01:119:115 Lecture Notes - Lecture 15: Archibald Garrod, Neurospora Crassa, Messenger Rna
2 May 2016
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Lecture 15: gene expression: 17. 1-17. 4 10/21/14: relationship between genes and proteins. Dna (cid:0) synthesis of proteins (cid:0) specific traits. Gene expression = process by which dna directs protein synthesis. Includes two stages: transcription, translation, garrod showed: genes are responsible for phenotypes. George beadle and edward tatum (1920s) neurospora crassa (cid:0) bread mold wild type: live on minimal medium ( few nutrients) bombarded with x-rays (cid:0) genetic changes (cid:0) mutations (cid:0) unable to produce particular enzymes nutritional mutants. Relationship between genes and enzyme (cid:0) one gene (cid:0) on enzyme hypothesis: each gene dictates production of specific enzyme. Now know that not all proteins are enzymes (cid:0) one gene(cid:0) one protein (actually polypeptide: flow of genetic information. Central dogma of molecular biology in prokaryote: translation begins before transcription has finished in eukaryotic (cid:0) nuclear envelope + rna processing: rna composition and types. Rna = ribonucleic acid --> nucleic acid as in dna uracil (u) pyrimidine --> substitutes for thymine --> u =a.
