Operons are bacterial. Eukaryotic genes work differently
- The idea
- Predict
- See it
- Why
- Check
The idea
“A human gene has an operator like the lac operon, and an operon makes one mRNA per gene.”
The lac operon is often the first gene switch you learn, so it's easy to assume every gene works that way.
The short version
The mistake: A human gene has an operator like the lac operon, and an operon makes one mRNA per gene.
What's actually true: An operon puts several bacterial genes under one promoter and operator, in one mRNA. Each eukaryotic gene makes its own mRNA.
- An operon is a cluster of bacterial genes under one promoter and operator. A repressor on the operator blocks RNA polymerase for all of them.
- Eukaryotic genes have no operators. Each has its own promoter and mRNA. Transcription factors at control elements and enhancers set its level.
On the exam: Operators and one mRNA for several genes belong to bacterial operons. Eukaryotic genes have neither.