Both repressible and inducible operons control gene expression at the level of __________.

• A. DNA packing
• B. post-transcriptional processing
• C. translation
• D. post-translational processing
• E. transcription

Answer: (E)

Verified step by step guidance

1. Understand the concept of operons: Operons are clusters of genes regulated together, typically found in prokaryotes. They consist of structural genes, a promoter, and an operator. The regulation of these genes is crucial for efficient cellular function.
2. Differentiate between repressible and inducible operons: Repressible operons are typically active and can be turned off when a specific molecule is present. Inducible operons are usually inactive and can be turned on in the presence of a specific molecule.
3. Identify the level of gene expression control: Gene expression can be regulated at various stages, including transcription, translation, and post-translational processing. Operons primarily control gene expression at the transcription level.
4. Explore transcription regulation: Transcription is the process of copying a segment of DNA into RNA. Operons regulate whether transcription occurs, thus controlling the production of mRNA and subsequently the synthesis of proteins.
5. Conclude the role of operons: Both repressible and inducible operons control gene expression by influencing the transcription process, determining whether the genes within the operon are transcribed into mRNA.