In terms of lac operon regulation, what happens when E. coli is grown in medium containing no glucose but abundant lactose

Lactose is necessary for transcription process.

Explanation:

When there is no lactose provided to the E.coli molecule then the lac repressor cling to the operator, and it prevents the transcription process conducted by the RNA polymerase enzyme. But in the presence of lactose the lac repressor does not bind to the operator which allows the RNA polymerase to actually transcribe the lac operon.

the backbone of the dna and rna compound is sugar phosphate.