Define RNA editing and name a common type.

• A. Post-transcriptional modification of RNA bases; A-to-I editing is common (ADAR).
• B. DNA sequence mutation.
• C. Splicing of introns.
• D. Translation of RNA into protein.

Answer: (A)

RNA editing is the process of changing RNA bases after transcription, so the RNA sequence is altered without changing the underlying DNA. A common example is adenosine-to-inosine editing, performed by ADAR enzymes. Inosine is read as guanosine by the cell’s machinery, which can affect which amino acids appear in a protein, influence splicing, or alter RNA structure and interactions with other molecules. This makes the description of post-transcriptional modification of RNA bases with A-to-I editing a precise representation of what RNA editing is. In contrast, a DNA sequence mutation would modify the genome itself, splicing removes introns as part of RNA processing without changing bases, and translation is the process of making proteins from RNA rather than editing the RNA sequence.