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Unformatted text preview: Chapter 15: How Genes Work Key concepts: 1. Most genes code for proteins 2. DNA is transcribed to mRNA by RNA polymerase, and then messenger RNA is translated to proteins by ribosomes. In this way, genetic info is converted from DNA to RNA to proteins. 3. Each amino acid in a protein is specified by a group of three bases in mRNA 4. Mutations are random changes in DNA, ranging from single bases to large chromosome regions, that may or may not produce changes in the phenotype • gene expression- the process of converting archived info into molecules that do things in the cell • alleles that do not function are called knock out, null, or loss of function alleles • creating knock out mutant alleles and analyzing their effects is the most common research strategies in studies of gene function • one gene, one enzyme hypothesis- the hypothesis that each gene is responsible for making one (and only one) protein, in most cases an enzyme that catalyzes a specific reaction. Many exceptions to the hypothesis are known. • Srb and Horowitz studied N. crassa individuals to synthesize the a.a. arginine. • Studied the metabolic pathway • Genetic screen- any technique for picking certain types of mutants out of many thousands of randomly generated mutants • Crick was proposing that different combinations of bases could specify the 20 amino...
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- Fall '11