分子生物学名词解释

1、.Isoaccepting tRNA：同工受体tRNA，能解读同工密码子的不同tRNA。inducer;（诱导物）凡能诱导操纵子开启的效应物称为诱导物。Insulater（绝缘子）： 真核生物基因组的调控元件之一，亦为一种边界元件。Promoter（启动子）：指DNA分子上被RNApol调节因子等识别并结合形成转录起始复合体的区域，是控制转录起始的序列。Gene（基因）：书 Enhancer (增强子)：是一个顺式作用序列，能够提高一些真核生物启动子的利用，并能够在启动子任何方向以及任何位置(上游或者下游)作用。Gene /ciston (基因/顺反子)：指能产生一条多肽链的DNA片段。包括编

2、码区和其上下游区域(引导区和尾)，以及在编码片段间(外显子)的割裂序列(内含子)。Gene family (基因家族)：一系列外显子相关联的基因，其成员是由一个祖先基因复制或趋异产生Induction (诱导)：指细菌或者酵母只有当底物存在时才会合成某种酶的能力。当用在基因表达中，指诱导物与调控蛋白结合造成的转录转换。Initiation factors (起始因子，原核中IF，真核中eIF)：在蛋白质合成起始阶段特异性作用于核糖体小亚基的蛋白质。Intron(内含子)：一段DNA片段，它转录但通过将其两端的序列(外显子)剪接在一起而被移出转录本。Isoaccepting tRNAs (同工t

3、RNA)：携带相同的氨基酸的tRNA。Molecular chaperone (分子伴侣)：协助一些蛋白质装配或者恰当折叠所需的蛋白质，但这种蛋白质并不是靶复合物的成分。Operator(操纵基因)：DNA 上的一个位点，阻遏蛋白能与之结合抑制相邻启动子从而抑制转录。Primosome (引发体)：指在非连续DNA复制中，每个岗崎片段合成引发反应中涉及的蛋白质复合体。引发体能沿着DNA 移动，参与连续的引发反应。Promoter (启动子)：结合RNA 聚合酶并起始转录的DNA 区域-10 sequence (-10区)：位于细菌基因起始位点上游10bp的一段保守序列TATAATG。在RNA聚

4、合酶诱导DNA 溶解起始时起作用。-35 sequence (-35区)：细菌基因起始位点上游35bp处的保守序列，在RNA聚合酶起始识别中作用。Pseudogenes (假基因)：由原始活性基因突变引起的基因组中稳定但不活泼的成分。Pseudogenes are segments of DNA that are related to real genes. Pseudogenes have lost at least some functionality, relative to the complete gene, in cellular gene expression or protei

5、n-coding ability.snRNPs：核小核糖体蛋白质(snRNA 与蛋白质结合)颗粒。negative regulation (负调节):当细胞中存在的调节蛋白处于激活状态时,会使目的基因的表达 活性受到抑制,我们称这种抑制基因表达活性的调节类型为负调节。顺式作用元件(cis-acting element)存在于基因旁侧序列中能影响基因表达的序列。顺式作用元件包括启动子、增强子、调控序列和可诱导元件等，它们的作用是参与基因表达的调控。顺式作用元件本身不编码任何蛋白质，仅仅提供一个作用位点，要与反式作用因子相互作用而起作用。Cis-Acting Element Download PD

6、F (6,857 KB)The Cis-acting element must be located in the same DNA strand as its target to act upon it during transcription. Genes that are conserved across species will also display conservation at the level of their transcriptional regulation and this will be reflected in the organization of cis-e

7、lements mediating this regulation. Using a computational approach, clusters of transcription factor binding sites that are absolutely conserved in order and in spacing across human, rat, and mouse genomes were identified.mutation hot spot(突变热点):突变机率较高的碱基序列。trans-acting element反式作用因子：是指能直接或间接地识别或结合在各

8、类顺式作用元件核心序列上参与调控靶基因转录效率的蛋白质。多为转录因子。大多数真核转录调节因子由某一基因表达后，可通过另一基因的特异的顺式作用元件相互作用，从而激活另一基因的转录。这种调节蛋白称反式作用因子。转录因子: 真核基因的转录调节蛋白又称转录调节因子或转录因子。Transcription factorIn molecular biology, a transcription factor (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of gen

9、etic information from DNA to messenger RNA, by binding to a specific DNA sequence.12 In turn, this helps to regulate the expression of genes near that sequence. This is essential in embryogenesis.Transcription factors work alone or with other proteins in a complex, by promoting (as an activator), or

10、 blocking (as a repressor) the recruitment of RNA polymerase (the enzyme that performs the transcription of genetic information from DNA to RNA) to specific genes.345A defining feature of transcription factors is that they contain at least one DNA-binding domain (DBD), which attaches to a specific s

11、equence of DNA adjacent to the genes that they regulate.67 Transcription factors are usually classified into different families based on their DBDs.89 Other proteins such as coactivators, chromatin remodelers, histone acetyltransferases, histone deacetylases, kinases, and methylases, while also esse

12、ntial to gene regulation, lack DNA-binding domains, and, therefore, are not transcription factors.10终止密码子：在mPNA翻译过程中，起蛋白质合成终止信号作用的密码子，即UAA， UAG和UGAmulti gene family（多基因家族）是指由某一祖先基因经过重复和变异所产生的一组基因。A methyltransferase is a type of transferase enzyme that transfers a methyl group from a donor to an acc

13、eptor.Methylation often occurs on nucleic bases in DNA or amino acids in protein structures. Methytransferases use a reactive methyl group bound to sulfur in S-adenosyl methionine (SAM) as the methyl donor.DNA methylation is often utilized to silence and regulate genes without changing the original

14、DNA sequence, an example of epigenetic modification. This methylation occurs on cytosine residues. DNA methylation may be necessary for normal growth from embryonic stages in mammals. When mutant embryonic stem cells lacking the murine DNA methyltransferase gene were introduced to a germline of mice

15、, they caused a recessive lethal phenotype.1 Methylation may also be linked to cancer development, as methylation of tumor suppressor genes promotes tumorgenesis and metastasis.2Site-specific methyltransferases have the same DNA target sequences as certain restriction enzymes. Methylation can also s

16、erve to protect DNA from enzymatic cleavage, since restriction enzymes are unable to bind and recognize externally modified sequences. This is especially useful in bacterial restriction modification systems that use restriction enzymes to cleave foreign DNA while keeping their own DNA protected by m

17、ethylation.Methylation of amino acids in the formation of proteins leads to more diversity of possible amino acids and, therefore, more diversity of function. The methylation reaction occurs on nitrogen atoms either on the N terminus or on the side-chain position of the protein and are usually irrev

18、ersible.翻译起始因子：翻译起始所必需的特异蛋白因子。与核糖体、信使核糖核酸、起始转移核糖核酸等组成动态翻译起始复合体。真核和原核生物翻译起始因子分别有eIF 16和IF 13等。Initiation factors起始因子（英语：）是指翻译起始阶段端结合到核糖体小亚基上的一些蛋白质，翻译是蛋白质生物合成中的一部分。house-keeping genes持家基因()：又称管家基因，是指所有细胞中均要稳定表达的一类基因，其产物是对维持细胞基本生命活动所必需的。如微管蛋白基因、糖酵解酶系基因与核糖体蛋白基因等。HSP：英文全称为：heat shock protein，中文名为：热休克蛋白，属

19、于应激反应性蛋白，高温应激可诱导该蛋白质形成。HSP是分子伴侣的一种，在蛋白质翻译后修饰过程中，起到促进需要折叠的多肽链折叠为天然空间构象的蛋白质。genetic mapping遗传作图（）是指应用遗传学技术构建能显示基因以及其他序列特征在基因组上位置的图。遗传学技术包括杂交育种实验，对人类则是检查家族史或系谱。与任何一种图一样，一个遗传图必须显示出显著特征的位置，在地理图中，标记是图中可以识别的部分，如河流、道路以及建筑物。Gene mapping describes the methods used to identify the locus of a gene and the dista

20、nces between genes.Genome，基因组，一个细胞或者生物体所携带的一套完整的单倍体序列，包括全套基因和间隔序列。operon操纵子（）：指启动基因、操纵基因和一系列紧密连锁的结构基因的总称。转录的功能单位。很多功能上相关的基因前后相连成串，由一个共同的控制区进行转录的控制，包括结构基因以及调节基因的整个DNA序列。主要见于原核生物的转录调控，如乳糖操纵子、阿拉伯糖操纵子、组氨酸操纵子、色氨酸操纵子等gene expression基因表达()是指细胞在生命过程中，把储存在DNA顺序中遗传信息经过转录和翻译，转变成具有生物活性的蛋白质分子。Gene expression is

21、the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as transfer RNA (tRNA) or small nuclear RNA (snRNA) genes, the product is a functional RNA.效应物_百度百科 是指能引起生理效应的物质。In biochemistry

22、, an effector molecule is usually a small molecule that selectively binds to a protein and regulates its biological activity. In this manner, effector molecules act as ligands that can increase or decrease enzyme activity, gene expression, or cell signalling. Effector molecules can also directly reg

23、ulate the activity of some mRNA molecules (riboswitches).In some cases, proteins can be considered to function as effector molecules, especially in cellular signal transduction cascades.The term effector is used in other fields of biology. For instance, the effector end of a neuron is the terminus w

24、here an axon makes contact with the muscle or organ that it stimulates or suppresses.跳跃基因或转座子:一段可以从原位上单独复制或断裂下来，环化后插入另一位点，并对其后的基因起调控作用的DNA序列。Denaturation (biochemistry)Denaturation is a process in which proteins or nucleic acids lose the quaternary structure, tertiary structure and secondary structu

25、re which is present in their native state, by application of some external stress or compound such as a strong acid or base, a concentrated inorganic salt, an organic solvent (e.g., alcohol or chloroform), radiation or heat.3 If proteins in a living cell are denatured, this results in disruption of

26、cell activity and possibly cell death. Protein denaturation is also a consequence of cell death.45 Denatured proteins can exhibit a wide range of characteristics, from conformational change and loss of solubility to aggregation due to the exposure of hydrophobic groups.乳糖操纵子：大肠杆菌中与乳糖代谢功能相关的基因成镞的串联在一

27、起共同组成一个转录单位即乳糖操纵子，包括：Z 、Y 及A三个结构基因，一个操纵序列O ,一个启动序列P及一个调节基因I。 增强子：增强子是能够结合特异基因调节蛋白，促进邻近或远处特定基因表达的DNA序列。增强子距转录起始点的距离变化很大，但总是作用于最近的启动子。前导序列：存在于原核生物，为编码区之前的不翻译的mRNA区段，是mRNA区段类型。在原核生物中，一条mRNA分子常常编码数种不同的多肽链。这种多顺反子mRNA的头一条多肽链合成的起点，同RNA分子的5P末端间的距离可达数百个核苷酸，这段编码区之前的不翻译的mRNA区段，叫做前导序列。Klenow片段：又名DNA聚合酶I（DNA pol

28、 1）大片段（克列诺片段，Klenow fragment，或称克列诺酶，Klenow enzyme）：E.coli DNA聚合酶经胰蛋白酶或枯草杆菌蛋白酶部分水解生成的C末端605个氨基酸残基片段。该片段保留了DNA聚合酶I的5-3聚合酶和3-5外切酶活性，但缺少完整酶的5-3外切酶活性。DNA聚合酶 I（DNA-pol I）断开后的存在另一个323个氨基酸残基片段，保留5-3外切酶活性。terminator终止子(T)是给予RNA聚合酶转录终止信号的DNA序列。在一个操纵元中至少在构基因群最后一个基因的后面有一个终止子。In genetics, a transcription termina

29、tor is a section of nucleic acid sequence that marks the end of a gene or operon in genomic DNA during transcription. This sequence mediates transcriptional termination by providing signals in the newly synthesized mRNA that trigger processes which release the mRNA from the transcriptional complex.

30、These processes include the direct interaction of the mRNA secondary structure with the complex and/or the indirect activities of recruited termination factors. Release of the transcriptional complex frees RNA polymerase and related transcriptional machinery to begin transcription of new mRNAs.作为起始信

31、号的密码子称为起始密码子。silencer沉默子（）也称为沉默子元件，是真核基因中的一种特殊的序列，与增强子有许多类似之处。按功能特性，真核基因顺式作用元件可以分为启动子，增强子和沉默子。沉默子能够同反式因子结合从而阻断增强子及反式激活因子的作用，并最终抑制该基因的转录活性。弱化子attenuator，是指原核生物的操纵子中可以明显衰减乃至终止转录作用的一段核苷酸序列，位于操纵子的上游。An insulator is a genetic boundary element that blocks the interaction between enhancers and promoters.It

32、 is thought that an insulator must reside between the enhancer and promoter to inhibit their subsequent interactions. Insulators therefore determine the set of genes an enhancer can influence. The need for insulators arises where two adjacent genes on a chromosome have very different transcription p

33、atterns; it is critical that the inducing or repressing mechanisms of one do not interfere with the neighbouring gene.1 Insulators have also been found to cluster at the boundaries of topologically associating domains (TADs) and may have a role in partitioning the genome into chromosome neighborhood

34、s - genomic regions within which regulation occurs.23Insulator activity is thought to occur primarily through the 3D structure of DNA mediated by proteins including CTCF.4 Insulated neighborhoods formed by physical interaction between two CTCF-bound DNA loci contain the interactions between enhancer

35、s and their target genes.5 顺式作用元件.遗传学：一种长约数百个核苷酸对,通常位于启动子正调控元件或负调控元件之间的一种调控序列.primosome引发体（）是DNA复制过程中的一种负责专一性引发的多酶复合物，位于复制叉的前端，能够生成后随链冈崎片段合成必需的RNA引物，主要成分为引物酶（如DnaG）以及DNA解旋酶（如DnaB）等。editosome编辑体；英文名称：；定义1：进行RNA转录物编辑的一个复杂系统。除了有许多酶之外，还有一个指导RNA。spliceosome剪接体（英文：）是指进行RNA剪接时形成的多组分复合物，其大小为60S，主要是由小分子的核RNA

36、和蛋白质组成。A spliceosome is a large and complex molecular machine found primarily within the splicing speckles of the cell nucleus of eukaryotic cells. The spliceosome is assembled from snRNAs and protein complexes. The spliceosome removes introns from a transcribed pre-mRNA, a type of primary transcrip

37、t. This process is generally referred to as splicing.1 Only eukaryotes have spliceosomes and some organisms have a second spliceosome, the minor spliceosome.2 An analogy is a film editor, who selectively cuts out irrelevant or incorrect material (equivalent to the introns) from the dailies and sends

38、 the cleaned-up version to be screened for the producer.HTH；最早在原核基因的激活蛋白和阻遏蛋白中发现的调控蛋白, 是一种同型二聚体。In proteins, the helix-turn-helix (HTH) is a major structural motif capable of binding DNA. It is composed of two helices joined by a short strand of amino acids and is found in many proteins that regulat

39、e gene expression. It should not be confused with the helix-loop-helix domain.1 basic helix-loop-helix DNA-binding domainBasic helix-loop-helix structural motif ofARNT. Two-helices(blue) are connected by a shortloop(red).1Stringent response严紧反应：当细菌在缺乏合成蛋白质所必须的氨基酸时，停止合成核糖体RNA的反应。From Wikipedia, the f

40、ree encyclopediaThe stringent response, also called stringent control, is a stress response of bacteria and plant chloroplasts in reaction to amino-acid starvation,1 fatty acid limitation,2 iron limitation,3 heat shock4 and other stress conditions. The stringent response is signaled by the alarmone

41、(p)ppGpp, and modulates transcription of up to 1/3 of all genes in the cell. This in turn causes the cell to divert resources away from growth and division and toward amino acid synthesis in order to promote survival until nutrient conditions improve.In Escherichia coli, (p)ppGpp production is media

42、ted by the ribosomal protein L11 (rplK resp. relC) and the ribosome-associated (p)ppGpp synthetase I, RelA; deacylated tRNA bound in the ribosomal A-site is the primary induction signal.1 RelA converts GTP and ATP into pppGpp by adding the pyrophosphate from ATP onto the 3 carbon of the ribose in GT

43、P, releasing AMP. pppGpp is converted to ppGpp by the gpp gene product, releasing Pi. ppGpp is converted to GDP by the spoT gene product, releasing pyrophosphate (PPi). GDP is converted to GTP by the ndk gene product. Nucleoside triphosphate (NTP) provides the Pi, and is converted to Nucleoside diph

44、osphate (NDP).In other bacteria, the stringent response is mediated by a variety of RelA/SpoT Homologue (RSH) proteins,5 with some having only synthetic, or hydrolytic or both (Rel) activities.6During the stringent response, (p)ppGpp accumulation affects the resource-consuming cell processes replica

45、tion, transcription, and translation. (p)ppGpp is thought to bind RNA polymerase and alter the transcriptional profile, decreasing the synthesis of translational machinery (such as rRNA and tRNA), and increasing the transcription of biosynthetic genes.7 Additionally, the initiation of new rounds of

46、replication is inhibited and the cell cycle arrests until nutrient conditions improve.8 Translational GTPases involved in protein biosynthesis are also affected by ppGpp, with Initiation Factor 2 (IF2) being the main target.9Chemical reaction catalyzed by RelA:ATP + GTP AMP + pppGppChemical reaction

47、 catalyzed by SpoT:ppGpp GDP + PPi or pppGpp - GTP + PPiExtensive Mendeley collection of scientific papers covering stringent response is available here.Molecular biologyMolecular biology /mlkjlr/ concerns the molecular basis of biological activity between biomolecules in the various systems of a ce

48、ll, including the interactions between DNA, RNA, and proteins and their biosynthesis, as well as the regulation of these interactions.1 Writing in Nature in 1961, William Astbury described molecular biology as:.not so much a technique as an approach, an approach from the viewpoint of the so-called b

49、asic sciences with the leading idea of searching below the large-scale manifestations of classical biology for the corresponding molecular plan. It is concerned particularly with the forms of biological molecules and . is predominantly three-dimensional and structuralwhich does not mean, however, th

50、at it is merely a refinement of morphology. It must at the same time inquire into genesis and function.2Life is a characteristic distinguishing physical entities having biological processes, such as signaling and self-sustaining processes, from those that do not, either because such functions have c

51、eased, or because they never had such functions and are classified as inanimate. Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. The criteria can at times be ambiguous and may or may not define viruses, viroids, or potential artificial life as living. Bi

52、ology is the primary science concerned with the study of life, although many other sciences are involved.The definition of life is controversial. The current definition is that organisms maintain homeostasis, are composed of cells, undergo metabolism, can grow, adapt to their environment, respond to

53、 stimuli, and reproduce. However, many other biological definitions have been proposed, and there are some borderline cases of life, such as viruses. Throughout history, there have been many attempts to define what is meant by life and many theories on the properties and emergence of living things,

54、such as materialism, the belief that everything is made out of matter and that life is merely a complex form of it; hylomorphism, the belief that all things are a combination of matter and form, and the form of a living thing is its soul; spontaneous generation, the belief that life repeatedly emerg

55、es from non-life; and vitalism, a now largely discredited hypothesis that living organisms possess a life force or vital spark. Modern definitions are more complex, with input from a diversity of scientific disciplines. Biophysicists have proposed many definitions based on chemical systems; there ar

56、e also some living systems theories, such as the Gaia hypothesis, the idea that the Earth itself is alive. Another theory is that life is the property of ecological systems, and yet another is elaborated in complex systems biology, a branch or subfield of mathematical biology. Abiogenesis describes

57、the natural process of life arising from non-living matter, such as simple organic compounds. Properties common to all organisms include the need for certain core chemical elements to sustain biochemical functions.Life on Earth first appeared as early as 4.28 billion years ago, soon after ocean form

58、ation 4.41 billion years ago, and not long after the formation of the Earth 4.54 billion years ago.1234 Earths current life may have descended from an RNA world, although RNA-based life may not have been the first. The mechanism by which life began on Earth is unknown, though many hypotheses have been formulated and are often based on the MillerUrey experiment. The earliest known life forms are microfossils of bacteria. In July 2016, scientists reported identifying a set of 355 genes believed to be present in the last universal common ancestor (LUC