Which term describes the DNA sequence at which replication starts?

• A. Origin of Replication
• B. Promoter
• C. Enhancer
• D. Terminator

Answer: (A)

At the heart of this question is where DNA replication starts: a specific sequence called the origin of replication. This site is recognized by initiator proteins that melt the DNA and recruit the replication machinery, establishing replication forks that proceed in both directions to copy the genome. In bacteria there is typically one origin (oriC); in eukaryotes there are many origins to coordinate replication of large genomes. The other terms relate to transcription rather than replication: a promoter is where RNA polymerase binds to begin transcription, an enhancer is a regulatory element that increases transcription levels, and a terminator marks the end of transcription. So the sequence that marks the starting point of replication is the origin of replication.