Evolution

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Evolution

• 01.22.08 / 01.23.08

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What if I dont believe it?

• Consider Acts 1722-23
• Paul then stood up in the meeting of the
  Areopagus and said "Men of Athens! I see that in
  every way you are very religious. For as I walked
  around and looked carefully at your objects of
  worship, I even found an altar with this
  inscription TO AN UNKNOWN GOD. Now what you
  worship as something unknown I am going to
  proclaim to you.

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What if I dont believe it?

• Ask yourself if you even understand it?
• Realize that you really do believe it
• at least, some of it.
• Evolution is a theory, which means its complex
• Parts of evolution are fact that no one contests

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So, why should I care?

• Do you know why purebred dogs are more likely to
  have health problems than mutts?
• Do you know why 1.7 million Americans now
  contract superbug infections each year?
• Pay attention and maybe youll find out even more.

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So, why should I care?

• Its everywhere

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Chapter 14History of Life

• 01.22.08 / 01.23.08

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Biogenesis

• Biogenesis all living things comes from other
  living things
• From Greek bioun meaning life and gignesthai
  meaning beginning
• Like the book of Genesis (the beginning)
• Spontaneous generation the now abandoned view
  that life spontaneously arises
• used to explain why maggots appeared on rotting
  meat

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Biogenesis

• Redis experiment (1600s)
• observed that maggots turned into flies and that
  maggots often seemed to appear after flies had
  been in the area
• experimental group had meat covered with netting
  to keep flies out
• control group had meat exposed to flies
• demonstrated that maggots are produced from
  living flies

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Biogenesis

• Redis experiment
• Hypothesis maggots develop from flies
• Independent variable exposure to flies
• Dependent variable development of maggots
• Data observed maggots (yes or no)
• Conclusion maggots form from flies, not
  spontaneously

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Biogenesis

• Spallanzanis experiment (1700s)
• Tested the idea of a vital force
• Boiled broth to kill microorganisms
• Sealed flask of exp. group
• Left control flask open
• Critics said the heat killed the vital force

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Biogenesis

• Pasteurs experiment (1800s)
• used a curved, but open, neck on a flask to keep
  microorganisms out of broth
• broth remained clean for up to a year
• once the neck was broken, broth was contaminated
  within a day

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Cell Theory

• These experiments led to Cell Theory, which
  states
• All living organisms are made of one or more
  cells
• Cells are the basic unit of structure and
  function in all living organisms
• All cells come from other cells
• In general, evolutionary theory makes no effort
  to explain how life began, just how it has changed

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Earths History

• The earth is about 4.6 billion years old
• Age is determined by radiometric dating
• radioactive materials decay from their parent
  isotopes into daughter isotopes
• this decay occurs at a specific rate, known as
  half-life

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Earths History

• So, how did life begin?
• Oparin and Haldane proposed in the 1920s that the
  earths early atmosphere contained large amounts
  of ammonia, hydrogen gas, water vapor and methane
• These chemicals might have collected in water
  and, with the energy of lightning and solar
  radiation, combined into macromolecules, such as
  amino acids

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Earths History

• Miller-Urey experiment
• Tested Oparin and Haldanes hypothesis by
  combining inorganic chemicals with electricity
• Created organic materials, such as amino acids
• Various revisions have been made to test
  differing hypotheses for the early atmosphere

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Earths History

• But, didnt I say evolution does not try to
  explain how life began?
• Yes
• Miller received his PhD in chemistry, not biology
• But, science is interdisciplinary, so I said, in
  general.
• In general, evolutionary theory makes no effort
  to explain how life began, just how it has
  changed

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Earths History

• That leads us to astrobiology
• Formerly known as exobiology
• Study of life in the universe
• Organic molecules have been found in meteorites

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Earths History

• Experiments have shown some organic molecules can
  form spontaneously
• Microspheres are made of proteins that form a
  membrane
• a certain type of radioactive microsphere is now
  used in oncology
• Coacervates are made of various molecules,
  including fats, amino acids and sugars

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The First Life-Forms

• Read if you want to know more.

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Check-up

• Describe the difference between spontaneous
  generation and biogenesis.
• Describe Redis experiment.
• Describe Spallanzanis experiment.
• Describe Pasteurs experiment.

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Check-up

• How do you personally benefit from the research
  of Spallanzani and Pasteur?
• Describe cell theory.
• Describe the Miller-Urey experiment and its
  importance.