How can mutations in DNA affect transcription and translation?

• A. They can alter promoter strength or transcription factor binding, modify coding sequences affecting translation, or create premature stop codons or frameshifts.
• B. They only affect the amino acid sequence; transcription is unchanged.
• C. They always enhance transcription while not affecting translation.
• D. They only affect mRNA stability and not protein.

Answer: (D)

Mutations can affect the flow of genetic information at several points, influencing both transcription and translation through changes to regulatory regions, coding sequences, and RNA features. In transcription, a mutation in a promoter or enhancer can alter how strongly RNA polymerase and transcription factors bind, changing how much mRNA is produced. Splice-site mutations or those at other regulatory elements can produce abnormal transcripts that are unstable or faulty. In translation, coding-sequence changes can alter the amino acid sequence, create a premature stop, or cause a frameshift, leading to a nonfunctional or truncated protein. Variants in untranslated regions can impact translation efficiency and mRNA stability by changing ribosome access or interactions with regulatory proteins or microRNAs. Overall, mutations can modify how much protein is made and what that protein ends up like, through effects on transcription, RNA processing and stability, and translation.