Transcription is an important step in making proteins. During this process, genetic information from DNA is copied into RNA. Three main types of enzymes help with this: RNA polymerase, transcription factors, and helicase.

1. RNA Polymerase

• What it does: RNA polymerase is the main enzyme that helps create RNA from the DNA. It links together building blocks of RNA called ribonucleotides.
• How it works: This enzyme adds these building blocks to the growing RNA strand in a specific direction (from the 5' end to the 3' end), following the DNA strand like a guide.
• Types: In cells with a nucleus, there are three main types of RNA polymerases:
  • RNA Polymerase I: Makes rRNA (except for a small part called 5S rRNA) and works at about 250–300 building blocks per minute.
  • RNA Polymerase II: Makes mRNA and some small RNA and works at about 20–30 building blocks per second.
  • RNA Polymerase III: Makes tRNA and 5S rRNA and works at about 100–120 building blocks per second.

2. Transcription Factors

• What they do: These proteins attach to specific parts of DNA and help bring RNA polymerase to the right spot on a gene.
• Types: There are two main types of transcription factors:
  • General transcription factors (GTFs): Needed for copying all protein-coding genes.
  • Specific transcription factors: Help control which genes are expressed by binding to certain regions, helping to influence how much of a gene is used.

3. Helicase

• What it does: Helicase unwinds the double-stranded DNA so that RNA polymerase can access the DNA strand.
• Why it matters: Without helicase, transcription could not happen because the DNA strands need to open up for RNA to be made.

In short, these enzymes work together to make sure transcription happens correctly and quickly. This is crucial because it leads to the production of RNA molecules that are important for making proteins.