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Unformatted text preview: This lecture will be covered on Exam 3 In 1902, Archibald Garrod provided the first clue in the mystery of how genes work through his study of alkaptonuria , a disease in which homogentisic acid is secreted in the urine. Garrod hypothesized that the metabolic pathway in which homogentisic acid is an intermediate must be blocked in alkaptonurics ( Figure 15.1 ). This block must be due to lack of an enzyme that breaks down homogentisic acid, leading to its buildup. George Beadle and Edward Tatum developed the one-gene, one-enzyme hypothesis , which states that each gene carries the information for one protein or enzyme. Adrian Srb and Norman Horowitz then published a rigorous test of the one-gene, one- enzyme hypothesis that focused on the ability of the bread mold Neurospora crassa to synthesize the amino acid arginine ( Figure 15.2 ). RNA polymerase is the enzyme that synthesizes mRNA by reading DNA sequences. RNA polymerase transcribes one strand of the DNA, making a complementary RNA copy according to the rules of complementary base pairing ( Figure 15.5 ). George Gamow predicted that each word ( codon ) in the genetic code the rules that specify the relationship between a sequence of nucleotides in DNA or RNA and the...
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This note was uploaded on 12/06/2009 for the course BIO 225 taught by Professor Pavgi during the Spring '08 term at University of Michigan.
- Spring '08