The main enzyme involved in transcription is RNA polymerase.

What enzyme is involved in transcription?

Transcription is the process of copying a DNA sequence into an RNA molecule, usually mRNA, as the first step in gene expression. The key enzyme that does this is RNA polymerase, sometimes called DNA‑dependent RNA polymerase because it uses DNA as a template to build RNA.

In simple terms:

  • RNA polymerase binds to a specific DNA region called the promoter.
  • It unwinds a small stretch of the DNA double helix.
  • Using one DNA strand as a template, it links RNA nucleotides together to form a complementary RNA strand, in the 5' → 3' direction.
  • When it reaches a terminator sequence, it stops and releases the newly made RNA.

In eukaryotes (like humans), there are multiple RNA polymerases with specialized roles: RNA polymerase I, II, and III, which transcribe different types of RNA (rRNA, mRNA, tRNA, etc.). In many biology exam questions, when they ask “what enzyme is involved in transcription?”, the expected one-word answer is RNA polymerase.

So if you’re answering a quick quiz or test:
Transcription enzyme = RNA polymerase. ✅

TL;DR: The enzyme involved in transcription is RNA polymerase, which reads DNA and builds a complementary RNA strand.

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