BIOL 2000 Lecture Notes - Lethal Allele, Auxotrophy, Wild Type
Document Summary
Causes death of the individual when homozygous. The death is usually not noted as it creates an assumption. Changes the mendel 1:3:1 ratio to a 1:2 ratio: ex. Yellow coat in mice is a recessive lethal allele. Yellow x yellow = 1black: 2 yellow: 1 death: ex. Objective 3: understand how beadle and tatum"s experiments led to the idea that multiple genes may control multiple steps in a biosynthetic pathway. Archibald garrod: connected a genetic defect to a defect in chemical reactions in the body. George beadle and edward tatum: one-gene-one-enzyme (polypeptide) model, isolated arginine auxotrophs in neuspora, auxotoph- strain bale to grow only on supplemented media, prototoph (wild type)- able to grow on minimal media, first xrayed to make mutants. Then wild type cross with wild type of opposite mating type grew into fruiting bodies and into microscopic ascospores that were dissected and transferred one by one to culture tubes: plated onto:
