Section outline

  • General

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  • 电子运输

    What you will learn
    ::你会学到什么

    • The process of transport of high energy electrons along the electron transport chain
      ::沿电子运输链运输高能电子的过程
    • Creation of the chemiosmotic gradient through electron transport
      ::通过电子运输创造化学梯度
    • Production of ATP using the chemiosmotic gradient
      ::利用化学梯度生产ATP

    Different modes of transportation: airplane, truck, train, and boat.

    Train, truck, boat or plane?
    ::火车,卡车,船还是飞机?

    Ways to transport. To make ATP, energy must be ‘‘transported’’ - first from glucose to NADH , and then somehow passed to ATP. How is this done? With an electron transport chain.
    ::运输方式。要进行ATP, 能源必须先从葡萄糖运输到NADH, 然后再以某种方式传送到ATP。 如何完成? 使用电子运输链 。

    Cellular Respiration Stage III: Electron Transport
    ::细胞呼吸第三阶段:电子运输

    Electron transport is the final stage of aerobic respiration . In this stage, energy from NADH and FADH 2 , which result from and the , is transferred to ATP. Can you predict how this happens? ( Hint: How does electron transport occur in ?)
    ::电子传输是有氧呼吸的最后阶段。 在这一阶段,NADH 和 FADH2 的能量由 NADH 和 FADH2 产生并转移至 ATP 。 您能否预测这种情况是如何发生的 ? (提示:电子传输是如何发生的? )

    Transporting Electrons
    ::电子运输

    High-energy electrons are released from NADH and FADH 2 , and they move along electron transport chains , like those used in photosynthesis. The electron transport chains are on the inner membrane of the . As the high-energy electrons are transported along the chains, some of their energy is captured. This energy is used to pump hydrogen ions (from NADH and FADH 2 ) across the inner membrane, from the matrix into the intermembrane space. Electron transport in a mitochondrion is shown in the Figure .
    ::高能电子从NADH和FADH2中释放出来,它们沿着电子运输链移动,就像光合作用所用的那样。电子运输链位于该链的内膜上。随着高能电子沿着链条运输,它们的一些能量被捕捉。这种能量被用于将氢离子(NADH和FADH2)从矩阵中泵入内膜,从内膜到间隙空间。图中显示了在米托昆德里翁体内的电子运输。

    Mitochondrial electron transport chains showing electron flow and ATP production stages.
    The electron transport chains on the inner membrane of the mitochondrion carry out the last stage of cellular respiration.

    Making ATP
    ::建立ATP

    The pumping of hydrogen ions across the inner membrane creates a greater concentration of the ions in the intermembrane space than in the matrix. This chemiosmotic gradient causes the ions to flow back across the membrane into the matrix, where their concentration is lower. ATP synthase acts as a channel protein , helping the hydrogen ions to cross the membrane. It also acts as an , forming ATP from ADP and inorganic phosphate. After passing through the electron transport chain, the “spent” electrons combine with oxygen to form . This is why oxygen is needed; in the absence of oxygen, this process cannot occur.
    ::在内膜中抽取氢离子,使中间空间的离子比在矩阵中更加集中。这种化学梯度导致离子穿过膜回流回流到其浓度较低的矩阵中。ATP合成酶作为导道蛋白,帮助氢离子穿过膜。它也起到从ADP和无机磷酸盐形成ATP的作用。经过电子运输链后,“喷气”电子与氧合在一起形成。这就是为什么需要氧;在缺乏氧的情况下,这一过程不可能发生。

    DID YOU KNOW?
     In anaerobic environments, molecules other than oxygen like nitrate, iron(III), sulfate, and carbon dioxide are used that produce less energy as compared to aerobic respiration.
     

    How much ATP is produced? The two NADH produced in the cytoplasm produces 2 to 3 ATP each (4 to 6 total) by the electron transport system, the 8 NADH produced in the mitochondria produces three ATP each (24 total), and the 2 FADH 2 adds its electrons to the electron transport system at a lower level than NADH, so they produce two ATP each (4 total). This results in the formation of 34 ATP during the electron transport stage.
    ::生产了多少ATP?在细胞图层中生产的两个NADH通过电子运输系统每生产2-3ATP(共4-6人),在Mitochondria生产的8NADH每生产3ATP(共24人),2 FADH2在低于NADH的电子运输系统上增加电子,因此每生产2ATP(共4人),这导致在电子运输阶段形成34ATP。

     

     

    Summary
    ::摘要

    • Electron transport is the final stage of aerobic respiration. In this stage, energy from NADH and FADH 2 is transferred to ATP.
      ::电子运输是有氧呼吸的最后阶段,在这一阶段,NADH和FADH2的能源被转移到ATP。
    • During electron transport, energy is used to pump hydrogen ions across the mitochondrial inner membrane, from the matrix into the intermembrane space.
      ::在电子运输过程中,能源被用来泵出从矩阵到交错空间的微粒体内膜的氢离子。
    • A chemiosmotic gradient causes hydrogen ions to flow back across the mitochondrial membrane into the matrix, through ATP synthase, producing ATP.
      ::化学梯度导致氢离子通过ATP合成酶,通过生成ATP合成酶,穿过线粒体膜回流到矩阵中。

    Review
    ::回顾

    1. Summarize the overall task of Stage III of aerobic respiration.
      ::概述有氧呼吸第三阶段的总体任务。
    2. Explain the chemiosmotic gradient.
      ::解释一下化学梯度
    3. What is the maximum number of ATP molecules that can be produced during the electron transport stage of aerobic respiration?
      ::在有氧呼吸电子传输阶段能够产生的ATP分子的最大数量是多少?