Final answer:
Mutant cells with a mutation that eliminates lacI transcription will not produce the lacI repressor protein or mRNA. Despite the presence of high lactose, high levels of glucose typically keep the lac operon repressed, but the absence of the repressor due to the mutation could affect normal regulation. The accurate answer is therefore option 2) The cells will not produce lacI protein.
Step-by-step explanation:
The question pertains to the functioning of the lac operon in E. coli when a mutation eliminates lacI transcription. In this situation, the I gene, which codes for the repressor protein, is not transcribed, and therefore, neither lacI mRNA nor the lacI protein is produced. Since lacI is the gene that codes for the repressor that inhibits the lac operon, these mutant cells will not produce lacl protein, which would normally bind to the operator and repress the lac operon.
In the presence of high levels of lactose, even with high glucose present, the lac operon would typically be deactivated due to the presence of glucose, but because the repressor cannot be produced due to the mutation, the operon may remain unchecked and possibly expressed, possibly leading to expression of the other lac operon genes.
However, the high glucose conditions normally inhibit the expression of the lac operon through cAMP levels and the activity of CAP. Thus, the key point is that the cells will not produce either the repressor mRNA or protein due to the mutation in lace. The accurate answer is therefore option 2) The cells will not produce lacI protein.