Big Ideas from Chapter Big Ideas from Chapter 2626

4.6 billion years in Earth’s history 4.6 billion years in Earth’s history

Much change has taken placeMuch change has taken place

Abiotic --> LifeAbiotic --> Life

Many changes in the abiotic environmentMany changes in the abiotic environment

4 stages:4 stages:

Conditions of early Earth allow for abiotic Conditions of early Earth allow for abiotic synthesis of small moleculessynthesis of small molecules

Small molecules build more complex Small molecules build more complex polymerspolymers

Polymers are packaged into protobiontsPolymers are packaged into protobionts

Self replicating molecules allow for Self replicating molecules allow for inheritanceinheritance

ProtobiontsProtobionts

droplets of abiotically produced molecules droplets of abiotically produced molecules including carbohydrates, lipids, amino acids, including carbohydrates, lipids, amino acids, and ultimately nucleic acidand ultimately nucleic acid

Like cells: exhibit simple reproduction, internal Like cells: exhibit simple reproduction, internal environment protected within a membrane, environment protected within a membrane, simple enzymatic metabolism (breakdown of simple enzymatic metabolism (breakdown of molecules to release energy)molecules to release energy)

Major shifts in lifeMajor shifts in life

Protobiont --> prokaryotesProtobiont --> prokaryotes

Prokaryotes --> EukaryotesProkaryotes --> Eukaryotes

Life colonizes the landLife colonizes the land

ProkaryotesProkaryotes

Bacterial cells capable of producing substances Bacterial cells capable of producing substances required by the cell required by the cell

Prokaryotic autotrophs - cyanobacteria - can Prokaryotic autotrophs - cyanobacteria - can assemble organic compounds needed to assemble organic compounds needed to survivesurvive

Prokaryotic heterotrophs can use the Prokaryotic heterotrophs can use the products released by the autotrophs or products released by the autotrophs or feed on them directlyfeed on them directly

Oxygen RevolutionOxygen Revolution

Photosynthetic cyanobacteria - O2 given off as Photosynthetic cyanobacteria - O2 given off as a byproduct - oxygen begins to accumulate in a byproduct - oxygen begins to accumulate in Earth’s atmosphereEarth’s atmosphere

Changing environment - selectionChanging environment - selection

Rise of EukaryotesRise of Eukaryotes

For a long time, prokaryotes are the sole For a long time, prokaryotes are the sole inhabitants of Earthinhabitants of Earth

Eventually, eukaryotes evolve through Eventually, eukaryotes evolve through endosymbiosisendosymbiosis

EndosymbiosisEndosymbiosis

Read the definition of endosymbiosis on the Read the definition of endosymbiosis on the boardboard

Talk with your neighbor - can you think of Talk with your neighbor - can you think of any endosymbiotic relationships between any endosymbiotic relationships between species?species?

EndosymbiosisEndosymbiosis

The mutualistic endosymbiotic relationship The mutualistic endosymbiotic relationship between different prokaryotes lead to between different prokaryotes lead to eukaryotes - complex cells with specialized eukaryotes - complex cells with specialized organellesorganelles

VideosVideos

EndosymbiosisEndosymbiosis

Evidence supporting endosymbiosis: Evidence supporting endosymbiosis:

DNADNA

Electron transport chainsElectron transport chains

Enclosed in internal membraneEnclosed in internal membrane

Cell division of organelles resembles binary Cell division of organelles resembles binary fissionfission

MulticellularityMulticellularity

Similar eukaryotic cells begin living in colonies Similar eukaryotic cells begin living in colonies and continue to specialize furtherand continue to specialize further

Multicellular organisms are comprised of Multicellular organisms are comprised of different specialized cell typesdifferent specialized cell types

EvolutionEvolution

Life changes over timeLife changes over time

Natural selectionNatural selection

Unplanned and responsive to changing Unplanned and responsive to changing conditions of the environmentconditions of the environment

Many scientists are investigating the notion of Many scientists are investigating the notion of change over time - both abiotic and bioticchange over time - both abiotic and biotic