The excision (splicing) of many group I introns requires, in addition to the primary transcript RNA:
A) a cytosine nucleoside or nucleotide and a protein enzyme.
B) a guanine nucleoside or nucleotide (only).
C) a protein enzyme only.
D) a small nuclear RNA and a protein enzyme.
E) ATP, NAD, and a protein enzyme.

Question

Quizplus · Accepted Answer

Group I introns are a class of introns that are capable of self-splicing, which means they can remove themselves from RNA transcripts without the need for a protein enzyme. However, they require a guanine nucleoside or nucleotide to initiate the splicing process. This guanine acts as a cofactor, attacking the 5' splice site to start the transesterification reaction that leads to intron removal.

The Excision (Splicing) of Many Group I Introns Requires, in Addition