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Multiple Choice
Which statement best describes an operon in prokaryotic gene regulation?
A
An operon is a cluster of genes under the control of a single promoter and regulated together.
B
An operon is a single gene that codes for multiple unrelated proteins.
C
An operon is a segment of eukaryotic DNA that contains only non-coding sequences.
D
An operon is a regulatory protein that binds to DNA to activate transcription.
Verified step by step guidance
1
Step 1: Understand the concept of an operon. An operon is a functional unit of DNA in prokaryotes that consists of a cluster of genes under the control of a single promoter. These genes are transcribed together as a single mRNA strand, allowing coordinated regulation of their expression.
Step 2: Analyze the options provided in the problem. The correct description of an operon should align with its definition as a cluster of genes regulated together under a single promoter.
Step 3: Eliminate incorrect options. For example, 'An operon is a single gene that codes for multiple unrelated proteins' is incorrect because an operon consists of multiple genes, not a single gene. Similarly, 'An operon is a segment of eukaryotic DNA that contains only non-coding sequences' is incorrect because operons are specific to prokaryotes and include coding sequences.
Step 4: Evaluate the remaining options. The statement 'An operon is a regulatory protein that binds to DNA to activate transcription' is incorrect because an operon is a DNA sequence, not a protein. Regulatory proteins, such as repressors or activators, interact with operons but are not operons themselves.
Step 5: Confirm the correct answer. The statement 'An operon is a cluster of genes under the control of a single promoter and regulated together' accurately describes the structure and function of an operon in prokaryotic gene regulation.