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BIO190: The Class: Origin of Life: Lesson 3

The Origin of Life

The earth is about 4.5 billion years old. The oldest fossils yet discovered located in Western Australia are approximately 3.5 billion years. Charles Darwin called the origins of life and species, the "mystery of mysteries"

Commonalities (shared components) of life forms

Review chapter 2

These commonalities suggest life had common beginning. Scientists do not know how life originated on earth.

-Nucleotides of DNA/RNA

-20 amino acids

-Metabolic pathways

-History of our knowledge about the origin of life

    1. van Helmont
    2. Redi
    3. Needham
    4. Spallanzani
    5. Pasteur (fig. 3-1 & 3-2)
    6. Oparin
    7. Haldane
    8. Miller/Urey

Primitive Earth Characteristics (fig. 3-3)

According to the big bang model, the universe originated from a primeval fireball and has been expanding and cooling since its inception 10 to 20 billion years ago.

For more information browse theses sites:

Creation of the Universe
Birth of the Earth

-Primeval atmosphere

-Appearance of oxygen

Chemical Evolution

All of the current hypotheses for the origin of life require that a variety of carbon compounds be accumulated on earth during a period of prebiotic chemical evolution.

For more information visit this site:

Chemical Aspects of Life

-Sources of energy (tab. 3-1)

(consider also hydrothermal vents: p. 34)

-Prebiotic synthesis of small organic molecules

-Miller/Urey Experiment (fig. 3-4)

Visit this site: The Miller Experiment

-Formation of polymers (fig. 3-5)

Origin of Living Systems

The origin of the earliest life form can be estimated at about 4 billion years ago.

-Origin of metabolism

(example: enzyme mediated reactions)

    1. primary heterotrophs
    2. autrotrophs (fig. 3-6)
    3. heterotrophs (fig. 3-6)

-Appearance of photosynthesis/oxidative (aerobic) metabolism

Precambrian Life

(see inside back cover of text)

-Prokaryote appearance (fig. 3-7)

(nucleoid)

Appearance of Eukaryotes (fig. 3-7)

The eukaryotes ("true nucleus") have cells with membrane bound nuclei containing chromosomes composed of chromatin.

Once you have completed the lesson, you should go to Assignment 3-1.

E-mail Sylvester Allred at Syl.Allred@nau.edu

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