A yeast mutant shows decreased expression of the 5.8S rRNA, the 5S rRNA, and protein-encoding mRNAs. If only one gene is mutated, which of the following genes is most likely affected?
A) TATA-binding protein (TBP)
B) Upstream binding factor (UBF)
C) RNA polymerase III
D) TFIIB

Question

Quizplus · Accepted Answer

The TATA-binding protein (TBP) is a component of the transcription machinery for all three types of RNA polymerase in eukaryotes. A mutation in TBP would affect transcription by RNA polymerase I (which transcribes rRNA), RNA polymerase II (which transcribes mRNA), and RNA polymerase III (which transcribes 5S rRNA and other small RNAs), leading to decreased expression of 5.8S rRNA, 5S rRNA, and protein-encoding mRNAs.

A Yeast Mutant Shows Decreased Expression of the 5