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  • 活物中的化学反应

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    Assembly Line
    ::平线

    We stay alive because millions of different chemical reactions are taking place inside our bodies all the time. Each of our is like the busy auto assembly line pictured here. Raw materials, half-finished products, and waste materials are constantly being used, produced, transported, and excreted. The "workers" on the cellular assembly line are mainly enzymes. These are the that make happen.
    ::因为我们的身体里不断发生着数以百万计的不同化学反应。 我们每个人都像这里所描绘的繁忙的汽车组装线一样。原材料、半成品和废物不断被使用、生产、运输和排泄。 细胞组装线上的“工人”主要是酶。这些就是产生这些结果的原因。

    What Are Biochemical Reactions?
    ::什么是生化反应?

    Chemical reactions that take place inside living things are called biochemical reactions.  The sum of all the biochemical reactions in an organism is called  metabolism . Metabolism includes both exothermic (energy-releasing) chemical reactions and endothermic (energy-absorbing) chemical reactions.
    ::生物体中发生的化学反应被称为生化反应。生物体中所有生物化学反应的总和被称为新陈代谢。代谢包括异温(能源释放)化学反应和异温(能源吸收)化学反应。

    Catabolic Reactions
    ::代谢反应

    Exothermic reactions in organisms are called catabolic reactions . These reactions break down molecules into smaller units and release energy . An example of a catabolic reaction is the breakdown of glucose during , which releases energy that cells need to carry out life processes.
    ::生物体中的异热反应被称为代谢反应。这些反应将分子分解成小单位并释放能量。 代谢反应的一个例子是在细胞进行生命过程时释放出能量的葡萄糖分解。

    Anabolic Reactions
    ::新旧反应

    Endothermic reactions in organisms are called  anabolic reactions . These reactions build up bigger molecules from smaller ones and absorb energy. An example of an anabolic reaction is the joining of amino acids to form a protein. Which type of reactions — catabolic or anabolic — do you think occur when your body digests food ?
    ::有机体中的异变反应被称为新陈代谢反应,这些反应从较小的分子中积累出更大的分子并吸收能量。代谢反应的一个例子是氨基酸结合形成蛋白质。你认为哪种反应 — — 代谢反应或新陈代谢反应 — — 是在身体消化食物时发生的?

    Enzymes
    ::酶

    Most of the biochemical reactions that happen inside of living organisms require  help. Why is this the case? For one thing, temperatures inside living things are usually too low for biochemical reactions to occur quickly enough to maintain life. The concentrations of reactants may also be too low for them to come together and react. Where do the biochemical reactions get the help they need to proceed? From the enzymes. 
    ::活生物体内部发生的大多数生化反应都需要帮助。 为什么这样呢? 首先,活生物体中的温度通常太低,无法迅速发生生化反应以维持生命。反应器的浓度可能也太低,无法联合起来作出反应。生化反应在哪里得到它们需要的帮助?从酶中得到的帮助。

    An is a protein that speeds up a biochemical reaction. It is a biological catalyst . An enzyme generally works by reducing the amount of activation energy needed to start the reaction. The graph shows the activation energy needed for glucose to combine with oxygen. Less activation energy is needed when the correct enzyme is present than when it is not present.
    ::一种可以加速生物化学反应的蛋白质。这是一种生物催化剂。一种酶通常通过减少启动反应所需的活化能量来发挥作用。图表显示了葡萄糖与氧结合所需的活化能量。在正确的酶存在时,需要的活化能量比不存在时少。

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    Enzyme Action. This graph shows what happens when glucose combines with oxygen. An enzyme speeds up the reaction by lowering the activation energy. Compare the activation energy needed with and without the enzyme.
    ::酶作用。 此图显示当葡萄糖与氧结合时会发生什么。 酶会通过降低激活能量来加速反应。 比较所需的活化能量, 不论是否带有酶 。

    How Well Enzymes Work
    ::如何使用良好的酶

    Enzymes are involved in most biochemical reactions, and they do their jobs extremely well. A typical biochemical reaction that would take several days or even several centuries to happen  without an enzyme is likely to occur in just a split second with the proper enzyme! Without enzymes to speed up biochemical reactions, most organisms could not survive.
    ::大多数生化反应都涉及到酶,它们的工作非常出色。 典型的生化反应需要数天甚至几百年的时间,而没有酶就发生。 仅仅一瞬间,就有可能与适当的酶发生。 没有酶来加速生化反应,大多数生物就无法存活下来。

    Enzymes are substrate-specific. The  substrate  of an enzyme is the specific substance it affects. Each enzyme works only with a particular substrate, which explains why there are so many different enzymes. In addition, for an enzyme to work, it requires specific conditions, such as the right temperature and pH. Some enzymes work best under acidic conditions, for example, while others work best in neutral environments.
    ::酶是特定基质的。 酶的基质是它所受影响的特定物质。 每一种酶只使用特定的基质, 这解释了为什么有这么多不同的酶。 此外, 一种酶要工作, 需要特定的条件, 比如正确的温度和pH值。 有些酶在酸性条件下最有效, 而另一些则在中性环境中最有效。

    Enzyme-Deficiency Disorders
    ::酶-缺能疾病

    There are hundreds of known inherited metabolic disorders in humans. In most of them, a single enzyme is either not produced by the body at all, or is otherwise produced in a form that doesn't work. The missing or defective enzyme is like an absentee worker on the cell's assembly line. T oxic chemicals build up, or an essential product isn't made. Generally, the normal enzyme is missing because the individual with the disorder inherited two copies of a gene , which may have originated many generations previously .
    ::人类有数百种已知的遗传代谢紊乱。 在大部分人中,单一酶不是完全由身体产生,或是以不起作用的形式产生。 缺少的或有缺陷的酶就像细胞组装线上的缺勤工人一样。 有毒化学物质积聚起来,或者没有制造基本产品。 一般来说,正常的酶失踪了,因为患有这种紊乱的人继承了两个基因的复制本,而这个基因可能是几代人以前产生的。

    Any given inherited metabolic disorder is generally quite rare in the general . However, there are so many different metabolic disorders that a total of one in 1,000 to 2,500 newborns can be expected to have one. In certain ethnic populations, such as Ashkenazi Jews (Jews of central and eastern European ancestry), the rate of certain inherited metabolic disorders is much higher.
    ::一般来说,任何遗传的代谢紊乱一般都相当少见。 但是,有如此多不同的代谢紊乱,因此,每1 000至2 500个新生儿中就有1个可以预计有1个。 在某些少数民族人口中,如阿什克纳齐犹太人(中东欧血统犹太人),某些遗传的代谢紊乱率要高得多。

    Feature: Reliable Sources
    ::特征:可靠来源

    The most common of all known enzyme-deficiency disorders is glucose-6-phosphate-dehydrogenase — or G6PD — deficiency. In the U.S., the disorder occurs most often in African American males. The enzyme G6PD is needed to prevent the abnormal breakdown of red blood cells . Without the enzyme, red blood cells break down prematurely, resulting in anemia. 
    ::最常见的已知酶衰弱障碍是葡萄糖-6-磷酸酯-脱氢gena酶(即G6PD)缺乏。在美国,这种疾病最常发生在非裔美国人男性中。需要酶G6PD来防止红血细胞的异常破裂。没有酶,红血细胞过早破裂,导致贫血。

    Choose one of the following topics related to  G6PD deficiency:
    ::选择与G6PD缺陷有关的下列专题之一:

    • genetic basis
      ::遗传基
    • signs and symptoms
      ::症状和症状,以及症状和症状
    • diagnosis and treatment
      ::诊断和治疗的诊断及 治疗的诊断和治疗
    • worldwide distribution
      ::全世界分布分布情况

    Go online to further research the topic you chose . Find at least three sources of additional information that you think are reliable. Compare the information provided by the different sources, and identify any discrepancies among them. Do additional research as needed to try to find a reliable consensus view of the issue.
    ::上网进一步研究您选择的主题。 找到至少三个您认为可靠的补充信息来源。 比较不同来源提供的信息, 并找出它们之间的差异。 做必要的额外研究, 试图找到可靠的共识观点 。

    Summary
    ::摘要

    • Biochemical reactions are chemical reactions that take place inside of living things. The sum of all of the biochemical reactions in an organism is called metabolism.
      ::生物化学反应是生命中发生的化学反应,生物体中所有生物化学反应的总和被称为新陈代谢。
    • Metabolism includes catabolic reactions, which are energy-releasing (exothermic) reactions, as well as anabolic reactions, which are energy-absorbing (endothermic) reactions.
      ::新陈代谢包括代谢反应,即能量释放(异温)反应,以及新陈代谢反应,即吸收能量(末温)反应。
    • Most biochemical reactions need a biological catalyst called an enzyme to speed up the reaction. Enzymes reduce the amount of activation energy needed for the reaction to begin. Most enzymes are proteins that affect just one specific substance, which is called the enzyme's substrate.
      ::大部分生物化学反应都需要一种叫作酶的生物催化剂来加速反应。 酶减少了反应开始所需的活性能量。 大多数酶都是只影响一种特定物质的蛋白质,即酶的基质。
    • There are many inherited metabolic disorders in humans. Most of them are caused by a single defective or missing enzyme.
      ::人类中有许多遗传的代谢紊乱,其中多数是由单一的缺陷或缺失的酶引起的。

     Review
    ::回顾

    1. What are biochemical reactions?
    ::1. 什么是生化反应?

    2. Define metabolism.
    ::2. 界定新陈代谢。

    3. Compare and contrast catabolic and anabolic reactions.
    ::3. 比较和对比代谢和新陈代谢反应。

    4. Explain the role of enzymes in biochemical reactions.
    ::4. 解释酶在生化反应中的作用。

    5. What are enzyme-deficiency disorders?
    ::5. 什么是酶缺陷失调症?

    6. True or False:  Metabolism is one specific type of catabolism.
    ::6. 真实或假:代谢是一种特定类型的代谢。

    7 . True or False:  Biochemical reactions include catabolic and anabolic reactions.
    ::7. 真实或虚假:生化反应包括代谢和新陈代谢反应。

    8. Explain why the relatively low temperature of living things, along with  the low concentration of reactants, would cause biochemical reactions to occur very slowly in the body without enzymes.
    ::8. 解释为什么生物物的相对低温,加上反应剂的低浓度,将导致生物化学反应在身体中非常缓慢地发生,没有酶。

    9. Answer the following questions about what happens after you eat a sandwich.
    ::9. 回答以下关于吃三明治后会发生什么情况的问题。

    a. Pieces of the sandwich go into your stomach, where there are digestive enzymes that break down the food. Which type of metabolic reaction is this? Explain your answer.
    ::a. 三明治片片片进入你的胃,那里有消化酶分解食物,这是哪种代谢反应?解释你的答案。

    b. During  the process of digestion, some of the sandwich is broken down into glucose, which is then further broken down to release energy that your cells can use. Is this an exothermic or endothermic reaction? Explain your answer.
    ::b. 在消化过程中,一些三明治被分解成葡萄糖,然后进一步细分,释放出细胞可以使用的能量。这是过热反应还是内热反应?解释你的答复。

    c. The proteins in the cheese, meat, and bread in the sandwich are broken down into their component amino acids. Then your body uses those amino acids to build new proteins. Which kind of metabolic reaction is represented by the building of these new proteins? Explain your answer.
    ::c. 奶酪、肉类和面包中的蛋白质分解成其成分氨基酸,然后你的身体用氨基酸制造新的蛋白质,这些新蛋白质的形成代表何种代谢反应?解释你的答复。

    10. Explain why your body doesn’t just use one or two enzymes for all of its biochemical reactions.
    ::10. 解释为什么你的身体不只使用一两个酶来进行其所有生化反应。

    11. A ________ is the specific substance that an enzyme affects in a biochemical reaction.
    ::11. A 是指酶在生化反应中影响的具体物质。

     

    12. An enzyme is a biological _____________ .
    ::12. 酶是一种生物酶。

    a. catabolism
    ::a. 代谢

    b. form of activation energy
    ::b. 激活能量的形式

    c. catalyst
    ::c. 催化剂

    d. reactant
    ::d. 反应器

    Explore More
    ::探索更多

    Watch the video below to learn more about catabolic and anabolic reactions. 
    ::以了解更多关于代谢和新陈代谢反应的知识。

     

     

     

     

     

     

     

     


    The video below discusses the function of enzymes. 
    ::以下影片讨论酶的功能。