BIO$2110$–$Genetics$ $ $ $ $ $ Name$_________________________________$Recitation$2$–$Transcription$$ $ $ $$Group$Members$________________________$ ________________________$$ ________________________$$$$The$C-terminal$domain$(CTD)$of$the$large$subunit$of$eukaryotic$RNA$polymerase$II$(pol$II)$contains$several$repeats$of$the$amino$acid$sequence$YSPTSPS.$$Phosphorylation$of$serine-5$(S5)$is$involved$in$the$transition$from$transcription$initiation$to$elongation$and$in$the$capping$of$nascent$pol$II$transcripts.$$The$phosphorylation$of$serine-2$(S2)$is$involved$in$splicing$and$polyadenylation.$$$$Y$=$tyrosine$ S$=$serine$ P$=$proline$ T$=$threonine$$1.$ Which,$if$any,$CTD$serines$are$phosphylated$$$on$pol$II$that$is$not$bound$to$DNA?$$on$pol$II$during$transcription$initiation?$$on$pol$II$during$transcription$elongation?$$on$pol$II$during$transcription$termination?$$$$$2.$ What$enzyme$phosphorylates$pol$II$during$transcription$initiation?$$Why$doesn’t$this$enzyme$phosphorylate$pol$II$during$elongation$or$termination?$$$$$$$$$3.$ S5$phosphorylation$is$involved$with$two$activities$during$transcription.$$What$are$they?$$How$does$S5$phosphorylation$facilitate$these$a ctivities?$$$$$$$ $$$4.$ S2$phosphorylation$is$involved$with$two$activities$during$transcription.$$What$are$they?$$How$does$S2$phosphorylation$facilitate$these$a ctivities?$$How$is$it$possible$for$S2$phosphorylation$to$facilitate$both$of$these$activities$(i.e.$why$aren’t$these$activities$mutually$exclusive)?$$$$$$$$$$$5.$ Polyadenylation$of$pol$II$transcripts$is$functionally$associated$with$pol$II$transcription$termination.$$Explain$this$functional$relationship.$$$$$$$$$$6.$ What$structure$protects$the$5’$ends$of$eukaryotic$mRNAs$from$degradation$by$5’$exonucleases?$$$What$features$of$this$structure$are$unique$(or$unusual)?$$Feel$free$to$draw$this$structure$as$part$of$your$exp l anation.$$$$$$$$$$$7.$
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