BIO152H5 Chapter Notes - Chapter 15: Reading Frame, Meiosis, Chromosomal Translocation
Document Summary
Mendel discovered that alleles don"t change when transmitted from parent to offspring. Beadle said one ought to be able to discover what genes do by making them defective . Idea was to knock out a gene by damaging it and then infer what the gene does by observing the phenotype of the mutant individual. Today, genes that don"t function at all are called knock-out, null or loss-of-function alleles. Beadle and tatum exposed n. crassa cells to radiation and examined. Proposed that the mutant n. crassa individual could not make pyridoxine because it lacked an enzyme required to synthesize the compound and the lack of the enzyme was due to a genetic defect. Concluded each gene contains the info needed to make an enzyme. Genetic screen: any technique for picking certain types of mutants out of many thousands of randomly generated mutants. Genes dictate the structures of all the proteins produced by an organism--- not just the structures of enzymes.
