolvedProkaryotes evolved PhotosynthesisPhotosynthesis EukaryotesEukaryotes MulticellularityMulticellularity Sexual reproductionSexual reproduction
Paleozoic 2Paleozoic 2
Mass extinction---Disappearance Mass extinction---Disappearance of a large number of species of a large number of species within a relatively small time within a relatively small time interval.interval.
opportunities for speciationopportunities for speciation
PALEOZOIC- MAJOR EVENTSPALEOZOIC- MAJOR EVENTS
What were the major events of What were the major events of the Paleozoic?the Paleozoic?
1.1. three mass extinctionsthree mass extinctions
2.2. Invertebrates dominated – Invertebrates dominated – exoskeletonexoskeleton
3.3. Primitive plants invaded landPrimitive plants invaded land
PALEOZOIC- MAJOR EVENTSPALEOZOIC- MAJOR EVENTS
1.1. Vertebrates appeared (jawless Vertebrates appeared (jawless fishes) -- internal skeletonfishes) -- internal skeleton
2.2. Insects and amphibians invaded Insects and amphibians invaded the land -- -- evolution of flight, the land -- -- evolution of flight, evolution of lungs, evolution of evolution of lungs, evolution of stronger limbs, strengthened stronger limbs, strengthened internal skeletoninternal skeleton
PALEOZOIC- MAJOR EVENTSPALEOZOIC- MAJOR EVENTS
1.1. Reptiles appearReptiles appear
a)a) Shelled eggShelled egg
b)b) Scaly skinScaly skin
c)c) Reptiles diversify amphibians Reptiles diversify amphibians declined declined
2.2. Coal forming forestsCoal forming forests
3.3. Conifers appearConifers appear
MESOZOIC- MAJOR EVENTSMESOZOIC- MAJOR EVENTS
The age of reptilesThe age of reptiles Angiosperms evolve-insects Angiosperms evolve-insects
diversifydiversify Mammals and birdsMammals and birds Evolution of endothermyEvolution of endothermy
QUESTIONSQUESTIONS
From what to did dinosaurs evolve?From what to did dinosaurs evolve? From what to do to mammals From what to do to mammals
evolve?evolve? From what did birds evolve?From what did birds evolve? What caused the mass extinction of What caused the mass extinction of
dinosaurs?dinosaurs? Were the dinosaurs endothermic?Were the dinosaurs endothermic?
Endothermy vs EctothermyEndothermy vs Ectothermy
EndothermyEndothermy
Warm –bloodedWarm –blooded
Requires a high use Requires a high use of energyof energy
High metabolic rateHigh metabolic rate
Disadvantages?Disadvantages?
EctothermyEctothermy
Cold bloodedCold blooded
Less energy necessaryLess energy necessary
Regulation?Regulation?
behavioralbehavioral
structuralstructural
inertial ectothermyinertial ectothermy
Cretaceous Mass Cretaceous Mass ExtinctionExtinction
Bolide theory -- -- the most Bolide theory -- -- the most widely accepted theory of widely accepted theory of the Cretaceous Mass the Cretaceous Mass extinction.extinction.
Bolide -- -- and exploding Bolide -- -- and exploding asteroid.asteroid.
CENOZOIC- MAJOR EVENTSCENOZOIC- MAJOR EVENTS
Three mass extinctionsThree mass extinctions Decline of reptilesDecline of reptiles Diversification ofDiversification of
AngiospermsAngiosperms InsectsInsects BirdsBirds MammalsMammals
Factors That Influence Factors That Influence EvolutionEvolution
Continental DriftContinental Drift Positions of continents and oceans Positions of continents and oceans
are not fixed.are not fixed.
How does this explain the presence How does this explain the presence of marsupials and monotremes in of marsupials and monotremes in Australia?Australia?
Continental DriftContinental Drift
Plate TectonicsPlate Tectonics Movements of Earth’s crust which is Movements of Earth’s crust which is
fragmented into slablike plates that float fragmented into slablike plates that float on a lower hot mantle layer.on a lower hot mantle layer.
Mass extinctionsMass extinctions
A A mass extinctionmass extinction occurs when a large occurs when a large fraction of all living species becomes fraction of all living species becomes rapidly extinct.rapidly extinct.
The fossil record shows that at least five The fossil record shows that at least five major mass extinctions have occurred in major mass extinctions have occurred in the past 500 million years.the past 500 million years.
Impacts of asteroids on Earth are Impacts of asteroids on Earth are suspected as a primary cause of mass suspected as a primary cause of mass extinction.extinction.
Mass ExtinctionsMass Extinctions Mass extinctions have occurred Mass extinctions have occurred
throughout history. At the ends of:throughout history. At the ends of: OrdovicianOrdovician
Continental DriftContinental Drift DevonianDevonian
Bolide EventBolide EventLoss of 70% of marine Loss of 70% of marine invertebratesinvertebrates
Mass ExtinctionsMass Extinctions
PermianPermianExcess carbon dioxide.Excess carbon dioxide.Loss of 90% of ocean species.Loss of 90% of ocean species.
TriassicTriassicMeteorite CollisionMeteorite Collision
Cretaceous—probably a bolide.Cretaceous—probably a bolide.
Permian Mass ExtinctionPermian Mass Extinction
At the end of the Permian period (about At the end of the Permian period (about 245 mya), destroyed 90-95% of marine 245 mya), destroyed 90-95% of marine and 70% of land species.and 70% of land species.
Possibilities?Possibilities? The glaciation of GondwanalandThe glaciation of Gondwanaland the increased fluctuation of global the increased fluctuation of global
temperatures temperatures volcanic eruptions occurring in volcanic eruptions occurring in
SiberiaSiberia
Mass ExtinctionsMass Extinctions
Intrinsic gradualismIntrinsic gradualism
Extinction caused Extinction caused primarily by primarily by climate change or climate change or other gradual other gradual processes.processes.
EX. Global warmingEX. Global warming
Extrinsic Extrinsic catastrophismcatastrophism
Extinction caused by Extinction caused by a catastrophea catastrophe
Ex. Asteroid collision Ex. Asteroid collision with Earthwith Earth