Chapter 26 Early Earth and the Origin of Life

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Chapter 26Early Earth and the Origin of Life
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• Major events in earths history

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• Major events in earths history
• 4.5 billion years ago
• Earth is formed

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• Major events in earths history
• 3.5 billion years ago
• Earliest fossil prokaryotes

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• Major events in earths history
• 2.7 billion years ago
• Oxygen accumulates in atmosphere

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• Major events in earths history
• 2.7 billion years ago
• Oxygen accumulates in atmosphere
• Cyanobacteria evolve oxidative photosynthesis

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• Major events in earths history
• 2.1 billion years ago
• First eukaryotic cells

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• Major events in earths history
• 1.2 billion years ago
• First multicellular algae

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• Major events in earths history
• 600 million years ago
• First animals

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• Major events in earths history
• 540-520 million years ago
• Cambrian explosion

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• Major events in earths history
• 500 million years ago
• Colonization of land

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• Major events in earths history

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• The origin of life
• Abiotic (nonliving) synthesis of small organic
  molecules
• Joining these monomers into polymers
• Origin of self-replicating molecules
• Packaging into probionts (droplets with
  membranes).

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• The origin of life
• Abiotic (nonliving) synthesis of small organic
  molecules
• Joining these monomers into polymers

The Miller-Urey experiment.
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• The origin of life
• 3. Origin of self-replicating molecules.

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• The origin of life
• Packaging into probionts (droplets with
  membranes).

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• Dumb
• kings
• play
• chess
• on
• fine
• green
• sand

domain kingdom phylum class order family genus spe
cies
eukaryote animal chordate mammal anthropoid primat
e homo sapiens
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Domains Kingdoms

• Archaea
• Bacteria
• Eukarya

• Monara
• Monara
• Protista
• Plantae
• Fungi
• Animalia

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Domains Kingdoms

• Archaea
• Bacteria
• Eukarya

• Monera
• Monera
• Protista
• Plantae
• Fungi
• Animalia

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Prokaryotes

• Most have cell walls made of peptidoglycan
• Many have polysaccharide capsule
• Many have sticky fimbriae and pili
• About half move with flagella
• Some have specialized membranes
• DNA in one big loop plus plasmids.

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Prokaryotes

• Photoautotrophs use sunlight
• Chemoautotrophs use inorganic fuels
• Heterotrophs consume carbon.

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Oxygen

• Aerobe uses oxygen
• Anaerobe does not use oxygen
• Obligate aerobes cannot grow without O2
• Obligate anaerobes are poisoned by O2
• Facultative anaerobes use O2 when its available
  but can also do fermentation.

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Nitrogen

• Prokaryotes are able to turn N2 into NH3 in a
  process called nitrogen fixation.

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Archaeabacteria

• Analysis of rRNA shows that some bacteria are
  more closely related to eukaryotes and belong in
  a domain of their own.
• Extremophiles (thermophiles and halophiles)
• Methanogens.

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Symbiosis

• Mutualism
• Commensalism
• Parasitism
• .