BIOL 1107 Chapter Notes - Chapter 18: Metabolic Pathway, Tryptophan, Repressor
Document Summary
Bacteria often respond to environmental change by regulating transcription. E. coli depends on amino acid, tryptophan in order to survive. In erratic environment, activates metabolic pathway makes tryptophan from another compound (enzymes catalyze compound to make amino acid for e. coli) By inhibiting enzyme activity: cells adjust production level of certain enzyme, if environment provides all tryptophan needed cell stops making enzymes to catalyze the making of tryptophan. Regulation of tryptophan synthesis pathway is how bacteria tune metabolism to changing environments. E. coli creates amino acid tryptophan from precursor molecule in three step pathway. Each reaction in pathway is catalyzed by specific enzyme. Long mrna codes for 5 polypeptides making up enzyme in tryptophan pathway. Cell can translate one mrna into 5 separate polypeptides. Mrna has start and stop codons signal where each polypeptide begins and ends. Controls access of rna polymerase to genes. With promoter or between promoter and enzyme-coding genes.
