If a cell mistakenly transcribed and translated a gene's intron, the most likely outcome would be that additional amino acids would be inserted into the chain. This is because introns are non-coding regions of DNA that are usually removed during RNA splicing before translation. If an intron is included in the mature mRNA and subsequently translated, it could lead to a protein with an inappropriate sequence and additional amino acids that could disrupt the protein's function, potentially resulting in a nonfunctional or malfunctioning protein.
The other options you listed would not occur:
- The DNA would remain the same because the presence of the intron in transcription would not change the underlying DNA sequence.
- While errors in protein folding might happen, they wouldn't be "repaired" in a direct sense; instead, the improperly formed protein might be tagged for degradation.
- The idea that the intron would begin to duplicate itself is misleading; introns don’t replicate themselves as part of transcription and translation processes.
In summary, if an intron was mistakenly included in translation, the primary consequence would involve the incorporation of additional, unintended amino acids into the resulting polypeptide.