What is transcription?

• A. The synthesis of RNA using a DNA template
• B. The synthesis of DNA using an RNA template
• C. The synthesis of protein from RNA
• D. The replication of the whole genome

Answer: (A)

Transcription is the synthesis of RNA using a DNA template. RNA polymerase binds to a DNA promoter, unwinds the DNA, and reads the template strand to assemble a complementary RNA strand in the 5' to 3' direction, using ribonucleotides. The resulting RNA can be mRNA, rRNA, or tRNA depending on which gene is transcribed, and in eukaryotes many transcripts are processed before becoming functional RNA. This is distinct from other cellular processes: making DNA from RNA is reverse transcription, not transcription; translating RNA into protein is translation; and copying the entire genome is DNA replication.