Question

The list of events below describes the processing of ribosomal RNAs. Please select the choice that lists the events in correct sequential order.

1. Methyl groups are added to specific bases and the 2′-carbon atom of some ribose sugars
2. Transcription of the rRNA precursors from DNA
3. Cleavage of precursor rRNA
4. Individual rRNA molecules ready for ribosome assembly
5. Trimming of precursor rRNA
1) 3, 1, 2, 5, 4
2) 2, 3, 4, 5, 1
3) 4, 2, 3, 1, 5
4) 1, 3, 5, 4, 1
5) 2, 1, 3, 5, 4

Answer 1

The correct order for the processing of rRNAs is transcription from DNA, addition of methyl groups, cleavage, trimming, and then the rRNAs are ready for assembly, which corresponds to option 5) 2, 1, 3, 5, 4.

Step-by-step explanation:

The correct sequence for the processing of ribosomal RNAs (rRNAs) is initiated by the transcription of the rRNA precursors from DNA. This is followed by modifications such as the addition of methyl groups to specific bases and the 2'-carbon atom of some ribose sugars. After these modifications, the precursor rRNA undergoes cleavage, and then the rRNA is further trimmed. Finally, the individual rRNA molecules become ready for ribosome assembly.

1. Transcription of the rRNA precursors from DNA
2. Methyl groups are added to specific bases and the 2'-carbon atom of some ribose sugars
3. Cleavage of precursor rRNA
4. Trimming of precursor rRNA
5. Individual rRNA molecules ready for ribosome assembly

Therefore, the correct sequence of events as listed in the options provided by the student is option 5) 2, 1, 3, 5, 4.