Sequence of RNA nucleotides bound to a region of single-stranded DNA to initiate DNA replication?

• A. RNA Primer
• B. RNA Transcript
• C. DNA Primer
• D. Primase

Answer: (A)

RNA primer is the short sequence of RNA nucleotides that binds to the single-stranded DNA to start replication. DNA polymerases can’t begin a new strand on their own—they require a free 3’ OH to add nucleotides. Primase creates this short RNA primer opposite the DNA template, giving the replication machinery a starting point. Once the primer is in place, DNA polymerase can extend the new strand by adding DNA nucleotides. Later, the RNA primer is removed and replaced with DNA. This is different from an RNA transcript, which is produced during transcription, and from a DNA primer, which would be DNA rather than RNA and isn’t what initiates replication.