Section outline

  • General

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  • 翻译

    What you will learn
    ::你会学到什么

    • What is transcription
      ::什么是转录
    • Steps in the process of transcription
      ::笔录过程中的步骤
    • How is transcribed mRNA processed in eukaryotes
      ::如何用 eukaryotes 处理转录的 mRNA ?

    A hand writing notes about DNA transcription with DNA and RNA structures shown.

    How does a cell use the information in its DNA?
    ::细胞如何使用DNA中的信息?

    To transcribe means ‘‘to paraphrase or summarize in writing’’. The information in is transcribed - or summarized - into a smaller version - - that can be used by the . This process is called transcription.
    ::将信息转录为可被转录(或归纳为较小版本)的文本,供用户使用。此过程称为转录。

    Transcription
    ::翻译

    The process in which cells make is called . It actually consists of two processes: transcription and . Transcription takes place in the of the eukaryotic cells . It uses DNA as a template to make an RNA molecule. RNA then leaves the nucleus and goes to a in the cytoplasm , where translation occurs. Translation reads the in mRNA and makes a protein.
    ::细胞制造的过程。 它实际上由两个过程组成: 转录 和 。 转录 在 eukaryatic 单元格中发生 。 它使用 DNA 作为模板来制造 RNA 分子 。 RNA 然后离开 核, 转到 cytoplasm 中进行翻译 。 翻译读取 mRNA 中的 mRNA 并制作蛋白质 。

    Transcription is the first part of the central dogma of molecular biology : DNA → RNA . It is the transfer of genetic instructions in DNA to messenger RNA (mRNA). During transcription, a strand of mRNA is made that is complementary to a strand of DNA.
    ::转基因是分子生物学核心教条的第一部分:DNA RNA, DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA DNA

    How is DNA transcribed into RNA?
    ::DNA是如何被转录到RNA的?

    Steps of Transcription
    ::定时步骤

    Transcription takes place in three steps: initiation , elongation , and termination . The steps are illustrated in the  Figure below.
    ::追踪分三个步骤进行:启动、延长和终止。下图说明了这些步骤。

    1. Initiation is the beginning of transcription. It occurs when the RNA polymerase binds to a region of a gene called the promoter . This signals the DNA to unwind so the enzyme can ‘‘read’’ the bases in one of the DNA strands. The enzyme is now ready to make a strand of mRNA with a complementary sequence of bases.
      ::启动是转录的开始。 当 RNA 聚合酶连接到一个叫做促进者的基因区域时, 就会发生这种情况。 这表示DNA会松开, 这样酶可以读取DNA线之一的底部。 酶现在可以做成一组 mRNA , 并配有一系列基数的互补序列 。
    2. Elongation is the addition of nucleotides to the mRNA strand. RNA polymerase reads the unwound DNA strand and builds the mRNA molecule, using complementary base pairs . There is a brief time during this process when the newly formed RNA is bound to the unwound DNA. During this process, adenine (A) in the DNA binds to uracil (U) in the RNA.
      ::RNA聚合酶读取无声DNA链,并使用互补基底配对构建 mRNA分子。在此过程中,当新形成的RNA与无声DNA捆绑在一起时,有短暂的时间。在这一过程中,DNA中的(A)与RNA中的uracil(U)结合。
    3. Termination is the ending of transcription and occurs when RNA polymerase crosses a stop (termination) sequence in the gene. The mRNA strand is complete, and it detaches from DNA.
      ::终止是转录的结束,当 RNA 聚合酶在基因中跨过停止(终止)序列时发生。 mRNA 线是完整的, 从DNA中分离出来 。
    Steps of Transcription. Transcription occurs in the three steps - initiation, elongation, and termination - shown here.

    Processing mRNA
    ::处理 mRNA

    In eukaryotes, the new mRNA is not yet ready for translation. It must go through additional processing before it leaves the nucleus. This may include splicing , editing , and polyadenylation . These processes modify the mRNA in various ways. Such modifications allow a single gene to be used to make more than one protein.
    ::在 eukaryotes 中, 新的 mRNA 尚未准备好翻译。 它在离开核之前必须经过额外的处理 。 这可能包括拼写、 编辑和多词性。 这些过程以不同的方式修改 mRNA 。 这样修改可以让一个单一的基因用于制造一个以上的蛋白质 。

    • Splicing removes introns from mRNA (see the  Figure ). Introns are regions that do not code for proteins. The remaining mRNA consists only of regions that do code for proteins, which are called exons . Ribonucleoproteins are nucleoproteins that contain RNA. Small nuclear ribonucleoproteins are involved in pre-mRNA splicing.
      ::相切从 mRNA 中去除电离子体(见图 ) 。 电离子体是不对蛋白质进行编码的区域。 其余的 mRNA 仅包括对蛋白质进行编码的区域, 这些区域被称为exons 。 Ribonunucleoproteins 是含有 RNA 的核蛋白质。 小型核子核子核子核子蛋白质参与了 mRNA 之前的复制。
    • Editing changes some of the nucleotides in mRNA. For example, the human protein called APOB, which helps transport in the , has two different forms because of editing. One form is smaller than the other because editing adds a premature stop signal in the mRNA.
      ::修改 mRNA 中的某些核糖核酸。 例如, 被称为APOB 的人类蛋白质, 有助于迁移, 因为编辑而有两种不同的形式。 一种形式小于另一种形式, 因为编辑在 mRNA 中增加了一个过早停止信号 。
    • Polyadenylation adds a “tail” to the mRNA. The tail consists of a string of As (adenine bases). It signals the end of mRNA. It is also involved in exporting mRNA from the nucleus. In addition, the tail protects mRNA from enzymes that might break it down.
      ::尾部由一串As(9个基底)组成。它标志着 mRNA的结束。它也参与从核输出 mRNA 。此外,尾部保护 mRNA 不受可能破裂的酶的影响。
    The splicing of pre-mRNA, showing introns and exons in mRNA processing.
    Splicing. Splicing removes introns from mRNA. UTR is an untranslated region of the mRNA.

     

     

     

     

    Summary
    ::摘要

    • Transcription is the DNA → RNA part of the central dogma of molecular biology.
      ::DNADNARNA是分子生物学核心教条的一部分。
    • Transcription occurs in the nucleus of eukaryotic cells.
      ::解密发生于 eukaryaty 单元格核心 。
    • During transcription, a copy of mRNA is made that is complementary to a strand of DNA. In eukaryotes, mRNA may be modified before it leaves the nucleus of eukaryotic cells.
      .
      ::在转录过程中,将制作一份 mRNA 副本,作为DNA链条的补充。在eukaryotes中, mRNA 可以在离开 eukaryotes 细胞核心之前修改 。

    Review
    ::回顾

    1. What is protein synthesis?
      ::什么是蛋白质合成?
    2. What enzyme is involved in transcription?
      ::转录中涉及什么酶?
    3. Describe transcription.
      ::描述转录。
    4. Describe splicing. Distinguish introns from exons.
      ::描述插件。 区分Exions 和 exons 的 introns 。
    5. How may mRNA be modified before it leaves the nucleus?
      ::如何在MRNA离开核之前修改它?