Biochemistry 2280A Lecture Notes - Central Dogma Of Molecular Biology, Endonuclease, Adenine
12 Dec 2012
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Formation of mrnas: rna processing in eucaryotic cells. Primary transcript becomes a mrna for export out of the nucleus and translation. Three main steps: 5" capping, 3" polyadenylation, splicing. When rna is made, first nucleotide added is a triphosphate, and a 7-methylguanosine is added to it to the 5" end through a unique 5"-5" linkage. Marks the 5" end of the mrna as being intact. Required for mrna export from the nucleus. Required for translation of the mrna into protein (translational initiation) Sequence that signals polyadenylation, endonuclease cleavage and addition of polya tail. Helps protect the 3" end of the mrna from degradation. Indicates that the 3" end of the mrna is intact and therefore is important for: export out of the nucleus, translation. In eucaryotic cells, protein encoding sequences are interrupted by one or more noncoding sequences called introns. The splicing pattern is often tissue specific. Introns are spliced out of the primary transcript to give the mature rna.
