The Chemistry of Biology Practice Test

Post-transcriptional regulation is control that happens after an mRNA has been made, shaping how much protein is produced. This includes processes like mRNA splicing, polyadenylation, export from the nucleus, changes in mRNA stability, localization, and, crucially, how efficiently the mRNA is translated. For example, microRNAs can bind to mRNA to block translation or promote decay, reducing protein output without changing the transcription rate. In contrast, transcriptional regulation acts at the level of RNA synthesis, DNA replication control pertains to copying DNA rather than gene expression, and protein degradation is a post-translational step that affects protein levels after translation. So describing regulation that occurs after transcription aligns with post-transcriptional regulation.