Biology Chapter 26 Objectives

Biology Chapter 26 Objectives - Chapter 26 The Tree of...

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Chapter 26 The Tree of Life: An Introduction to Biological Diversity The Origin of Life 1. The four stages of the hypothesis for the origin of life on Earth by chemical evolution are: (1) the abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nucleotides; (2) the joining of these small molecules (monomers) into polymers, including proteins and nucleic acids; (2) the packaging of these molecules into “protobionts,” droplets with membranes that maintained an internal chemistry different from that of their surroundings; and (4) the origin of self-replicating molecules that eventually made inheritance possible. 2. A. I. Oparin and J. B. S. Haldane independently postulated that Earth’s early atmosphere had been a reducing (electron-adding) environment, in which organic compounds could have formed from simple molecules. The energy for this organic synthesis could have come from lightening and intense UV radiation. Stanley Miller tested the tested the Oparin-Haldane hypothesis by creating laboratory conditions comparable to those that the scientists at the time thought existed early on Earth. The apparatus yielded a variety of amino acids found in organisms today, along with other organic compounds. Most of the chemical reactions probably occurred in the atmosphere, and small “pockets” of the early atmosphere were reducing. The first organic compounds on Earth may have also been synthesized near submerged volcanoes and deep-sea vents. 3. There is a lot of evidence that suggests that RNA was the first genetic material since it can carry out a number of enzyme-like catalytic functions. Ribozymes are DNA catalysts. Some ribozymes can make complementary copies of short pieces of RNA. Others can remove segments of themselves or can act on different molecules, excising pieces of these molecules and making them fully functional.
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This note was uploaded on 08/29/2009 for the course BIOL 101 taught by Professor Sakji during the Fall '08 term at Linn Tech.

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Biology Chapter 26 Objectives - Chapter 26 The Tree of...

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