[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fpajO5qWJUx4Oya-9X1V_5Hudh0fQfAVChTllVY1o7ss":3},{"answer":4,"createTime":5,"id":6,"options":7,"origin":12,"question":19,"related":20,"source":31,"type":104},[],"2024-06-22 11:53:05",154255773,[8,9,10,11],"The pathway consists of two major parts, binding and initiation, each with multiple steps. First, the polymerase, directed by its bound σ factor, binds to the promoter. A closed complex (in which the bound DNA is intact) and an open complex (in which the bound DNA is intact but partially unwound near the −10 sequence) form in succession","Second, transcription is initiated within the complex, leading to a conformational change that converts the complex to the elongation form, followed by movement of the transcription complex away from the promoter (promoter clearance)","Any of these steps can be affected by the specific makeup of the promoter sequences. The σ subunit dissociates stochastically (at random) as the polymerase enters the elongation phase of transcription. The protein NusA (Mr 54,430) binds to the elongating RNA polymerase, competitively with the σ subunit","Once transcription is complete, NusA dissociates from the enzyme, the RNA polymerase dissociates from the DNA, and a σ factor (σ70 or another) can again bind to the enzyme to initiate transcription",{"count":13,"courseId":14,"courseImg":15,"courseName":16,"workId":17,"workName":18},63,"ecb63186fd2348dd972900f765a15722","https:\u002F\u002Ftihai-oss-cloud.itihey.com\u002Fimg\u002Fe91b8b9d3b83a0d6a9d655b826214095.jpg","Biochemistry 《生物化学》一 专业基础课（全英教学）","ae15e9a34f574f36a08f7007eb9f27e2","Test 26 - Lecture 26","What are the pathway of transcription initiation and the fate of the σ subunit in bacteria",[21,33,42,51,61,70,79,84,89,95],{"answer":22,"createTime":23,"id":24,"options":25,"question":30,"source":31,"type":32},[],"2024-06-22 11:53:03",154255746,[26,27,28,29],"DNA-dependent DNA polymerases","DNA-dependent RNA polymerases","RNA-dependent RNA polymerases","RNA-dependent DNA polymerases","Transcription is catalyzed by ___________________________________, which use ribonucleoside 5′-triphosphates to synthesize RNA complementary to the template strand of DNA","v1",0,{"answer":34,"createTime":23,"id":35,"options":36,"question":41,"source":31,"type":32},[],154255747,[37,38,39,40],"DNA","RNA","Protein","Sugar","_______ is the only macromolecule known to have a role both in the storage and transmission of information and in catalysis, which has led to much speculation about its possible role as an essential chemical intermediate in the development of life on this planet",{"answer":43,"createTime":23,"id":44,"options":45,"question":50,"source":31,"type":32},[],154255748,[46,47,48,49],"103 to 104","104 to 105","105 to 106","106 to 107","RNA polymerases lack a separate proofreading 3′ → 5′ exonuclease active site (such as that of many DNA polymerases), and the error rate for transcription is higher than that for chromosomal DNA replication—approximately one error for every _________ ribonucleotides incorporated into RNA",{"answer":52,"createTime":53,"id":54,"options":55,"question":60,"source":31,"type":32},[],"2024-06-22 11:53:04",154255749,[56,57,58,59],"2","3","4","5","The DNA-dependent RNA polymerase of E. coli is a large, complex enzyme with ___ core subunits (α2ββ′ω; Mr 390,000) and a sixth subunit, one of a group designated σ, with variants designated by size (molecular weight). The σ subunit binds transiently to the core and directs the enzyme to specific binding sites on the DNA",{"answer":62,"createTime":53,"id":63,"options":64,"question":69,"source":31,"type":32},[],154255750,[65,66,67,68],"TFIIA","TFIIB","TFIIE","TFIIH","In eukaryotes, not only does _______ participate in formation of the closed complex during assembly of a transcription complex, but some of its subunits are also essential components of the separate nucleotide-excision repair complex",{"answer":71,"createTime":53,"id":72,"options":73,"question":78,"source":31,"type":32},[],154255751,[74,75,76,77],"group I","group II","group III","group IV","In eukaryotes, most introns undergo splicing by the same lariat-forming mechanism as the ________ introns",{"answer":80,"createTime":53,"id":81,"options":82,"question":83,"source":31,"type":32},[],154255752,[74,75,76,77],"The spliceosomes used in nuclear RNA splicing almost certainly evolved from more ancient ________ introns, with the snRNPs contributing much greater levels of catalytic flexibility and regulation relative to their selfsplicing ancestors",{"answer":85,"createTime":53,"id":86,"options":87,"question":88,"source":31,"type":32},[],154255753,[74,75,76,77],"Bacteriophage T4 has several protein-coding genes with ______ introns. Introns may be more common in archaea than in bacteria",{"answer":90,"createTime":53,"id":91,"options":92,"question":94,"source":31,"type":32},[],154255754,[93,56,57,59],"1","The average half-life of the mRNAs of a vertebrate cell is about ___ hours, with the pool of each type of mRNA turning over about 10 times per cell generation. The half-life of bacterial mRNAs is much shorter—only about 1.5 min—perhaps because of regulatory requirements",{"answer":96,"createTime":53,"id":97,"options":98,"question":103,"source":31,"type":32},[],154255755,[99,100,101,102],"7","8","9","10","There are at least ___ structural classes of ribozymes that engage in self-cleavage; all use general acid and base catalysis to promote the attack of a 2′-hydroxyl group on an adjacent phosphodiester bond. The splicing reaction that occurs in a spliceosome relies on a catalytic center formed by the U2, U5, and U6 snRNAs",1]