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I. How Did Life Begin?. Prior to the 17 th century: 1. Spontaneous Generation : The belief that living things could come from non-living things. Francesco Redi (1668) Italian scientist. Attempted to discredit Spontaneous Generation. Experimented to prove that maggots came from flies.

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I how did life begin
I. How Did Life Begin?

Prior to the 17th century:

1. Spontaneous Generation:

The belief that living things could come from non-living things.

Francesco redi 1668 italian scientist
Francesco Redi (1668)Italian scientist

  • Attempted to discredit Spontaneous Generation.

  • Experimented to prove that maggots came from flies

Redi s exeriment

1668 – Experiment showing how maggots come from flies

Lazzaro spallanzani 1700
LazzaroSpallanzani (1700)

Italian scientist

Experimented with spontaneous generation of microorganisms.

1. Created meat broth

2. Boiled broth to kill microorganisms

3. Capped some flasks and left others open.

Spallazani s experiment
Spallazani’s Experiment

Opponents of his study claimed that he overheated the samples…

Destroying the VITAL FORCE

Louis pasteur 1800 s french scientist
Louis Pasteur (1800’s)French scientist

*The conclusions of Pasteur, brought about the theory of BIOGENESIS – Living things come from other living things

B formation of the earth
B. Formation Of The Earth

  • About 5 billion years ago, the solar system was a mass of swirling gas and dust.

  • Possible result of a SUPERNOVA

I how did life begin

As millions of years passed, a large amount of material collapsed to the center and created the sun.

Around 4.6 billion years ago, the earth and some of the other planets were formed.

I how did life begin

As earth cooled, water vapor in the air condensed to form water and the first oceans.

3.8 to 3.9 billion years ago.

C measuring earth s age
C. Measuring Earth’s Age water and the first oceans.

Radiometric dating:

Estimate the age of an object by measuring its content of radioactive isotopes.

Radioactive isotopes:

Unstable and “decay” over time.


The time that it takes for a radioactive isotope to decay by one half

D life on the earth
D. water and the first oceans. Life On The Earth

The oldest evidence of life on the earth is found in rock estimated to be 3.5 billion years old.

The evidence shows in the form of FOSSILS.

The first fossils were referred to as MICROFOSSILS, ancient prokaryotic cells.

I how did life begin

  • A. water and the first oceans. Primordial Soup Model

  • Alexander Oparin (1923)

  • Soviet scientist

  • Gases of the primitive atmosphere came together and created simple organic compounds

1. Formation of Simple Organic Compounds

I how did life begin

  • * DID NOT run any experiments to support theory

I how did life begin

-In 1953, compoundsAmericans, Stanley MillerandHarold Urey, set up an experiment that was based on Oparin’s theory.

B the bubble model

Ammonia and Methane were released from volcanoes into bubbles

Bubbles rise to the surface and burst

B. The Bubble Model

2 formation of complex organic compounds
2. Formation of Complex Organic Compounds bubbles

  • Formation of protein occurred either by amino acids spontaneously combining…

  • Or they were heated in the absence of oxygen

    -Similar mechanisms may have led to the formation of carbohydrates,lipids, and nucleic acids

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3. Concentration and Enclosure bubbles

Proteins clump together to form microscopic droplets…

  • Coacervates- droplets of different types of irregularly shaped molecules .

    Includes Amino Acids and sugars

B microspheres
B. Microspheres bubbles-

  • Round, usually from one type of molecule.

  • Separated from the environment by a membrane

  • Chemical reactions occur here more easily than in water

  • Can bud off

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4. bubblesEvolution of Growth, Metabolism, and Reproduction

Coacervatesand microspheres lack the complexity of living cells …

-They can grow

-They can bud

  • They lack the ability to respond to natural selection.

5 the role of rna
5. The Role of RNA bubbles


A special type of RNA was discovered to be able to act like an enzyme

They can replicate themselves

Research indicates life may have started with RNA

I how did life begin

  • II. Evolution of Cellular Life bubbles

  • A. The First Prokaryotes

    Scientists hypothesize that the first cells were:

  • Anaerobic

  • Heterotrophic

  • Prokaryotic

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B. bubblesThe First Eukaryotes

  • Some early Eukaryotes may have gone through a relationship known as SYMBIOSIS.

    Endosymbiosis Theory:

  • Prokaryotic intracellular parasites evolved into various cell organelles

  • Evidence in the mitochondria and chloroplasts

Life invaded land
Life Invaded Land bubbles

  • Cyanobacteria: photosynthesizing organisms gave off oxygen as a waste product. (At about 2.8 billion years ago)

  • Oxygen had two effects on the environment:

    1) Those organism that could bond oxygen to other compounds survived

    - beginning of aerobic respiration.

    2) Ozone (O3) was created

Lamarck s explanation
Lamarck’s Explanation bubbles

  • French scientist (1744-1829)

  • Similar species descended from common ancestors

    ACQUIRED TRAITS: explanation for species change.

  • Changes arise from experiences and behavior over a lifetime

  • Not determined by genes.

    EXAMPLES: web feet, giraffe neck, tails

    “USE and DISUSE”

Charles darwin
Charles Darwin bubbles

  • Went to medical school

  • Study become a minister

  • Interested wildlife and the environment

  • Took a voyage on a ship, the BEAGLE, as the boats naturalist

I how did life begin

Darwin proposed bubblesa mechanism for evolution

Natural Selection: occurs because of ADAPTATIONS

Published a book: “On the Origin of Species”1859, 1 year after Alfred Wallace (same basic ideas)

Evolution by natural selection
Evolution by Natural Selection bubbles

“Human populations are able to increase faster than the food supply can”– Thomas Malthus 1798

  • Only a limited number of offspring survive to reproduce

  • Individuals with traits that best suit their environment are most likely to survive and reproduce

Darwin s theories
Darwin’s Theories bubbles

Descent with modification:

Newer life forms appearing in the fossil record are modified versions of the old species

Modification by Natural Selection:

Mechanism for how evolution can occur.

Why some organisms survive when others do not
Why some organisms survive when others do not: bubbles

The environment affects individuals differently

Some traits provide an advantage

Populations ADAPT as the proportion of favorable genes increases

FITNESS: Single organisms genetic contribution to the next generation.

Favorable traits provide an ADAPTIVE ADVANTAGE

Adaptations: bubbles

Inherited traits that have become popular due to a selective advantage

Darwin s theory
Darwin’s Theory: bubbles

Based on 4 major points….

  • Inherited variation exists within the genes of every population

    2. Some individuals are better suited for their environments

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The scopes trial
The Scopes Trial survive and have offspring

Pbs video on evolution
PBS VIDEO ON EVOLUTION survive and have offspring

Darwin and evolution
Darwin and Evolution survive and have offspring

Evidence of evolution

The Fossil Record survive and have offspring:


Preserved or mineralized remains or imprints of an organism that lived long ago

Evidence of Evolution

Concerns with using fossils for source of evidence
Concerns with survive and have offspringusing fossils for source of evidence

  • The fossil record is NOT COMPLETE

  • Many times genetic information is not available from the fossils

  • Not all organisms are equally likely to be fossilized

Types of fossils
Types of Fossils survive and have offspring

  • Imprints

    A film of carbon remains after other elements of an organism have decayed

  • Mold

    created by the impression of a shape/track

  • Cast

    sediment fills in a cavity left by a fossil

Fossil video
Fossil Video survive and have offspring

Fossil dating
FOSSIL DATING survive and have offspring

  • Ways of determining fossil age:

    1. Position within sedimentary rock

  • Look at different strata:

    • Deeper is older

2 carbon dating
2) Carbon dating survive and have offspring

  • Dating is done by comparing ratio of carbon 12 and carbon 14

  • Used to date things up to 50,000yrs. old

I how did life begin

  • Parent

  • Daughter

  • Half Life (yrs)

  • Dating Range (yrs)

  • Materials

  • Carbon-14

  • Nitrogen-14

  • 5730±30

  • 0100-70,000

  • Anything with C

  • Potassium-40

  • Argon-40Calcium-40

  • 1.3 billion

  • 50,000-4.6 billion

  • MuscoviteBiotiteHornblendeWhole volcanic rock

  • Uranium-238

  • Uranium-235Uranium-232

  • Lead-206

  • Lead-207Lead-208

  • 4.5 billion

  • 710 million14 billion

  • 10 million-4.6 billion

  • Zircon,U containing

  • Rubidium-87

  • Strontium-87

  • 47 billion

  • 10 million-4.6 billion

  • MuscoviteBiotitePotassium FeldsparWhole metamorphicor Igneous rock

Evidence from living organisms
Evidence From Living Organisms survive and have offspring

1) Evidence of Common Ancestry

-Organisms that are similar in structure had a common ancestor

2 homologous structures vs analogous structures
2. survive and have offspringHomologous Structures vs. Analogous Structures

  • Homologous:

  • Structures that are embryologically similar and functionally different

    B. Analogous:

  • Structures that are

    embyologically different

    but function the same

Homologous structures
Homologous Structures survive and have offspring

4 biochemical comparisons

-Examine biochemical compounds within organisms survive and have offspring

3. Vestigial Organs:

Organs that are seemingly functionless

4. Biochemical Comparisons:

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5. survive and have offspringEmbryological Development:

Compare organisms at various stages of development




Common ancestor