分子试题07.docVIP

课程编号 北京理工大学2009-2010学年第2学期 2007级分子生物学期末试题A卷 班级 学号 姓名 成绩 Part 1. Basic Concepts (20 points, 2 points each) 1.Promoter RNA聚合酶同启动子结合的区域称为启动子区。将各种原核基因同RNA聚合酶全酶结合后，用DNase I水解DNA，最后得到与RAN聚合酶结合而未被水解的DNA片段，这些片段有一个由5个核苷酸(TATAA)组成的共同序列，以其发现者的名字命名为Pribnow框(Pribnowbox)，这个框的中央位于起点上游10bp处，所以又称—10序列(—10 sequence)，后来在—35 bp处又找到另一个共同序列(TTGACA)。Hogness等在真核基因中又发现了类似Pribnow框的共同序列，即位于—25～—30 bp处的TATAAAAG，也称TATA框(TATAbox)。TATA框上游的保守序列称为上游启动子元件(upstream promoter element，UPE)或上游激活序列(uptreamactivatingsequence，UAS)。另外在—70～—78 bp处还有一段共同序列CCAAT，称为CAAT框(CAAT box) 2.Z-DNA Z-DNA又称Z型DNA，是DNA双螺旋结构的一种形式，具有左旋型态的双股螺旋（与常见的B-DNA相反），并呈现锯齿形状。Z-DNA为三种具生物活性的DNA双螺旋结构之一。 3.Toprim Domain The toprim (topoisomerase-primase) domain is a conserved region from DnaG primases, topoisomerases, OLD family nucleases and RecR/M DNA repair proteins. The fold of the TOPRIM domain resembles a Rossman-like nucleotide binding fold, with a central beta-sheet formed by 4 parallel beta-strands flanked by 3 alpha-helices. Only 5 residues are conserved across all TOPRIM domain, 2 of these are glycines which may play a structural role, the other 3 are acidic residues that are present in 2 conserved sequence motifs. These may have a metal binding function The TOPRIM domain may form a shallow groove on these molecules and play a role in the binding of double-helical DNA/RNA hybrids. 4.Pre-mRNA Precursor mRNA (pre-mRNA) is an immature single strand of messenger ribonucleic acid (mRNA). pre-mRNA is synthesized from a DNA template in the cell nucleus by transcription. pre-mRNA comprises the bulk of heterogeneous nuclear RNA (hnRNA). The term hnRNA is often used as a synonym for pre-mRNA, although strictly speaking hnRNA may include nuclear RNA transcripts that do not end up as cytoplasmic mRNA. Once pre-mRNA has been completely processed, it is termed mature messenger RNA, mature mRNA, or simply mRNA. 5.V(D)J Rearrangements V(D)J Rearrangements /reco