# "Writing" Life (DD-313)

> Transcription is the first step of gene expression and a major control point for it. It is error-prone compared with DNA copying, needs many helper proteins in complex cells, and is the target of antibiotics such as rifampicin; its molecular basis in eukaryotes earned Roger Kornberg the 2006 Nobel Prize in Chemistry.

- Department: Science
- First published: 2024-08-31
- Last updated: 2024-08-31
- Permalink: https://detailenjoyer.com/case/writing-life/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-313-F01**: Transcription copies DNA into RNA. _(Write-up · Exhibit A (A built-in unzipper))_
- **DD-313-F02**: RNA polymerase does the copying. _(Write-up · Exhibit A (A built-in unzipper))_

## Write-up

Copying a gene into RNA looks simple on a diagram, but it is the point where cells, drugs and even poisons decide which genes get expressed.

1. **A built-in unzipper**: Unlike DNA polymerase, RNA polymerase has its own helicase activity, so no separate enzyme is needed to open the DNA, and the exposed single strand is called the transcription bubble.
2. **Sloppier than replication**: Transcription has some proofreading mechanisms, but they are fewer and less effective than the checks used when DNA itself is copied.
3. **Many helpers in complex cells**: In eukaryotes, RNA polymerase II needs six general transcription factors, TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH, to start transcribing.
4. **A target for drugs**: The antibiotic rifampicin works by binding the beta subunit of bacterial RNA polymerase and blocking transcription.
5. **Nobel-winning detail**: Roger Kornberg won the 2006 Nobel Prize in Chemistry for his studies of the molecular basis of eukaryotic transcription.

## Related case files

- [Rosalind (DD-093)](https://detailenjoyer.com/case/rosalind/): I linked the scientist behind DNA's structure

## Reel vs. record

- **Note**: The Reel calls the mRNA an exact copy of the coding sequence; it matches the coding strand with uracil in place of thymine.

## Video: "Writing" Life: RNA Polymerase Copies a Gene Into Messenger RNA

- Duration: 36.2 s · Published: 2024-08-31
- File: https://detailenjoyer.com/assets/videos/C_Uf8tltMX6.mp4

### Transcript

Did you know DNA transcription is the process by which the genetic information stored in DNA is copied into a complementary RNA strand? This occurs in the cell nucleus, where an enzyme called RNA polymerase binds to a specific region of the DNA known as the promoter. The enzyme then unwinds the DNA helix and reads one strand of the DNA to synthesize a messenger RNA, or mRNA molecule. The sequence of bases in the DNA is used as a template, ensuring that the mRNA is an exact, complementary copy of the DNA's coding sequence. Once the mRNA strand is completed, it detaches from the DNA and exits the nucleus, moving to the cytoplasm, where it will be translated into a protein by ribosomes. NOW YOU KNOW!

## Questions & answers

**Q: Which enzyme transcribes DNA?**  
A: It builds RNA. _(Source: Write-up · Exhibit A (A built-in unzipper) · Wikipedia: Transcription (biology))_

**Q: Where does it bind first?**  
A: A start region. _(Source: Write-up · Exhibit C (Many helpers in complex cells) · Wikipedia: RNA polymerase)_

**Q: What is made?**  
A: mRNA. _(Source: Write-up · Exhibit A (A built-in unzipper) · Wikipedia: Transcription (biology))_

**Q: Where are proteins made?**  
A: In the cytoplasm. _(Source: Write-up · Exhibit B (Sloppier than replication) · Wikipedia: Transcription (biology))_

**Q: What does RNA use instead of thymine?**  
A: U for T. _(Source: Write-up · Exhibit D (A target for drugs) · Wikipedia: Transcription (biology))_

## Sources

- [Wikipedia: Transcription (biology)](https://en.wikipedia.org/wiki/Transcription_(biology))
- [Wikipedia: RNA polymerase](https://en.wikipedia.org/wiki/RNA_polymerase)

## Cite this case file

Easterling, Marcus. ""Writing" Life." The Detail Department (DetailEnjoyer), case file DD-313, last updated Aug 31, 2024. https://detailenjoyer.com/case/writing-life/