Which of the following statements correctly describes the primary difference between enhancers and proximal control elements?

• A. Enhancers are transcription factors; proximal control elements are DNA sequences.
• B. Enhancers increase transcription of specific genes; proximal control elements inhibit transcription of specific genes.
• C. Enhancers are located thousands of nucleotides away from the promoter; proximal control elements are close to the promoter.
• D. Enhancers are DNA sequences; proximal control elements are transcription factors.

Answer: (C)

Verified step by step guidance

1. Understand the role of enhancers and proximal control elements in gene expression. Enhancers are DNA sequences that can increase the transcription of specific genes by interacting with transcription factors.
2. Recognize that enhancers can be located far from the promoter region of a gene, sometimes thousands of nucleotides away, yet still influence transcription by looping the DNA to bring the enhancer in proximity to the promoter.
3. Identify proximal control elements as DNA sequences that are located close to the promoter region of a gene. These elements are crucial for the regulation of transcription initiation.
4. Differentiate between enhancers and proximal control elements based on their location relative to the promoter. Enhancers can be distant, while proximal control elements are near the promoter.
5. Conclude that the primary difference between enhancers and proximal control elements is their location relative to the promoter, with enhancers being potentially far away and proximal control elements being nearby.