利用差热分析(DTA)及变温红外光谱技术测定了季戊四醇-氨基异丁基三醇(PETAM)二元体系的相图。研究表明,在该相图中存在两个低共熔点和一个转晶点,多元醇分子在低温时的有序和高温时的无序是影响二元体系不同相间互溶度的重要因素

利用固体与分子经验电子理论,对奥氏体中含合金元素γ-Fe晶胞的价电子结构进行了计算分析.结果表明,合金元素溶入γ-Fe晶胞后,其价电子结构发生了较大变化,Fe原子杂化态向较高杂阶迁移,其相结构因子均有不同程度的增加.同时晶胞内形成了由强键组成的八面体结构,阻碍了原子的移动,使得γ-Fe晶胞在相变过程中产生\类拖曳效应\,提高过冷奥氏体的稳定性,亦会延缓马氏体相变的进程

采用分子动力学和EAM(embeddedatommethod)势,模拟研究了热脉冲对金属铜从晶态到非晶态转变的影响.计算结果表明,热脉冲作用下,转变时体系平均温度高于平衡计算熔点,结构转变是过热熔化过程,系统不可能发生从晶态到非晶态非平衡转变.随着热脉冲频率的增大,转变所需热脉冲幅度减小,体系转变过热度降低

用一种新的擦伤电极装置来研究化学镀Ni-P合金在3.5%NaCl溶液中的再钝化行为。结果表明,Ni-P合金的再钝化动力学服从i(t)=A1exp(-C1t)+A2exp(-C2t)方程。在低电位区,Ni迅速氧化,并在表面形成稳定的氧化物NiOOH。氧化膜的生长服从高场离子传导机制;在高电位区,吸附过程迅速发生,界面上的单分子吸附膜使裸体表面电流很快衰减,吸附的H2PO2-有效地阻止了Ni位上的溶解

◼ What are the main challenges of translation and how do organisms overcome them? ◼ What is the organization of nucleotide sequence information in mRNA? ◼ What is the structure of tRNAs, and how do aminoacyl tRNA synthetases recognize and attach the correct amino acids to each tRNA? ◼ How does the ribosome orchestrate the translation process?

TOPIC 1 Principles of Transcriptional Regulation [watch the animation] TOPIC 2 Regulation of Transcription Initiation: Examples from Bacteria (Lac operon, alternative s factors, NtrC,MerR, Gal rep, araBAD operon) TOPIC 3 Examples of Gene Regulation after Transcription Initiation (Trp operon) TOPIC 4 The Case of Phage λ: Layers of Regulation

Similarity of regulation between eukaryotes and prokaryote 1.Principles are the same: • signals (信号), • activators and repressors (激活蛋白和阻 遏蛋白) • recruitment and allostery, cooperative binding (招募，异构和协同结合) 2. The gene expression steps subjected to regulation are similar, and the initiation of transcription is the most pervasively regulated step

Most of the eukaryotic genes are mosaic (嵌合体), consisting of intervening sequences separating the coding sequence ◼ Exons (外显子): the coding sequences ◼ Introns (内含子) : the intervening sequences ◼ RNA splicing: the process by which introns are removed from the pre￾mRNA. ◼ Alternative splicing (可变剪接): some pre-mRNAs can be spliced in more than one way , generating alternative mRNAs. 60% of the human genes are spliced in this manner

1. Please define the term “mutation”, and list the major types of DNA mutations and their corresponding phenotypic effects. (20 points) 2. Please define the term “DNA lesion”. Please list the three types of DNA lesions and the chemical or physical mutagens cause these lesions. (20 points)

Q1. Prokaryotic cell E. coli consists of a single closed-circular DNA molecule of 4.6 x 106 bp long. This DNA molecule would be 1.6 mm if the double helix is relaxed. Please describe what strategies does E. coli use to pack such a long molecules into its nucleoid less than a micrometer (mm) in diameter. (20 points)