Download Origins of Life

Origins of Life
“The Scientific Story”
Origin of the Universe
and the Earth
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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
Conditions of the early earth:
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very hot
barren rock
volcanoes
lightning
ultraviolet radiation
gases:
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methane (CH4)
ammonia (NH3)
water vapor (H2O)
hydrogen (H2)
(Hydrogen sulfide/Hydrogen cyanide)
Then what?
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The earth’s 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.
Organic Compound
Building Block
Protein
Amino Acids
Nucleic Acids
Nucleotides
Carbohydrates
Simple Sugars
Lipids
Glycerol and Fatty Acids
Urey and Miller
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1950’s experiment to simulate the
conditions of the primitive earth.
Urey and Miller
Urey and Miller
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What did they find?
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Amino acids and Nucleotides had formed .
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Conclusion?
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Perhaps the building blocks of organic
compounds could have formed on
primitive earth (Chemical Evolution)
The Jump…
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It is thought that these compounds began to
cluster together held by lipid molecules
accumulating.. These clusters were called
coacervates, or “proteinoid microspheres”
Scientists believe that these “abiotic” proteinoid
microspheres made the jump to become the first
living cell approximately 3.5 billion years ago.
Spontaneous Generation??
What did this first cell look like?
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The first cell was likely:
Aquatic
Prokaryotic
Anaerobic
Heterotrophic (Oparin and Haldane’s
Heterotroph Hypothesis)
Biological Evolution now begins
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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
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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.
What Happened Next?
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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 NFB Evolution
- Terrestrial Autotrophs
- Terrestrial Heterotrophs
How Did Life Begin? How Did Life Begin 2
Life’s Eras
Life’s History
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Precambrian – 7/8 of earth’s 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
Assignment
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Read section 15-1 and 15-2, p. 368-377
“The Puzzle of Life’s Diversity” and “Ideas
that Shaped Darwin’s Thinking”
Describe Lamark’s Theories of “use and
disuse” and “inheritance of acquired
characteristics”.
Write a short biography on Charles Darwin
Theories of Evolution
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Jean-Baptiste Lamarck
(1744-1829)
Attempted to explain
change over time
Lamarck’s Theories
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Organisms had a “desire” to change for
the better.
1. “Use and Disuse”
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.
Lamarck cont…
2.
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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
What is wrong with Lamarck’s ideas??
Lamarck’s Giraffe!
Charles Darwin
1809-1882
Darwin’s Voyage of Discovery
The Voyage of the Beagle
Darwin’s Influences
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Charles Lyell/James Hutton – Geologists 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.
Georges Cuvier – used fossils as evidence of
extinction
Alfred Wallace – Came to the same conclusions
as Darwin.
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Charles Darwin’s Theory of Natural
Selection
Over production
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Struggle for existence
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Organisms produce many more offspring than will
survive.
Organisms compete for a limited amount of
resources
Variations
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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.
Natural Selection cont…
4.
Survival of the fittest
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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
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Over many generations these accumulated
inherited traits will give rise to new species.
(gradualism)
Think about this statement
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“Organisms don’t change to survive, they
survive because they change”
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With a partner, discuss the meaning of
this statement.
The Buffalo Theory.docx
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Kruger
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Galapagos Islands
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Sea Turtle Story
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Laying Eggs
Hatching Eggs
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Darwin’s explanation of evolution is called
Natural Selection.
What does the term Artificial Selection
mean? Discuss this with a neighbour.
Samuri Crab