Question

In regards to methylation in both prokaryotes and eukaryotes, will the methyl group be present in the nucleotide precursor found in the cell?

1) Yes
2) No
3) Cannot be determined

Answer 1

Methylation in prokaryotes and eukaryotes occurs post-transcriptionally, where a methyl group is added to specific bases within RNA molecules after they have been transcribed, not in the nucleotide precursors.

Step-by-step explanation:

In terms of methylation in both prokaryotes and eukaryotes, the methyl group is not present in the nucleotide precursors found in the cell. Rather, methylation occurs post-transcriptionally as a modification to specific bases within the RNA. Precursor molecules such as pre-rRNA and pre-tRNA undergo enzymatic cleavage and are subjected to modifications including the addition of a -CH3 (methyl) functional group which adds stability to the molecules.

This process applies to both eukaryotic and prokaryotic cells. In eukaryotic cells, however, additional epigenetic regulation can occur, which includes chemical modifications of DNA or histones, and modifications during RNA processing, making the regulation of gene expression complex.

Answer 2

The methylation process occurs post-transcriptionally, so the methyl group is not present in the nucleotide precursor found in the cell. The correct option is No.

Step-by-step explanation:

The methylation of nucleotides occurs post-transcriptionally; meaning, the methyl groups are attached to the nucleotides only after the RNA is transcribed from DNA. Since this process does not involve the nucleotide precursors directly, the methyl group will not be present in the nucleotide precursor found in the cell. Therefore, the answer to this question is No.

In both prokaryotes and eukaryotes, tRNAs and rRNAs are synthesized first as precursor molecules that are subsequently processed. The bases of pre-rRNAs are methylated for stability during this maturation process. This methylation adds a -CH3 group to some of the bases, which occurs after the precursor RNA is transcribed from the DNA.

Moreover, RNA molecules undergo further processing which can include base modification, splicing, and cleavage into functional units. However, these modifications including methylation happen after initial synthesis from the nucleotide precursors, which themselves do not contain methyl groups.