How could antisense RNA be used as an antibiotic? What types of genes would you target using this scheme?

The function of tRNA synthetases is to attach amino acids to tRNAs. Suppose the tRNA synthetase responsible for attaching tryptophan to tRNA is mutated in a bacterial strain, with the result that the tRNA synthetase functions at about 15% of the efficiency of the wild-type tRNA synthetase. Would formation of the 3–4 stem-loop structure in mRNA be more frequent or less frequent in the mutant strain than in the wild-type strain? Why?

The following hypothetical genotypes have genes A, B, and C corresponding to lacI, lacO, and lacZ, but not necessarily in that order. Data in the table indicate whether β-galactosidase is produced in the presence and absence of the inducer for each genotype. Use these data to identify the correspondence between A, B, and C and the lacI, lacO, and lacZ genes. Carefully explain your reasoning for identifying each gene.

The function of tRNA synthetases is to attach amino acids to tRNAs. Suppose the tRNA synthetase responsible for attaching tryptophan to tRNA is mutated in a bacterial strain, with the result that the tRNA synthetase functions at about 15% of the efficiency of the wild-type tRNA synthetase.

How would this mutation affect attenuation of the tryptophan operon? Explain your answer.

For an E. coli strain with the lac operon genotype I⁺ P⁺ O⁺ Z⁺ Y⁺, identify the level of transcription of the operon genes in each growth medium listed. Specify transcription as 'none,' 'basal,' or 'activated' for each medium, and provide an explanation to justify your answer.

Growth medium contains glucose but no lactose.

For an E. coli strain with the lac operon genotype I⁺ P⁺ O⁺ Z⁺ Y⁺, identify the level of transcription of the operon genes in each growth medium listed. Specify transcription as 'none,' 'basal,' or 'activated' for each medium, and provide an explanation to justify your answer.

Growth medium contains lactose but no glucose.

For an E. coli strain with the lac operon genotype I⁺ P⁺ O⁺ Z⁺ Y⁺, identify the level of transcription of the operon genes in each growth medium listed. Specify transcription as 'none,' 'basal,' or 'activated' for each medium, and provide an explanation to justify your answer.

Growth medium contains lactose and glucose.