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  • 蛋白质合成

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    The Art of Protein Synthesis
    ::蛋白质合成艺术

    This amazing artwork shows a process that takes place in the of all living things: the production of   . This process  is called , and it   actually consists of two processes — and translation. In eukaryotic cells , transcription takes place in the . During transcription, is used as a template to make a molecule of messenger RNA (mRNA). The molecule of mRNA then leaves the nucleus and goes to a in the cytoplasm , where translation occurs. During translation, the in mRNA is read and used to make a protein. These two processes are summed up by the central dogma of molecular biology : DNA → RNA → Protein . 
    ::这个惊人的艺术作品展示了在所有生物中发生的过程:生产。这个过程被称为。这个过程实际上由两个过程组成——和翻译。在eukarycoy细胞中,转录在转录中进行。在转录过程中,作为模板,用来制造送信者RNA(mRNA)的分子。MRNA的分子然后离开核,然后转到一个进行翻译的细胞托盘中。在翻译过程中,读取并使用 mRNA来制造蛋白质。这两个过程由分子生物学的中央教条加以总结:DNA RNA Protein。

    Transcription
    ::翻译

    Transcription is the first part of the central dogma of molecular biology: DNA → . It is the transfer of genetic instructions in DNA to mRNA. During transcription, a strand of mRNA is made to complement  a strand of DNA. You can see how this happens in the diagram .
    ::Transnation是分子生物学核心教条的第一部分:DNA = 。这是DNA中的遗传指示转移到 mRNA 。在转录过程中,将一组 mRNA 做成一组 mRNA 来补充DNA 。您可以看到图表中是如何发生的 。

    lesson content
    Overview of Transcription. Transcription uses the sequence of bases in a strand of DNA to make a complementary strand of mRNA. Triplets are groups of three successive nucleotide bases in DNA. Codons are complementary groups of bases in mRNA.

     

    Steps of Transcription
    ::定时步骤

    Transcription takes place in three steps: initiation , elongation , and termination . The steps are illustrated in the figure .
    ::追踪分三个步骤进行:启动、延长和终止。这些步骤在图中说明。

    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 ready to make a strand of mRNA with a complementary sequence of bases.
      ::启动是转录的开始。 当 RNA 聚合酶与一个叫促进者的基因区域结合时, 就会发生这种情况。 这表明DNA会松开, 这样酶就可以“ 读” DNA线之一的底部。 酶可以做一串 mRNA , 并配有一系列补充的基数序列 。
    2. Elongation is the addition of nucleotides to the mRNA strand.
      ::延长是指在 mRNA 线上添加核糖核酸。
    3. Termination is the ending of transcription. The mRNA strand is complete, and it detaches from DNA.
      ::终止是转录的结束。 mRNA 线是完整的, 从DNA中分离出来 。
    lesson content
    Steps of Transcription. Transcription occurs in three steps: initiation, elongation, and termination.

     

    Processing mRNA
    ::处理 mRNA

    In eukaryotes , the new mRNA is not yet ready for translation. At this stage, it is called pre-mRNA, and it must go through more processing before it leaves the nucleus as mature mRNA. The processing 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。 在现阶段, 它被称为 pret- mRNA , 在它离开核作为成熟的 mRNA 之前, 它必须经过更多的处理。 处理可能包括拼写、 编辑和多词拼写。 这些过程以不同方式修改 mRNA 。 这些修改允许使用单一基因制造一个以上的蛋白质 。

    • Splicing removes introns from mRNA, as shown in the diagram . Introns are regions that do not code for the protein. The remaining mRNA consists only of regions called exons that do code for the protein. The ribonucleoproteins in the diagram are small proteins in the nucleus that contain RNA and are needed for the splicing process.
      ::如图所示,相切从 mRNA 中移除了数子。 数子是不对蛋白质进行编码的区域。 其余的 mRNA 仅包括被称为对蛋白质进行编码的Exons 区域。 图表中的核核核核蛋白蛋白是含有 RNA 的微小蛋白, 并且是串联过程所需要的。
    • Editing changes some of the nucleotides in mRNA. For example, a 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 an earlier stop signal in mRNA.
      ::编辑在 mRNA 中更改了某些核糖核酸。 例如, 名为 APOB 的人类蛋白质, 有助于在 mRNA 中运输, 其因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 中添加了早期停止信号 。
    • 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, and it protects mRNA from enzymes that might break it down.
      ::MRNA 中添加了“尾部 ” 。 尾部由 As 串组成( 9个底座 ) 。 它标志着 mRNA 的末端 。 它也参与从核输出 mRNA , 保护 mRNA 不受可能破裂的酶的伤害 。
    lesson content
    Splicing. Splicing removes introns from mRNA.

    Translation
    ::笔译 笔译

    Translation is the second part of the central dogma of molecular biology: RNA → Protein . It is the process in which the genetic code in mRNA is read to make a protein. Translation is illustrated in the diagram . After mRNA leaves the nucleus, it moves to a ribosome, which consists of rRNA and proteins. The ribosome reads the sequence of codons in mRNA, and molecules of tRNA bring amino acids to the ribosome in the correct sequence.
    ::翻译是分子生物学核心教条的第二部分:RNA Protein。 这是读取 mRNA 中的遗传代码以产生蛋白质的过程。 翻译在图表中说明 。 在 mRNA 离开核后, 它会移动到血清中, 由 RRNA 和蛋白组成。 血清中读取 mRNA 中的codons 序列, TRNA 的分子会将氨基酸以正确的顺序带入血清中 。

    To understand the role of tRNA, you need to know more about its structure. Each tRNA molecule has an anticodon for the amino acid it carries. An anticodon is complementary to the codon for an amino acid. For example, the amino acid lysine has the codon AAG, so the anticodon is UUC. Therefore, lysine would be carried by a tRNA molecule with the anticodon UUC. Wherever the codon AAG appears in mRNA, a UUC anticodon of tRNA temporarily binds. While bound to mRNA, tRNA gives up its amino acid. With the help of rRNA, bonds form between the amino acids as they are brought one by one to the ribosome, creating a polypeptide chain. The chain of amino acids keeps growing until a stop codon is reached.
    ::要了解 tRNA 的作用, 您需要了解它的结构。 每个 tRNA 分子都有对应氨基酸的抗codon。 抗codon 是对氨基酸的codon的补充。 例如, 氨基酸碱有codon AAG, 所以抗codon 是UUC。 因此, 碱性将用抗codon UUC 的tRNA 分子携带。 无论Codon AAG 在 mRNA 中出现, 一种UUC TRNA 的抗codon 暂时粘合。 虽然它与 mRNA 捆绑在一起, TRNA 却放弃其氨基酸 。 在 RNA 的帮助下, 氨基酸之间的粘合形式, 当它们被一个一个一个带到树脂中, 形成一个聚苯二酸链。 氨基酸链会持续增长, 直到达到 停止 codon 。

    lesson content
    Translation. Translation of the codons in mRNA to a chain of amino acids occurs at a ribosome. Find the different types of RNA in the diagram. What are their roles in translation?

     

    What Happens Next?
    ::接下来会发生什么?

    After a polypeptide chain is synthesized, it may undergo additional processes. For example, it may assume a folded shape due to interactions between  its amino acids. It may also bind with other polypeptides or with different types of molecules, such as lipids or . Many proteins travel to the within the cytoplasm to be modified for the specific job they will do.
    ::在合成了聚石化物链之后,它可能会经历额外的过程。例如,它可能因其氨基酸之间的相互作用而形成折叠形状。它也可能与其他聚石化物或不同种类的分子(如脂类或脂类)捆绑在一起。许多蛋白质会去细胞顶层内部,以便根据它们将从事的具体工作加以修改。

    Summary
    ::摘要

    • Protein synthesis is the process in which cells make proteins. It occurs in two stages: transcription and translation.
      ::蛋白质合成是细胞制造蛋白质的过程,分两个阶段进行:转录和翻译。
    • Transcription is the transfer of genetic instructions in DNA to mRNA in the nucleus. It includes three steps: initiation, elongation, and termination. After the mRNA is processed, it carries the instructions to a ribosome in the cytoplasm.
      ::Transnation 是指将DNA中的遗传指示转移到核中的 mRNA 。 它包括三个步骤: 启动、 延长和终止。 在 mRNA 处理后, 它将指示传送到细胞托盘中的血清 。
    • Translation occurs at the ribosome, which consists of rRNA and proteins. In translation, the instructions in mRNA are read, and tRNA brings the correct sequence of amino acids to the ribosome. Then, rRNA helps bonds form between the amino acids, producing a polypeptide chain.
      ::由 RRNA 和 蛋白质组成 的 REBOSM 进行 翻译。 翻译时读取 mRNA 的指令, TRNA 将氨基酸的正确序列带到 REBOSM 。 然后, RRNA 帮助氨基酸 之间形成债券, 产生聚石化链 。
    • After a polypeptide chain is synthesized, it may undergo additional processing to form the finished protein.
      ::在合成了聚石化物链之后,它可能经过额外的加工,以形成成品蛋白质。

    Review
    ::回顾

    1. Relate protein synthesis and its two major phases to the central dogma of molecular biology.
    ::1. 将蛋白质合成及其两个主要阶段与分子生物学核心教条联系起来。

    2. Identify the steps of transcription, and summarize what happens during each step.
    ::2. 确定抄录步骤,并概述每个步骤发生的情况。

    3. Explain how mRNA is processed before it leaves the nucleus.
    ::3. 解释MRNA离开核心之前是如何处理的。

    4. Describe what happens during the translation phase of protein synthesis.
    ::4. 描述蛋白质合成翻译阶段发生的情况。

    5. What additional processes might  a polypeptide chain undergo after it is synthesized?
    ::5. 在合成了聚多石化链之后,该链还可能经历哪些其他过程?

    6. Where does transcription take place in eukaryotes?
    ::6. 欧卡利奥特语的笔录在哪里进行?

    7. Where does translation take place?
    ::7. 翻译在何处进行?

    8. Which type of RNA (mRNA, rRNA, or tRNA) best fits each of the statements below? Choose only one type for each.
    ::8. 哪种RNA(mRNA、RRNA或tRNA)最适合以下每种语句?选择一种。

    a. contains the codons
    ::a. 含有共融

    b. contains the anticodons
    ::b. 含有抗codon

    c. makes up the ribosome, along with proteins
    ::c. 与蛋白质一起构成脊髓炎

     

    9. If the DNA has a triplet code of CAG in one strand (the strand used as a template for transcription)...
    ::9. 如果DNA有三重CAG编码(用作转录模板的线)......。

    a. What is the complementary sequence on the other DNA strand?
    ::a. 其他DNA线上的互补序列是什么?

    b. What is the complementary sequence in the mRNA? What is this sequence called?
    ::b. MRNA中的互补序列是什么?这个序列叫什么?

    c. What is the resulting sequence in the tRNA? What is this sequence called? What do you notice about this sequence compared to the original DNA triplet on the template strand?
    ::c. TRNA 中产生的结果序列是什么?这个序列叫什么?与模板线上的原DNA三联体相比,你注意到这个序列是什么?

     

    10. The promoter is a region located in the:
    ::10. 推动者是位于以下区域的一个区域:

    a. DNA
    ::a. DNA

    b. mRNA
    ::b. mRNA

    c. tRNA
    ::c. TRNA

    d. both A and B
    ::d. A 和 B 两者

     

    11. True or False:  Introns in mRNA bind to tRNA at the ribosome.
    ::11. 真实或假的:在乳房腐烂时,MRNA中的电离子与tRNA捆绑在一起。

    12. True or False:  tRNAs can be thought of as the link between amino acids and codons in the mRNA.
    ::12. 真实或假:tRNAs可被视为氨基酸与氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基氨基甲酸酯之间的联系。

    Explore More  
    ::探索更多

    Messenger RNA molecules are "spliced" in order to create the mRNA involved in protein synthesis. Learn the process here:
    ::为了创建涉及蛋白质合成的 mRNA 。 在此学习此过程 :