Gene Function How does the gene determine the phenotype? Garrold (1902) - alkaptonuria, a human disease, is caused by a recessive gene - homogentistic acid builds up because of a defect in the degradation pathway for phenylalanine (genes effect biochemistry) Beadle and Tatum (1940's) used genetic mutants of neurospora to study biochemical pathways (one gene = one enzyme) Vernon Ingram (1957) used Sanger's technique of fingerprinting peptides to show that a mutant hemoglobin (HbS) differed from the normal hemoglobin (HbA) by the change of one amino acid (one gene = one polypeptide) Charles Yanofsky (1960's) demonstrated that the gene was colinear with the protein he ordered mutations in the A subunit of the tryptophan synthetase gene of E. coli using P1 transduction comparisons of his genetic map with sequences of the mutant proteins showed that the maps were colinear both with respect to order and distance Gene to Protein, How? Crick (1958) proposed that RNA is an intermediate carrier of genetic information needed an intermediate because in eukaryotes the DNA is only in the nucleus while protein synthesis occurs in the cytoplasm proposed ribosomal RNA (rRNA) as the intermediate because it is found with the ribosomes where protein's are synthesized each ribosome would be able to make only one type of protein Jacob, Brenner and Meselson (1961) used T2 phage to show that rRNA was not the carrier of information transient unstable RNA called messenger RNA (mRNA) is the carrier of information Check out this excellant description and animation of the classic experiments that established mRNA as the carrier of the genetic information, from DNA from the Beginning RNA is produced from DNA by a process called transcription [ Biol 207 ] [ Bell ] [ CSU Chico ] [ Library ] This document is maintained by: Jeff Bell Last Update: Friday, April 14, 2000