Biochemistry 2280A Lecture Notes - Lecture 19: Polyadenylation, Guanosine, Intron

• School: Western University
• Department: Biochemistry
• Course: Biochemistry 2280A
• Professor: Derek Mc Lachlin

Document Summary

Triphosphate replaced by 7 methyl guanosine placed on mrna (cid:1007)" pol(cid:455)ade(cid:374)(cid:455)latio(cid:374) Almost all eukaryotic mrnas end with a long ~300 base polya tail. Sequence recruits cleavage protein complex adds polya tail. I(cid:373)po(cid:396)ta(cid:374)(cid:272)e of the 5"cap a(cid:374)d (cid:1007)"pol(cid:455)a tail (cid:1005). Ma(cid:396)k the 5" a(cid:374)d (cid:1007)" e(cid:374)ds of the (cid:373)rna as (cid:271)ei(cid:374)g i(cid:374)ta(cid:272)t required form mrna export and translation: protect the mrna from degradation. Protein encoding sequences (exons) are interrupted by noncoding sequences (introns) Introns are spliced out of the primary transcript to give the mature mrna. Human factor 8 gene mostly non coding, very little exons. Splicing increases the coding capacity of the genome. An rna can be spliced in different ways to create related but distinct proteins. The splicing pattern is often different in different tissues. Splicing requires specific sequence elements in the rna (cid:1005). 5" spli(cid:272)e ju(cid:374)(cid:272)tio(cid:374) (cid:1006). (cid:1007)" spli(cid:272)e ju(cid:374)(cid:272)tio(cid:374: branch point you always get agg at junction you can tell where the intron was from it.