CP Biology Name ______ ____________ 2015-2016

UNIT 3A: Origins of Life

How did Life Begin?

For thousands of years people believed that living or-

ganisms originated from nonliving matter.

1) Abiogenesis or Spontaneous Generation : the idea that life can arise from nonliving material. (Ex: haystacks; flies come from rotting meat; bacteria arise from broth)

Francisco Redi in the 1600’s and Louis Pasteur in 1862 conducted experiments which disproved the theory of spontaneous generation.

2) Biogenesis : the idea of life arising from other living things. (Ex. Cats make cats; humans make humans, etc.)

Where did the first life come from? _______________________________________________________________________________________________________

Franceso Redi’s Experiment:_____________________________________________________________________________________________________________________________________________________________________________________________________

Louis Pasteur’s Experiment:_____________________________________________________________________________________________________________________________________________________________________________________________________

Origins of the Earth

Big Bang Theory (1927): idea which explains what hap-pened at the very beginning of our universe (~13.7 bya) – began as an infinitely small, hot dense “speck” that in-flated, expanded and cooled to the size and temperature of our current universe. Earth formed around 4-5-4.6 bya.

Your personal notes, summary of the lesson, and/or questions that you may have:

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Compounds in the Primitive AtmosphereCompound Elements Present Molecular

Formulamethane carbon, hydrogen CH4

ammonia nitrogen, hydrogen NH3

hydrogen hydrogen H2

water hydrogen, oxygen H2Ocarbon dioxide carbon, oxygen CO2

Formation of the Oceans

1) Tremendous amounts of hydrogen and oxygen were trapped below the crust. These elements combined to form water vapor, which was released to the atmosphere.

2) The water vapor condensed in the atmosphere and rained down to form vast oceans.

Sequence of Conditions on Primitive Earth:

1) Heavy particles such as iron, copper and nickel were pulled to the center of the earth.

2) Lighter particles such as helium and hydrogen remained at the surface.

3) Radioactive material and great pressure kept the center of the earth in a molten state.

4) Over a period of years, the outer surface or crust of the earth formed over the molten center (4 BYA).

5) As the outside of the earth cooled, hot gases from the interior escaped to form the primitive atmosphere.

Label the following in the diagram below: He, Ni, Cu, Fe, H2

What major gas, necessary for life, is missing from the atmosphere

of primitive Earth? _______________

Look at the pictures of Primitive Earth and ModernEarth to the right

What are the similarities between Primitive Earth andModern Earth? __________________________________________________________________________________________________________________________________________________

What are the differences between Primitive Earth andModern Earth? ______________________________________________________________________________________________________________________________________________________________________________________

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Two major differences between primitive Earth and modern earth set the stage for the formation of organic compounds (hydrocarbons) and, eventually, the origin of living things.

1) Oxygen (O2) – a highly reactive compound. Will break bonds that form between simple organic compounds and destroy them.

2) The atmosphere had abundant energy that could be used to join atoms that form hydrocarbons.a) Lacking an ozone (O3) layer, the atmosphere had

abundant UV radiation.b) Lightening in the atmosphere .c) Heat from volcanoes above and below ocean level

Use your own words to describe the conditions of the early Earth and the early atmosphere.(This is #1 from the checklist on the USG of what you should be able to do by the end of this unit)_______________________________________________

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Theory of Chemical Evolution

In 1924, Alexander Oparin and J.B. Haldane developed a theory for the origin of organic compounds:

1) Inorganic Matter: like CO2 and NH3, (plus organics like CH4) in the atmosphere combined using the energy sources listed above.

2) Simple Organic Molecules: like HCN (hydrogen cyanide) and formaldehyde formed primitive clumps of organic matter.

Use the word bank to fill in the blanks below:

1) CO2, H2 and NH3 are types of ________________ molecules found in the atmosphere on ___________________________.

2) Scientific evidence indicates that organic molecules and cells may have formed _________________ on ancient Earth.

3) The lack of free atmospheric _____________ and the abundance of energy on early Earth facilitated the formation of organic compounds from inorganic __________________________.

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Primitive Earth’s Atmosphere

Conditions on primitive Earth gave rise to simpleorganic compounds, the precursors to life.

precursors, inorganic, spontaneously,oxygen, primitive Earth

In 1953, Stanley Miller and Harold Urey developed a model to test the Oparin/Haldane Hypothesis.

Gases in the apparatus are CH4, NH3, H2O, & H2

Sources of energy: electricity (to represent lightening)

Analysis of substances (organic soup) collected in the trap: HCN (hydrogen cyanide), lactic acid, acetic acid, simple amino acids, formaldehyde.

What would happen if you add O2 to the above mixture?: ____________________________________________________________________________________

Other scientists used UV light in this model and formed simple organic molecules like HCN which can be used to form adenine, a nitrogen base.

Label Miller and Urey’s apparatus using the word bank below:

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Miller and Urey Support theTheory of Chemical Evolution

____________ A

__________B

C__________

D__________

E_______________

organic soup, lightning (electricity), oceans, rainfall, heat source, primitive atmosphere

F__________

Once simple, organic compounds were formed, polymers of carbohydrates, proteins, lipids and nucleic acids could give rise to protocells. Protocells: simple precursors to cells then evolved into primitive cells with RNA as the genetic material.

simple organic compounds polymers protocells primitive cells

Were the first primitive cells autotrophs or heterotrophs?

1) Heterotroph : an organism which requires an external supply of energy in the form of food as it cannot make (synthesize) its own.

2) Autotroph : an organism that produces complex organic compounds from simple inorganic molecules using energy from light (by photosynthesis) or inorganic chemical reactions.

Which form of life – autotrophic or heterotrophic – is a simpler design? Explain._______________________________________________

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Forms of Cellular Respiration

1) Aerobic Respiration : form of cellular respiration that requires oxygen

2) Anaerobic Respiration : form of cellular respiration that does not require oxygen

Which form of cellular respiration was used by the first organisms? Why?_______________________________________________

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The Heterotroph Hypothesis

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Anaerobic heterotrophs consumed organic matter (organic “soup”) and underwent anaerobic respiration.

The first autotrophs: 2.5 bya – primitive cyanobacteria – blue green algae

Photosynthesis provide two important things:

1) a source of food for heterotrophs

AND

2) free oxygen for the environment and aerobic respiration

The evolution of O2-producing autotrophs transformed Earth's atmosphere to one suitable for the evolution of aero-bic metabolism and complex life

Weigh the significance of the evolution of autotrophs in changing the conditions on early earth.(This is #7 from the checklist on the USG of what you should be able to do by the end of this unit)

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The effects of photosynthesis on the development of the ozone layer:

1) some of the O2 formed by producers is used to form the ozone layer

O2 + UV light O3

2) ozone blocks most ultraviolet (UV) radiation from reaching the Earth

3) One source of energy for formation of organic compounds is reduced, BUT

Organisms exposed to the atmosphere are not harmed by the UV radiation

4) O2 becomes available for aerobic cellular respiration

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By studying fossil records, we can determine the occurrence of different types of organisms.

Time from the Present First Records of: 4.5 BYA origin of the Earth *3.8 – 3.5 BYA prokaryotic heterotrophs *2.5 – 3 BYA prokaryotic autotrophs, first Evidence of photosynthesis 1.5 BYA unicellular eukaryotes 650 million years ago multicellular eukaryotes 400 million years ago plants invade the land 300 million years ago animals invade the land 200 million years ago first mammals 150 million years ago first dinosaurs 100 million years ago last dinosaurs *100,000 years ago human development

Based on the following information and the geological “clock”, label the outside of the clock with the occurrence of each type of organism listed.

Geological Clock

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Evidence About the Past

3 Domain and Kingdom System of Classification

1) Label the kingdoms as eukaryotic or prokaryotic.

2) Label the kingdoms as unicellular, multicellular, or both.

3) Label the kingdoms as heterotrophic, autotrophic, or both.

4) Did the Fungi evolve from Plants? ________

5) Are Protists the ancestors of Animals? ________

6) Are Archaebacteria the ancestors of Eubacteria? ___

7) Did plants evolve from Protists? _______

Diversity of Life

Archaebacteria Eubacteria Protista Animalia Fungi Plantae

Eukaryotic

Prokaryotic

Unicellular

Multicellular

Both Uni&Multi

Heterotrophic

Autotrophic

Both Hetero&Auto 8

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