Ch. 12 Notes History of Earth

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Ch. 12 NotesHistory of Earth

• By Brianna Shields
• January 9, 2006

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List the terms in your vocab notebook, leaving
about 3-4 spaces between each term

• Radiometric Dating
• Radioisotope
• Half-life
• Microsphere
• Fossil
• Cyanobacteria
• Eubacteria
• Archaebacteria
• Endosymbiosis

• Protist
• Extinction
• Mass Extinction
• Mycorrhizae
• Mutualism
• Arthropod
• Vertebrate
• Continental Drift

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DO NOW

• The first genetically engineered organism
  involved the transfer of a gene from what
  organism to bacteria?
• What type of organism was the first to be cloned
  in its entirety?
• Which type of test uses blood, semen, hair or
  bone to determine whether an individual was
  present at the scene of a crime?

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GOALS

• Summarize how radioisotopes can be used in
  determining Earths age
• Compare two models that describe how the
  chemicals of life originated
• Describe how cellular organization might have
  begun
• Recognize the importance that a mechanism for
  heredity had to the development of life
• Distinguish between the two groups of prokaryotes
• Describe the evolution of eukaryotes
• Recognize the evolutionary advance first seen in
  protists
• Summarize how mass extinctions have affected the
  evolution of life on Earth
• Relate the development of ozone to the adaptation
  of life to the land
• Identify the first multicellular organisms to
  live on land
• Name the first animals to live on land
• List the first vertebrates to leave the oceans

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How did Life Begin?

• Age of Earth

• 1. Fiery ball of rock
• 2. Surface of Earth cooled
• 3. Water vapor in air condensed to form ocean
  water

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How did Life Begin?

• Measuring the Age of Earth

• Radiometric Dating- estimates age by measuring
  amount of radioactive isotopes

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How did Life Begin?

• Measuring the Age of Earth

• Radioactive Isotopes
• Unstable forms of an element with varying masses
• Break down, give off large amounts of charged
  energy particles (radiation)

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How did Life Begin?

• Measuring the Age of Earth

• Radioactive Decay
• Breakdown of radioactive isotopes into smaller,
  more stable ones
• Half-Life
• Time it takes for one half of a certain amount of
  radioisotope to decay

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How did Life Begin?

• Measuring the Age of Earth

• Age determined by measuring amounts of remaining
  isotopes and their decay products

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How did Life Begin?

• Formation of Lifes Chemicals

• Nonliving matter was energized by sun and
  volcanic heat
• Caused chemical reaction to produce simple
  organic molecules
• Organics became more complex
• First cells developed

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How did Life Begin?

• Primordial Soup Model by Miller and Urey

• Earths oceans once filled with organic molecules
  (soup)
• No oxygen in air only nitrogen, hydrogen,
  water, ammonia, methane
• Solar radiation, volcanic eruptions, lightning
  excited electrons in gases
• Electrons reacted with H in air to form organic
  molecules

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How did Life Begin?

• Testing Miller and Ureys Theory

• Apparatus with hot liquid water at bottom, hot
  gaseous mixture at top
• Electrical spark (lightning) added
• Found complex amino acids, fatty acids in chamber

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How did Life Begin?

• Reevaluating Miller and Ureys Theory

• Mixture of gases in their experiment couldnt
  have existed
• No ozone layer, UV rays would hit planet
  destroying all ammonia and methane
• Without these, no biological molecules could be
  made
• Chemicals of life arent in air, theyre in water

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How did Life Begin?

• Bubble Model

• Ammonia methane gas bubbles formed underwater
  by volcanoes
• Bubbles protect gases from UV rays- chemical
  reactions occurred
• Bubbles rise to ocean surface, releasing organic
  molecules
• Molecules carried by wind, exposed to UV and
  lightning
• Organics become more complex, fall back into
  ocean, cycle continues

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Bubble Model
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How did Life Begin?

• Precursors of the First Cells

• Havent yet made proteins or DNA spontaneously in
  water in the lab (very difficult!)
• Have made short chains of RNA
• RNA- catalyst and info storage
• First self-replicating info
• Assembled first proteins

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How did Life Begin?

• Precursors of the First Cells

• First step towards cells
• Microspheres short amino acid chains that
  gather into tiny droplets in water (like oil in
  water)
• Similarities to cell membranes

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How did Life Begin?

• Precursors of the First Cells

• First step towards cells
• Coacervates- short chains of linked amino acids
  and sugars that form tiny droplets in water

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Assessment One

• Explain how radioisotopes are used to determine
  the age of a rock.
• Critique two scientific models that explain the
  origin of life.
• Describe the first step that may have led toward
  cellular organization.
• Explain how heredity may have arisen.
• Miller and Ureys model is inconsistent with the
  finding that Earths early atmosphere lacked
  which gas?

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How did Life Begin?

• Evolution of Prokaryotes

• Fossil- preserved remains (bone, tooth, shell) or
  imprint of an organism from long ago

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How did Life Begin?

• Evolution of Prokaryotes

• Oldest fossils - photosynthetic prokaryotes
  (cyanobacteria)
• 2.5 billion years old
• Released oxygen into oceans
• Oxygen eventually escaped into air

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How did Life Begin?

• Evolution of Prokaryotes

• Eubacteria
• Cell walls contain peptidoglycan
• Cause disease and decay

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How did Life Begin?

• Evolution of Prokaryotes

• Archaebacteria
• Cell walls lack peptidoglycan
• Unique lipid cell membranes

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How did Life Begin?

• Evolution of Eukaryotes

• Eukaryotes
• Larger
• More Comples
• Internal Membranes
• DNA in a nucleus
• Mitochondria
• Chloroplasts

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How did Life Begin?

• Evolution of Eukaryotes

• Theory of Endosymbiosis
• 1. Mitochondria are descendants of symbiotic,
  aerobic eubacteria
• 2. Chloroplasts are descendants of
  photosynthetic eubacteria

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How did Life Begin?

• Evolution of Eukaryotes

• Theory of Endosymbiosis
• 3. Bacteria entered large cells as prey or
  parasites
• 4. Bacteria began to live there
• 5. Bacteria evolved into mitochondria or
  chloroplasts

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How did Life Begin?

• Evolution of Eukaryotes

• Similarities between mitochondria, chloroplasts
  and bacteria
• Size
• Double Membrane on outside
• Circular DNA (contain genes different from actual
  cell)
• Ribosomes
• Reproduce through fission (independent of host
  cells cycle)

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How did Life Begin?

• Multicellularity

• First kingdom- Protist
• Half earths biomass
• In multicellular organisms- specialized cells
  carry out different jobs
• Ex Protection, reproduction, movement
• Protists evolved into multicellular fungi, plant
  and animal kingdom

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How did Life Begin?

• Origins of Modern Organisms

• A. Cambrian Period (540-505 million years ago)
• Time of great evolutionary expansion
• 1909- Burgess Shale in Canada (major fossils of
  this period found)

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How did Life Begin?

• Origins of Modern Organisms

• B. Ordovician Period (505-438 million years ago)
• Many different animals continued to thrive

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How did Life Begin?

• Mass Extinctions

• A. Extinction- Death of all members of a species

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How did Life Begin?

• Mass Extinctions

• B. Mass Extinction- Episode during which large
  numbers of species become extinct
• Five major events in history

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How did Life Begin?

• Mass Extinctions

• C. Most devastating- end of Permian period
• 245 million years ago
• 96 of all species became extinct
• Cause may have been worldwide geological and
  weather changes

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How did Life Begin?

• Mass Extinctions

• D. Fifth mass extinction
• 2/3 of all land species (including dinosaurs)
  become extinct

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How did Life Begin?

• Mass Extinctions

• E. A sixth mass extinction event?
• May be currently occurring due to destruction of
  tropical rain forests by human activity

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WEBSITES

• ajkf

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Assessment Two

• Contrast the two major groups of prokaryotes
• Analyze Marguliss theory of endosymbiosis,
  citing its strengths and weaknesses
• Compare bacteria with eukaryotes
• Summarize how multicellularity advanced the
  evolutin of protists
• Justify the argument that todays organisms would
  not exist if mass extinctions had not occurred
• The kingdom that includes both multicellular and
  unicellular eukaryotes is called?

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DO NOW

• 1. Which theory attempts to explain the
  evolution of mitochondria and chloroplasts?
• 2. Which kingdom contains both multicellular and
  unicellular eukaryotes?
• 3. Which mass extinction do we think is
  currently occurring?

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How did Life Begin?

• Ozone Layer

• Enabled life forms to leave the ocean that
  protected them from harmful UV rays
• Photo. Cyanobacteria releases oxygen that reacted
  with sun to form ozone
• Ozone accumulated into a layer to protect Earth
  from UV radiation

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How did Life Begin?

• Plants and Fungi on Land

• Plants evolved from photo. bacteria
• Use sunlight to generate nutrients
• Cannot harvest materials from bare rock

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How did Life Begin?

• Plants and Fungi on Land

• Fungi
• Can harvest materials from bare rock
• Cannot use sunlight to generate nutrients

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How did Life Begin?

• Plants and Fungi on Land

• Together, they form a mutualistic relationship
  (both benefit)
• Mycorrhizae- fungus provides minerals to plant,
  and plant provides nutrients to fungi

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How did Life Begin?

• Arthropods

• First animals to successfully invade land (first
  most likely scorpion)
• Hard, outer skeleton
• Segmented body
• Paired, jointed limbs
• Lobsters, crabs, insects, spiders

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How did Life Begin?

• Arthropods

• Insects
• Most plentiful, diverse group on Earth
• First to have wings and fly
• Efficient at searching for food, mates and
  nesting sites

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How did Life Begin?

• Vertebrates (animals with a backbone)

• A. Fishes
• First vertebrates- small jawless fishes
• Jawed fish evolved- allowed predation
• Most successful of living vertebrates
• Developed into land dwellers

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How did Life Begin?

• Vertebrates (animals with a backbone)

• B. Amphibians
• First land vertebrates (to come out of sea)
• Smooth skinned, four legged
• Frogs, toads, salamanders
• Developed lungs for absorbing oxygen from air
• Limbs derived from bones in fish fins
• Strong, flexible internal skeleton for walking
• Lay eggs in moist areas

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How did Life Begin?

• Vertebrates (animals with a backbone)

• C. Reptiles
• Evolved from amphibians
• Snakes, lizards, turtles, crocodiles
• Watertight skin locks moisture in while living on
  land
• Can lay eggs on dry land

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How did Life Begin?

• Vertebrates (animals with a backbone)

• D. Mammals and Birds
• Evolved from reptiles
• 5th mass extinction only dinosaurs that were
  ancestors to birds, small reptiles and small
  mammals survived

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How did Life Begin?

• Continental Drift

• Movement of land masses over Earths surface
  through geologic time
• Explains why there are Marsupials in both
  Australia and South America although they are
  extremely far apart

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WEBSITES

• ajkf

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Assessment Three

• Summarize how ozone was important in enabling
  organisms to live on land
• Name the first multicellular organisms that
  colonized land
• Identify the first kinds of animals to live on
  land
• Describe the first kinds of vertebrates that
  inhabited land
• Defend the argument that invasion of land could
  not have happened until well after the evolution
  of cyanobacteria
• Mycorrhizae are mutualistic relationships between
  the roots of plants and what other type of
  organisms?