試題詳解

24. In eukaryotic cells,_________.
(A) gene expression is regulated mostly at the level of transcription
(B) all mRNAs tend to remain stable for about the same length of time
(C) mRNA activity is altered through modifications such as phosphorylation
(D) promoters are typically "on" in the absence of regulatory proteins
(E) genes involved in similar processes are clustered together in operons