# Transcription

Making an RNA copy of a gene. RNA polymerase binds a promoter, unwinds the DNA and builds messenger RNA (mRNA). In RNA, uracil (U) replaces thymine (T).

Biology (university) · Part 04: DNA, transcription and translation · Card 5 of 9 · Last updated 2026-10-19

## Analogy

Copying one recipe from the book onto a card you can take to the kitchen.

## Example

**Transcribe it**

DNA template: T A C G G T
mRNA:         A U G C C A
U pairs with A.
T is not used in RNA.

## In practice

The template strand ATGC is transcribed into the mRNA UACG.

## Practice

### Flashcards

- **Which enzyme carries out transcription?** RNA polymerase.

### Interview questions

**Explain how the information in a gene becomes a protein in a eukaryotic cell.**

- Transcription in nucleus makes pre-mRNA
- Splicing removes introns, cap and tail added
- mRNA exits to cytoplasm
- Ribosome reads codons with tRNA
- Amino acids joined and folded

## Questions people ask

### How does RNA polymerase know where to start?

It recognises a promoter, a DNA sequence just before the gene. In eukaryotes, helper proteins called transcription factors bind first and then recruit the polymerase. A terminator sequence or signal at the end of the gene tells the enzyme where to stop and release the RNA.

### What is the difference between DNA and RNA?

RNA is usually single-stranded, uses ribose sugar instead of deoxyribose, and has uracil in place of thymine. It is also shorter-lived. These features suit its role as a temporary working copy, while DNA is the stable long-term store of information.

## Related concepts

- [Central dogma](https://studyvisually.com/learn/science/biology-university/biology-university-part-4/biology-university-part-4-concept-4)
- [RNA splicing](https://studyvisually.com/learn/science/biology-university/biology-university-part-4/biology-university-part-4-concept-6)
- [Translation](https://studyvisually.com/learn/science/biology-university/biology-university-part-4/biology-university-part-4-concept-8)
- [Genetic code](https://studyvisually.com/learn/science/biology-university/biology-university-part-4/biology-university-part-4-concept-7)

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