Chapter 26

Chapter 26 - Chapter 26 26.1 The earth's age is said to be...

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Chapter 26 26.1 The earth’s age is said to be 4.6 billion years. It took hundred millions of year before the earth’s able to support life. There were experiments set up to imitate the early earth condition and how life could have started. One theory believes that life could have started from extraterrestrial sources. The first sign of life could have been the protobionts which qualified the two properties of accurate replication and metabolism. The first genetic material were believe to be RNA. Protein synthesis were carried out by a catalysts called ribozymes. Simple virus like RNA molecules evolved to more complex RNA and eventually became the template on which DNA nucleotides were assembled. 26.2 How Rocks and Fossils Are Dated Fossils that are found in sedimentary rocks are important in providing us with the relative ages of the times when these organisms existed by comparing stratum deposited. This method does give us the order in which the fossils were laid down, and often have gaps in the sequence. Another way scientists use to determine a more accurate date is called absolute dating. This method involves using radiometric dating of decaying radioactive isotopes. It’s possible to determine the age of certain fossils by the concept of a fixed half-life of certain isotopes. Common isotopes used are carbon12, carbon14, and Potassium40. Another way of obtain dating information is by the magnetism of rocks. This involve iron particles align themselves with earth’s magnetic field.
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This note was uploaded on 04/12/2008 for the course SCIE 101 taught by Professor Nader during the Spring '08 term at Clemson.

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Chapter 26 - Chapter 26 26.1 The earth's age is said to be...

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