Which type of mutations primarily affect transcription versus translation?

• A. Promoter/regulatory mutations affect transcription; coding region or splice-site mutations affect translation or processing
• B. Frameshift mutations
• C. Silent mutations
• D. Nonsense mutations

Answer: (A)

Mutations that affect transcription are usually located in promoter or regulatory regions that control when and how much mRNA is produced. When such mutations occur, the level of transcription changes, altering gene expression at the transcription stage. In contrast, mutations that influence translation or RNA processing come from changes in the coding sequence or in splice sites. Coding region mutations can change the amino acid sequence or cause frameshifts, directly impacting how the protein is produced during translation, while splice-site mutations disrupt RNA splicing and thus the mature mRNA that gets translated. This pairing—promoter/regulatory mutations with transcription and coding-regional or splice-site mutations with translation or processing—captures the primary effects of these mutation types. Frameshift mutations mainly disrupt translation downstream of the mutation, silent mutations often do not alter the protein or transcription, and nonsense mutations affect translation termination, not transcription.