Which of the following is an example of positive regulation of gene expression?

• A. Transcription is halted on a specific gene to limit the amount of protein being created by the gene's expression.
• B. The protein that is translated is immediately degraded by the cell before it can serve its function.
• C. Elongation of translation comes to a stop and the ribosome dissociates when a regulatory protein binds.
• D. A protein binds to DNA and then stimulates the initiation of transcription of a specific gene.

Answer: (D)

Verified step by step guidance

1. Understand the concept of gene expression regulation: Gene expression can be regulated at various stages, including transcription, translation, and post-translation. Positive regulation involves mechanisms that increase the expression of a gene.
2. Identify the key feature of positive regulation: In positive regulation, a regulatory protein (often called an activator) binds to a specific site on the DNA, enhancing the transcription of the gene.
3. Analyze the options given: Each option describes a different scenario of gene expression regulation. Look for the one that involves an increase in gene expression due to a regulatory protein.
4. Evaluate the correct option: The option stating 'A protein binds to DNA and then stimulates the initiation of transcription of a specific gene' describes a scenario where a protein (activator) enhances transcription, which is characteristic of positive regulation.
5. Conclude the analysis: The correct example of positive regulation is when a protein binds to DNA and stimulates transcription, as this increases the gene's expression.