A geneticist deletes a 200-bp enhancer 50 kb upstream of a gene. Transcription drops 90% in liver tissue but is unchanged in muscle. The simplest explanation is
- A
The deletion alters the promoter's TATA box recognition sequence
- Bcheck_circle
The enhancer binds liver-specific transcription factors that loop to the promoter
- C
Removing the enhancer shifts the gene's mRNA splicing pattern
- D
The enhancer normally acts as a translation initiation site
Explanation
Enhancers can sit far from promoters and act through DNA looping; tissue-specificity comes from tissue-restricted TFs binding them. Promoter and splicing are physically separate; enhancers are not translated.