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  • General

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  • 蛋白质

    What you will learn
    ::你会学到什么

    • What are proteins
      ::什么是蛋白质
    • Levels of protein structure
      ::蛋白质结构水平
    • Important functions of proteins
      ::蛋白质的重要功能

    Various protein sources including chicken, eggs, soy milk, and kidney beans on plates.

    You may have been told proteins are good for you. Do these look good to you?
    ::你可能被告知蛋白质对你有好处 这些看起来好看吗?

    Proteins as food . To you, these may not look appetizing (or they might), but they do provide a nice supply of amino acids , the monomers of proteins. Proteins have many important roles, from transporting, signaling, receiving, and catalyzing to storing, defending, and allowing for movement . Where do you get the amino acids needed so your can make their own proteins? If you cannot make it, you must eat it.
    ::蛋白质作为食物。 对于你来说,这些看起来可能不尽如人意(或可能),但它们确实提供了大量氨基酸,即蛋白质的单体。 蛋白质有许多重要作用,从运输、信号、接收、催化到储存、防御和允许移动。你从哪得到所需的氨基酸,以便自己制造蛋白质?如果你不能制造,你就必须吃。

    Proteins
    ::蛋白质

    A protein is an made up of small molecules called amino acids , the monomers of proteins. There are 20 different amino acids commonly found in the proteins of living organisms . Small proteins may contain just a few hundred amino acids, whereas large proteins may contain thousands of amino acids. The largest known proteins are titins, found in muscle and composed of over 27,000 amino acids.
    ::蛋白质是由小分子组成的,称为氨基酸,蛋白质的单体体。在活生物体的蛋白质中,通常有20种不同的氨基酸。小蛋白质可能只含有几百种氨基酸,而大蛋白质可能含有数千种氨基酸。最大的已知蛋白质是乳头,存在于肌肉中,由27 000多种氨基酸组成。

    The Figure  shows the general structure of all amino acids. Only the side chain, R, varies from one amino acid to another. In the amino acid glycine, for example, the side chain is simply hydrogen (H). In glutamic acid, in contrast, the side chain is CH2CH2COOH. Variable side chains give amino acids different chemical properties. The order and properties of amino acids determine the shape of the protein. The shape of the protein determines the function of the protein.
    ::图中显示了所有氨基酸的总体结构。只有侧链,即R,各处的氨基酸不同。例如,在氨基酸甘油中,侧链只是氢(H),而在谷颈酸中,侧链是CH2CH2COOH。可变侧链赋予氨基酸不同的化学特性。氨基酸的顺序和特性决定蛋白质的形状。蛋白质的形状决定蛋白质的功能。

    General structure of amino acids with labeled groups and variable side chain.
    General Structure of Amino Acids. KEY: White = hydrogen (H), Blue = nitrogen (N), Dark Grey = carbon (C), Red = oxygen (O), R = variable side chain
    DID YOU KNOW?
    Although there are hundreds of amino acids found in nature, only 20 amino acids are encoded by the standard in humans and other living organisms. Selenocysteine and pyrrolysine are two other amino acids that scientists discovered can be involved in , making them the 21st and 22nd amino acids possibly present in proteins.
     

    Protein Structure
    ::蛋白结构

    When amino acids bind together, they may form short chains of two or just a few amino acids. These short chains are called peptides . When amino acids form long chains, the chains are called polypeptides . A protein consists of one or more polypeptide chains. A protein may have up to four levels of structure. The lowest level, a protein’s primary structure, is its sequence of amino acids. Higher levels of protein structure are described in the animation below. The complex structures of different proteins give them unique properties, which they need to carry out their various jobs in living organisms. 
    ::当氨基酸结合在一起时,它们可能形成两个或几个氨基酸的短链。这些短链被称为peptides。当氨基酸形成长链时,链被称为聚虫。一个蛋白质由一个或一个以上的聚虫化链组成。一个蛋白质可能具有四个层次的结构。一个蛋白质的主要结构,是其氨基酸的序列。下面的动画中描述的是更高层次的蛋白结构。不同的蛋白质的复杂结构给他们提供了独特的特性,他们需要在生物生物中从事各种工作。

    Functions of Proteins
    ::蛋白质函数

    Proteins play many important roles in living things. Some proteins help cells keep their shape (structural proteins), some, such as connective and motor proteins, make up muscle tissues , and some transport items in and out of cells (transport proteins). Some proteins act as signals, and other proteins receive those signals. are proteins that speed up chemical reactions in cells. Other proteins are antibodies , which bind to foreign substances such as and target them for destruction. Still other proteins carry messages or transport materials. For example, human red blood cells contain a protein called hemoglobin , which binds with oxygen. Hemoglobin allows the to carry oxygen from the lungs to cells throughout the body. Proteins have many vital roles in living things, from transporting, signaling, receiving, and catalyzing to storing, defending, and allowing movement.
    ::蛋白质在生物中起着许多重要作用。有些蛋白质帮助细胞保持形状(结构性蛋白 ) , 有些如连接和运动蛋白质,组成肌肉组织,有些是细胞内外的运输物品(运输蛋白质 ) 。有些蛋白质作为信号,而其他蛋白质则接收这些信号。有些蛋白质是加速细胞化学反应的蛋白质。其他蛋白质是抗体,它们与外国物质(例如,并针对这些物质进行破坏 ) 。还有一些蛋白质携带信息或运输材料。例如,人类红血细胞含有一种叫做血红蛋白的蛋白,它与氧结合。血红蛋白允许将氧从肺中携带氧到整个身体的细胞中。 蛋白质在生命中,从运输、信号、接收和催化到储存、维护和允许移动等许多关键作用。

    Proteins and Diet
    ::蛋白质和饮食

    Proteins in the diet are necessary for life. Dietary proteins are broken down into their component amino acids when food is digested. Cells can then use the components to build new proteins. Humans are able to synthesize all but nine of the twenty common amino acids. The nine amino acids, called essential amino acids , must be consumed in foods.
    ::饮食中的蛋白质是生命所必需的。饮食中的蛋白质在食物消化时被分解成其成分的氨基酸。 细胞然后可以使用成分来制造新的蛋白质。 人类可以合成20种常见氨基酸中除9种外的所有物质。 九种氨基酸,即所谓的基本氨基酸,必须用在食物中。

    CAN YOU MATCH?

    Try matching the levels of protein structure with their description.
    ::尝试将蛋白质结构的级别与其描述匹配 。

     

    Science Friday: The Medical Wonders of Worm Spit
    ::科学星期五:虫虫病的医学奇迹

    How useful is worm spit? It turns out that worm spit, also known as silk, is a very useful material in medicine. In this video by Science Friday , Dr. David Kaplan describes how silk is used in a variety of medical applications.
    ::蠕虫唾液有多么有用? 事实证明,蠕虫唾液(又称丝绸)是医学上非常有用的材料。 在科学周五的这段影片中,大卫·卡普兰博士讲述了丝绸在各种医疗应用中是如何使用的。

    Summary
    ::摘要

    • Proteins are organic compounds made up of amino acids, the monomers of proteins.
      ::蛋白质是由氨基酸组成的有机化合物,蛋白质的单体。
    • A protein may have up to four levels of structure. The complex structures of different proteins give them unique properties.
      ::一种蛋白质可能具有四个层次的结构,不同的蛋白质的复杂结构赋予它们独特的特性。
    • Enzymes are proteins that speed up biochemical reactions in cells. Antibodies are proteins that target pathogens for destruction.
      ::酶是加速细胞中生化反应的蛋白质,抗体是针对病原体进行破坏的蛋白质。

    Review
    ::回顾

    1. Proteins are made out of ____________.
      ::蛋白质是用... 做的
    2. What determines the primary structure of a protein?
      ::是什么决定了蛋白质的主要结构?
    3. State two functions of proteins.
      ::蛋白质的两种状态功能。
    4. What are enzymes?
      ::什么是酶?
    5. Describe the role of hemoglobin.
      ::描述血红蛋白的作用。