BIOS 10161 Lecture Notes - Lecture 11: Thalassemia, Zebrafish, Genomics
16 Sep 2016
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Document Summary
Molecular basis for phenotypes was discovered before it was known that dna was genetic material. Studies showed the major phenotypic differences were due to differences in proteins. Model organisms (c eleganssss: easy to grow in lab, short generation times, easy to genetically manipulate, produce large numbers of progeny, ex: drosophilia, zebrafish, mice, and common bread mold neurospora crassa. Neurospora haploid for most of its life cycle, so there are no dominant or recessive alleles. Beadle & tatum used neurospora to test one-gene, one-enzyme hypothesis. X-rays used as mutagen (something that damages dna and causes a mutation heritable alterations in dna sequence) Mutant strains needed additional nutrients to grow, but only required one additional nutrient. Suggested that each mutation caused a defect in only one enzyme metabolic pathway confirmed hypothesis. One gene one enzyme hypothesis has been revised to the one gene, one polypeptide relationship: many proteins have several subunits.
