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  • 基因表达式的调制

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    Express Yourself
    ::表达自己

    This sketch illustrates some of the variability in human . The shape and other characteristics  that make each type of cell unique depend mainly on the specific   that particular cell type makes. Proteins are encoded in genes . All the cells in an organism have the same genes, so they all have genetic instructions for the same proteins. Obviously, different types of cells must use (or express) different genes to make different proteins.
    ::这个草图显示了人类的某些变异性。 使每一类细胞独一的形状和其他特征主要取决于特定细胞类型的具体特性。 蛋白质在基因中编码。 生物体中的所有细胞都有相同的基因,因此它们都有相同的蛋白质的基因指示。 显然,不同种类的细胞必须使用(或表达)不同的基因来制造不同的蛋白质。

    What Is Gene Expression?
    ::什么是 Gene 表达式 ?

    Using a gene to make a protein is called gene expression .  It includes the synthesis of the protein by the processes of of into mRNA, and of mRNA into a protein.  It may also include further processing of the protein after synthesis.
    ::使用基因来制造蛋白质称为基因表达方式,包括将蛋白质通过MRNA过程合成,并将MRNA合成为蛋白质,还可包括合成后进一步处理蛋白质。

    Gene expression is regulated to ensure that the correct proteins are made when and where they are needed. Regulation may occur at any point in the expression of a gene, from the start of the transcription phase of to the processing of a protein after synthesis occurs. The regulation of transcription is one of the most complicated parts of gene regulation in eukaryotic cells , and it is the focus of this concept.
    ::基因表达方式受监管,以确保正确的蛋白质在需要的时候和地点产生,在基因表达的任何时候,从合成后从转录阶段开始到处理蛋白质的阶段,都可能发生监管。 转录的监管是尿道细胞基因调节的最复杂部分之一,也是这一概念的重点。

    Regulation of Transcription
    ::追踪管制

    As shown in the figure , transcription is controlled by regulatory proteins . These proteins bind to regions of DNA, called regulatory elements , which are located near promoters . The promoter is the region of a gene where RNA polymerase binds to initiate transcription of the DNA to mRNA. After regulatory proteins bind to regulatory elements, the proteins can interact with RNA polymerase. Regulatory proteins are typically either activators or repressors.  Activators are regulatory proteins that promote transcription by enhancing the interaction of RNA polymerase with the promoter.  Repressors are regulatory proteins that prevent transcription by impeding the progress of RNA polymerase along the DNA strand, so the DNA cannot be transcribed to mRNA.
    ::如图所示,转录由管制性蛋白控制,这些蛋白质与DNA区域结合,称为管制性元素,在靠近促进者的地方。促进者是RNA聚合酶结合将DNA转录到 mRNA的基因区域。在管制性蛋白与管制性元素结合后,蛋白可以与RNA聚合酶相互作用。管制性蛋白通常是活化剂或抑制剂。活动者是通过加强RNA聚合酶与促进者的互动促进转录的管制性蛋白。抑制者是管制性蛋白,通过阻碍RNA聚合酶沿DNA链的进展来阻止转录,因此DNA不能被转录到mRNA。

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    Regulation of Transcription. Regulatory proteins bind to their corresponding regulatory elements in order to control transcription.
    ::监管监管:监管性蛋白质与其相应的监管要素捆绑在一起,以控制转录。

     

    Enhancers
    ::增强器

    Although regulatory proteins and elements are typically the key players in the regulation of transcription, other factors may also be involved. R egulation of transcription may also involve enhancers . Enhancers are distant regions of DNA that can loop back to interact with a gene's promoter. They can also  increase the likelihood that transcription of the gene will occur.
    ::虽然监管性蛋白质和元素通常是规范转录的关键角色,但也可能涉及其他因素,对转录的监管也可能涉及增强剂,增强者是遥远的DNA区域,可以回转与基因的促进者互动,还可以增加基因转录的可能性。

    The TATA Box
    ::TATATA 框框

    Different types of cells have unique patterns of regulatory elements that result in only the necessary genes being transcribed. That’s why a cell and nerve cell, for example, are so different from each other. Some regulatory elements, however, are common to virtually all genes, regardless of the cells in which they occur. An example is the TATA box , which is a regulatory element that is part of the promoter of almost every eukaryotic gene. A number of regulatory proteins bind to the TATA box, forming a multi-protein complex. It is only when all of the appropriate proteins are bound to the TATA box that RNA polymerase recognizes the complex and binds to the promoter so transcription can begin.
    ::不同种类的细胞具有独特的监管要素模式,这只导致必要的基因被转录。 举例来说,这就是为什么细胞和神经细胞彼此如此不同的原因。 然而,有些监管要素对几乎所有基因都是共同的,不管它们发生在哪个细胞中。 一个例子就是TATA框,它是一个监管要素,几乎是每个尿液基因的促进者的一部分。一些监管蛋白与TATA盒捆绑在一起,形成一个多蛋白复合体。只有当所有的合适的蛋白质都与TATA盒捆绑在一起时,RNA聚合酶才承认复杂和与促销者捆绑起来,从而可以开始转录。

    Regulation During Development
    ::制定期间的规章条例

    The regulation of gene expression is extremely important in  an organism's early . Regulatory proteins must "turn on" certain genes in particular cells at just the right time, so the individual develops normal organs and organ systems . Homeobox genes are important genes that regulate development. 
    ::对基因表达方式的规范在生物体早期就极为重要。 调节性蛋白必须“在适当的时候切换”某些基因,特别是细胞中的某些基因,这样个人就能发展正常的器官和器官系统。 软骨基因是调节发展的重要基因。

    Homeobox genes are a large group of similar genes that direct the formation of many body structures during the embryonic stage. In humans, there are an estimated 235 functional homeobox genes. They are present on every and generally grouped in clusters. Homeobox genes contain instructions for making chains of 60 amino acids , called homeodomains . Proteins containing homeodomains are that bind to and control the activities of other genes. The homeodomain is the part of the protein that binds to the target gene and controls its expression.
    ::Homeobox基因是导致在胚胎阶段形成许多身体结构的大量类似基因组。在人类中,估计有235种功能性软骨基因。它们存在于每个组群中,而且一般地分为各个组群。Homeobox基因含有60氨基酸链(称为Homeomomains)的指令。含有Homeomomains的蛋白质与其他基因的活动有联系和控制。Homeodomain是蛋白质的一部分,与目标基因联系在一起,控制其表达方式。

    Gene Expression and Cancer
    ::基因表达与癌症

    Some types of occur because of in the genes that control the . Cancer-causing mutations most often occur in two types of regulatory genes: proto-oncogenes and tumor-suppressor genes . Both are shown in the figure . 
    ::癌症致癌突变最经常发生在两类监管基因中:原致癌基因和肿瘤抑制基因。

    • Proto-oncogenes are genes that normally help cells divide. When a proto-oncogene mutates to become an oncogene , it is continuously expressed, even when it is not supposed to be. This is like a car's accelerator pedal being stuck at full throttle. The car keeps racing at top speed. A cell, in this case, keeps dividing out of control, which can lead to cancer.
      ::蛋白蛋白质是通常有助于细胞分裂的基因。 当原蛋白质变异成为蛋白质时, 它会持续表达, 即使它不应该存在。 这就像汽车的加速器脚踏板被完全卡在油门上。 汽车会以最高速度赛跑。 在这种情况下, 细胞会继续分裂, 从而导致癌症 。


      ::蛋白蛋白质是通常有助于细胞分裂的基因。 当原蛋白质变异成为蛋白质时, 它会持续表达, 即使它不应该存在。 这就像汽车的加速器脚踏板被完全卡在油门上。 汽车会以最高速度赛跑。 在这种情况下, 细胞会继续分裂, 从而导致癌症 。

    • Tumor suppressor genes are genes that normally slow down or stop . When a mutation occurs in a tumor suppressor gene, it can no longer control cell division. This is like a car without brakes. The car can't be slowed or stopped. A cell, in this case,  keeps dividing out of control, which can lead to cancer.
      ::肿瘤抑制基因是通常减慢或停止的基因。当肿瘤抑制基因发生突变时,它不再能够控制细胞分裂。这就像没有刹车的汽车。汽车不能减慢或停止。在这种情况下,细胞无法控制,这可能导致癌症。


      ::肿瘤抑制基因是通常减慢或停止的基因。当肿瘤抑制基因发生突变时,它不再能够控制细胞分裂。这就像没有刹车的汽车。汽车不能减慢或停止。在这种情况下,细胞无法控制,这可能导致癌症。

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    This flow chart shows how a series of mutations in tumor-suppressor genes and proto-oncogenes leads to cancer.
    ::本流程图显示肿瘤抑制基因和原致癌基因的一系列突变如何导致癌症。

     

    Summary
    ::摘要

    • Using a gene to make a protein is called gene expression. Gene expression is regulated to ensure that the correct proteins are made when and where they are needed. Regulation may occur at any stage of protein synthesis or processing.
      ::基因表达方式受管制,以确保正确的蛋白质在需要的时候和地点产生,在蛋白质合成或加工的任何阶段都可实行管制。
    • The regulation of transcription is controlled by regulatory proteins that bind to regions of DNA called regulatory elements, which are usually located near promoters. Most regulatory proteins are either activators that promote transcription, or repressors that impede transcription.
      ::转录管理由调控性蛋白控制,调控性蛋白与DNA区域(即调控性元素)相连,这些区域通常位于促销者附近,大多数调控性蛋白要么促进转录,要么阻碍转录的抑制剂。
    • A regulatory element common to almost all eukaryotic genes is the TATA box. A number of regulatory proteins must bind to the TATA box in the promoter before transcription can proceed.
      ::几乎所有电子基因的共同监管要素是TATA箱,许多监管蛋白质在转录之前必须与推广商的TATA箱捆绑,然后才能进行转录。
    • Regulation of gene expression is extremely important during an organism's early development. Homeobox genes — which encode for chains of amino acids called homeodomains — are important genes that regulate development.
      ::基因表达的调控在生物的早期发育中极为重要,Homeobox基因是调节发展的重要基因,它为氨基酸链编码,称为Homeomomains,是调节发展的重要基因。
    • Some types of cancer occur because of mutations in the genes that control the cell cycle. Cancer-causing mutations most often occur in two types of regulatory genes: tumor-suppressor genes and proto-oncogenes.
      ::某些类型的癌症是由于控制细胞循环的基因突变而发生的,致癌突变最经常发生在两类监管基因中:肿瘤抑制基因和原致癌基因。

    Review
    ::回顾

    1. Define gene expression.
    ::1. 界定基因表达方式。

    2. Why must gene expression be regulated?
    ::2. 为何必须对基因表达加以规范?

    3. Explain how regulatory proteins may activate or repress transcription.
    ::3. 解释管制性蛋白质如何激活或抑制转录。

    4. What is the TATA box, and how does it work?
    ::4. ATATA盒子是什么,如何运作?

    5. Describe homeobox genes and their role in  an organism's development.
    ::5. 描述原木箱基因及其在生物体发展中的作用。

    6. Discuss the role of regulatory gene mutations in cancer.
    ::6. 讨论管制基因突变在癌症中的作用。

    7. Explain the relationship between proto-oncogenes and oncogenes.
    ::7. 解释原致癌物与原致癌物之间的关系。

    8. If a newly fertilized egg contained a mutation in a homeobox gene, how do you think this would affect the developing embryo ? Explain your answer.
    ::8. 如果新受精的蛋含有原声箱基因的突变,你认为这会如何影响发育中的胚胎?解释你的答案。

    9. Which of the following are proteins?
    ::9. 以下哪些是蛋白质?

    a. repressors
    ::a. 压迫者

    b. promoters
    ::b. 推动者

    c. regulatory elements
    ::c. 监管要素

    d. all of the above  
    ::d. 以上所有情况

    10. Which of the following is a region of DNA?
    ::10. 下列哪些区域是DNA区域?

    a. homeodomain
    ::a. 内地

    b. activator
    ::b. 驱动器

    c. TATA box
    ::c. ATATA框

    d. both A and C  
    ::d. A 和 C 两者

    11. Compare and contrast enhancers and activators.
    ::11. 比较和对比增强者和推动者。

    12. True or False:  Mutations in genes that normally either promote or suppress cell division can both cause cancer.
    ::12. 真实或假基因:基因突变通常会促进或抑制细胞分裂,两者都会导致癌症。

    13. True or False:  Gene expression is only regulated at the transcriptional stage.
    ::13. 真实或假:基因表达方式只在转录阶段才受规范。

    14. True or False:  If RNA polymerase cannot bind to the promoter of a gene, it cannot transcribe that gene into mRNA.
    ::14. 真实或假:如果RNA聚合酶不能与基因的促销者捆绑,它就不能将该基因转录为mRNA。

    Explore More
    ::探索更多

    In order for controlled protein synthesis, genes must be regulated. Take a look here: 
    ::为了进行受控蛋白合成,必须管制基因。

     

     

    Mutations in the regulation of gene expression can lead to uncontrolled cell division, also known as cancer. Learn more here: 
    ::基因表达的调控中的变异可能导致不受控制的细胞分裂,也称为癌症。