Chapter 21 The Origin

Chapter 21 The Origin - Chapter 21 The Origin Evolution of...

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I. Life Begins A. Evolution of life has been linked, from its origin to the present, to the physical and chemical evolution of the earth. B. Origin of Life 1. Early Earth and Its Atmosphere a. Planets formed about 4.6 billion years ago. b. By 4 billion years ago, the earth’s atmosphere (no oxygen) was forming, liquid water was being retained by gravity, and primitive living cells were emerging. c. Is it possible to devise experiments that would test whether life could have originated spontaneously under primitive earth conditions? 2. Synthesis of Biological Molecules a. Components for building biological molecules accumulated in the primitive earth; and energy (lightning, heat) was present. b. Stanley Miller used a lab apparatus to demonstrate synthesis of amino acids from hydrogen, methane, ammonia, and water under abiotic conditions. 3. Self-Replicating Systems
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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Chapter 21 The Origin - Chapter 21 The Origin Evolution of...

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