#Question id: 18748
#Unit 13. Methods in Biology
#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: 5645
#Unit 5. Developmental Biology
A reproductive difference between sea urchins and humans is ________.
#Question id: 7083
#Unit 5. Developmental Biology
During development in avian embryo, the sheet of cells that grows anteriorly from Koller’s sickle combines with the primary hypoblast to form the complete hypoblast layer, also called the:
#Question id: 6962
#Unit 5. Developmental Biology
In which way is the organizer region of the sea urchin similar to that in frogs?