The major difference in RNA processing between prokaryotes and eukaryotes is the processing of messenger RNAs. Eukaryotes splice mainly protein-coding messenger RNAs and some non-coding RNAs. Transcription occurs in the nucleus and does not occur simultaneously with translation. In prokaryotic cells, transcription takes place in the cytoplasm (in tRNAs and non-coding RNAs) and at the same time as translation.