consider e. coli cells that are grown in the presence or absence of the allosteric ligands that regulate the lac and trp operons (lactose and tryptophan, respectively). under each of these conditions, indicate whether the repressor protein (laci or trpr) will be bound to dna or not, and whether the cells will express enzymes encoded by the structural genes in their respective operons (assume no glucose in your lactose experiments).
1. When lactose is present, the repressor protein I [ Select ] ["is not", "is"] bound to the operator sequence and the lac structural proteins [ Select ] ["will", "will not"] be expressed.
2. When tryptophan is absent in the environment, the repressor protein R [ Select ] ["is", "is not"] bound to the operator sequence and the trp structural proteins [ Select ] ["will", "will not"] be expressed.
