What are promoters and which sequence is a common eukaryotic promoter element?

• A. Promoters are DNA regions where RNA polymerase binds to start transcription; the TATA box is a common eukaryotic promoter element.
• B. Promoters are RNA sequences signaling translation termination; poly-A tail is a promoter.
• C. Promoters are proteins that repress transcription; promoter region is the start codon.
• D. Promoters are DNA sequences that terminate replication; origin recognition.

Answer: (A)

Promoters are DNA regions where the transcription machinery binds to start RNA synthesis. In eukaryotes, transcription by RNA polymerase II requires general transcription factors that recognize promoter elements. A well-known promoter element is the TATA box, a short sequence usually about 25–30 bases upstream of the transcription start site, which helps position RNA polymerase II by binding TBP (a component of TFIID) and recruiting the rest of the transcription machinery. Not all genes use a TATA box, but it remains a common promoter element in many eukaryotic genes. The other options mix up concepts—promoters are not RNA sequences signaling translation termination, not poly-A tails, not proteins that repress transcription, and not sequences that terminate replication.