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单选题 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
学科：Biochemistry 《生物化学》一 专业基础课（全英教学）
时间：2024-06-22 03:53:04
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题目1单选题
Transcription is catalyzed by ___________________________________, which use ribonucleoside 5′-triphosphates to synthesize RNA complementary to the template strand of DNAA. DNA-dependent DNA polymerasesB. DNA-dependent RNA polymerasesC. RNA-dependent RNA polymerasesD. RNA-dependent DNA polymerases
题目2单选题
_______ 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 planetA. DNAB. RNAC. ProteinD. Sugar
题目3单选题
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 RNAA. 103 to 104B. 104 to 105C. 105 to 106D. 106 to 107
题目4单选题
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 DNAA. 2B. 3C. 4D. 5
题目5单选题
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 complexA. TFIIAB. TFIIBC. TFIIED. TFIIH
题目6单选题
In eukaryotes, most introns undergo splicing by the same lariat-forming mechanism as the ________ intronsA. group IB. group IIC. group IIID. group IV
题目7单选题
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 ancestorsA. group IB. group IIC. group IIID. group IV
题目8单选题
Bacteriophage T4 has several protein-coding genes with ______ introns. Introns may be more common in archaea than in bacteriaA. group IB. group IIC. group IIID. group IV
题目9单选题
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 requirementsA. 1B. 2C. 3D. 5
题目10单选题
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 snRNAsA. 7B. 8C. 9D. 10
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