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 1. Molecular clocks use mutations to estimate evolutionary time

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PostSubject: 1. Molecular clocks use mutations to estimate evolutionary time   04/02/09, 10:45 pm

• 1960’s- Linus Pauling and Emile Zuckerlandl found new way to measure evolutionary time by comparing amino acid sequences of hemoglobin and finding a mutation rate

MOLECULAR EVOLUTION
• Molecular clocks- models that use mutation rates to measure evolutionary time
• (Remember- mutations are nucleotide substitutions in DNA, some of which cause amino acid substitutions in proteins)
• Related species mutate at the same pace. EX- one mutation per ten million years
• More time has passed = more different the two will be at a molecular level

LINKING MOLECULAR DATA WITH REAL TIME
• To estimate mutation rates, you must find links between molecular data and real time
• Often a geologic event that separated the species you are studying
EX- Australia and South America broke up, so the organisms on both parts started to diverge from each other
• The link can come from fossil evidence
• Pauling and Zuckerlandl compared their molecular data with the first appearance of each type of organism in the fossil record
• They confirmed that the number of amino acids differences increased with the evolutionary time of that group of species.
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