#Question id: 4508
#Unit 3. Fundamental Processes
Statement: In the case of group II introns, the chemistry of splicing and the RNA intermediates produced are the same as those for nuclear pre-mRNA.
Explanations: I. The intron uses an A residue within the branch site to attack the phosphodiester bond at the boundary between its 5’ end and the end of the 5’ exon-that is, at the 5’ splice site. This reaction produces the branched lariat.
II. A second reaction in which the newly freed 3’ -OH of the exon attacks the 3’splice site, releasing the intron as a lariat and fusing the 3’ and 5’ exons.
#Question id: 4509
#Unit 3. Fundamental Processes
Which group of introns contain an “internal guide sequence”
#Question id: 4510
#Unit 3. Fundamental Processes
Which statements are true about group I and group II introns,
A. Group I (and II) introns are not enzymes because they have a turnover number of only 1.
B. A third transesterification reaction can occur to cyclize the intron.
C. They cannot be readily converted into ribozymes.
D. It is similar to the way that the self-cleaving Hammerhead could be converted to a ribozyme by separating the active site from the substrate
#Question id: 4511
#Unit 3. Fundamental Processes
The proteins are not needed for the splicing reaction itself, because
#Question id: 4512
#Unit 3. Fundamental Processes
Some pre-mRNAs can be spliced in more than one way. Thus, mRNAs containing different selections of exons can be generated from a given pre-mRNA, called
#Question id: 4513
#Unit 3. Fundamental Processes
Different snRNPs recognize the same (or overlapping) sequences in the pre-mRNA at different stages of the splicing reaction, which two snRNPs recognizing the 5’ splice site