How do the chemical modifications described in the passage differ from eukaryotic post-transcriptional modifications?
1) Post-transcriptional modifications are made to mRNA, whereas post-translational modifications only affect enzymes.
2) Post-transcriptional modifications are not catalyzed by enzymes.
3) Post-transcriptional modifications do not involve the addition or removal of parts of the substrate.
4) Post-transcriptional modifications are carried out entirely within the nucleus.