Origins of Life The Scientific Story

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Origins of LifeThe Scientific Story
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Origin of the Universeand the Earth

• 15 billion years ago
• The Big Bang led to the formation of the stars
  of the universe
• The Milky Way is one of many galaxies that make
  up the universe
• The sun is the closest star to us
• 4.6 billion years ago
• Planets of our solar system were formed including
  our earth

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Conditions of the early earth

• very hot
• barren rock
• volcanoes
• lightning
• ultraviolet radiation
• gases
• methane (CH4)
• ammonia (NH3)
• water vapor (H2O)
• hydrogen (H2)
• (Hydrogen sulfide/Hydrogen cyanide)

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Then what?

• The earths temperature cooled over many years
  resulting in condensation and huge rains.
• Oceans formed and covered the earth. These oceans
  were thought to be near boiling point.
• Chemical Evolution took place, rearranging the
  atoms of the gases of the atmosphere in to the
  building blocks of organic compounds.

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Urey and Miller

• 1950s experiment to simulate the conditions of
  the primitive earth.
• Urey and Miller

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Urey and Miller

• What did they find?
• Amino acids and Nucleotides had formed .
• Conclusion?
• Perhaps the building blocks of organic compounds
  could have formed on primitive earth (Chemical
  Evolution)

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The Jump

• It is thought that these compounds began to
  cluster together held by drops of H2O. These
  clusters were called coacervates, or proteinoid
  microspheres
• Scientists believe that this abiotic proteinoid
  microspheres made the jump to become the first
  living cell approximately 3.5 billion years ago.
• Spontaneous Generation??

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What did this first cell look like?

• The first cell was likely
• Aquatic
• Prokaryotic
• Anaerobic
• Heterotrophic (Oparin and Haldanes Heterotroph
  Hypothesis)
• 17-2 Worksheet

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Biological Evolution now begins

• The following time line describes some of the big
  events
• 2 billion years ago
• photosynthetic prokaryotes evolve
• releasing O2 into the atmosphere.
• This brought about two major changes
• Aerobic environment
• Formation of ozone (O3)
• UV-rays ? 2O2 ? O O O O ? O3 O
• Aerobic environment led to aerobic organisms
  evolving
• With 18X more energy they could grow faster,
  reproduce faster and evolve faster.

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What Happened Next?

• 1.5 billions years ago eukaryotes evolved
• Large prokaryotic cell engulfs a smaller
  prokaryotic cell.
• Resulted in the first eukaryotic cell
  (mitochondria and chloroplasts have their own
  DNA!!)
• What likely followed?
• - Aquatic multicellularity
• - Terrestrial Autotrophs
• - Terrestrial Heterotrophs

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Check this out

• Origin of Life Intro
• Origin of Life
• Origin of Life Part 2
• Origin of Life Part 3
  
• Panspermia Part 1
• Panspermia Part 2
• Panspermia Part 3

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Lifes History

• Precambrian 7/8 of earths history earth
  formed, first cell evolved, first aerobes
  evolved, multicellular organisms evolved
• Paleozoic explosion of multicellular diversity
  543-248 million years ago
• Mesozoic Dinosaur era, 248-65 million years ago
• Cenozoic Era of Mammals, Flowering plants,
  Insects and Birds, 65 million years to present,
  including the evolution of man

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Assignment

• Read section 15-1 and 15-2, p. 368-377
• The Puzzle of Lifes Diversity and Ideas that
  Shaped Darwins Thinking
• Describe Lamarks Theories of use and disuse
  and inheritance of acquired characteristics.
• Write a short biography on Charles Darwin

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Theories of Evolution

• Jean-Baptiste Lamarck
• (1744-1829)
• Attempted to explain change
  over time

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Lamarcks Theories

• Use and disuse
• Organisms had a desire to change for the
  better.
• The more an organism used a body part, the
  stronger and more significant it became.
• The less a body part was used it became less
  significant or vestigial.

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Lamarck cont

• Inheritance of acquired characteristics
• Any characteristic acquired could be passed on to
  the next generation.
• Lamarck used his 2 theories to explain the
  evolution of the long neck giraffe

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Charles Darwin
1809-1882
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Darwins Voyage of Discovery
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The Voyage of the Beagle
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Darwins Influences

• Charles Lyell Geologist who wrote about
  geological change over time (geological
  evolution).
• Thomas Malthus Mathematician who wrote an essay
  on population growth and noted that populations
  increased at a greater rate than food supplies
  can handle.
• Alfred Wallace Came to the same conclusions as
  Darwin.
• Georges Cuvier used fossils as evidence of
  extinction

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Charles Darwins Theory of Natural Selection

• Over production
• Organisms produce many more offspring than will
  survive.
• Struggle for existence
• Organisms compete for a limited amount of
  resources
• Variations
• Differences in physical traits can show up in
  organisms of the same species. (These variations
  are a result of genetic mutation.) These changes
  can be passed on to the next generation.

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Natural Selection cont

• Survival of the fittest
• Organisms with traits that give them an advantage
  in the competition will survive and therefore
  pass these traits onto the next generation.
• Origin of new species
• Over many generations these accumulated inherited
  traits will give rise to new species. (gradualism)

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Think about this statement

• Organisms dont change to survive, they survive
  because they change
• With a partner, discuss the meaning of this
  statement.

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