BIOLOGY 1A03 Lecture Notes - Lecture 10: Ribosome, Methionine, Alternative Hypothesis

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Daniel Yang

Document Summary

One gene and one enzyme hypothesis proposed by beadle and tatum. Predicts that knockout of genes would lead to loss of enzymes required for synthesizing a particular product such as arginine. Based on analyses of knock-out mutants, the one-gene one-enzyme hypothesis claimed that genes contain the information needed to make proteins, many of which function as enzymes. Mutagenesis: application of high-energy radiation to create a large number of n. crassa mutants. Genetic screens: grow these mutants in normal media that lack arginine but are supplemented with nothing, arginine, citrulline, or ornithine. Fig 15. 2 - experimental support for the one-gene, one-enzyme hypothesis. Focused on the ability of n. crassa to synthesize arginine. Organisms synthesize arginine via a metabolic pathway. Ornithine and citrulline act as intermediates in metabolic pathway leading to arginine. Used radiation to create large number of mutant individuals; it was likely that a handful of n. crassa contained knock-out mutations in pathway for arginine synthesis.