Section outline

  • General

    Collapse all Expand all

  • 细胞呼吸过程

    Lesson
    ::经验教训

     

    Person with outstretched arms enjoying nature in a field with trees in the background.

     

    Why do you need to breathe?
    ::你为什么需要呼吸?

    Of course if you didn't breathe, you couldn't survive. Why do you need air to live? You need the gas oxygen to perform   to get  energy  from your food.
    ::当然,如果你没有呼吸,你活不下去。为什么你需要空气来生存?你需要气体氧气来工作才能从食物中获取能量。

    The Process of Cellular Respiration
    ::细胞呼吸过程

    Cellular respiration  is the process of extracting energy in the form of  ATP  from the  glucose  in the food you eat. How does cellular respiration happen inside of the  cell ? Cellular respiration is a three step process. Briefly:
    ::细胞呼吸是一种从食物中的葡萄糖中提取ATP形式的能量的过程。 细胞呼吸是如何在细胞内部发生的? 细胞呼吸是一个三步过程。 简而言之 :

    1. In stage one, glucose is broken down in the  cytoplasm  of the cell in a process called  glycolysis .
      ::在第一阶段,葡萄糖在细胞细胞的细胞图层中分解,其过程称为液解过程。
    1. In stage two, the  pyruvate  molecules are transported into the  mitochondria . The  mitochondria  are the   known as the energy "powerhouses" of the cells ( Figure   ). In the mitochondria, the pyruvate, which have been converted into a 2-carbon  molecule , enter the  Krebs cycle .  Notice that mitochondria have an inner membrane with many folds, called  cristae . These cristae greatly increase the membrane surface area where many of the cellular respiration reactions take place.
      ::在第二阶段,蒸发分子被传送到微粒体中。微粒体中被称为细胞的能量“电源 ” ( 图表 ) 。 在微粒体中, 微粒体被转化成2碳分子, 进入 Krebs 循环。 注意微粒体中含有许多折叠的内膜, 叫做 Crestae 。 这些晶体会大大增加细胞呼吸反应发生许多反应的薄膜表面面积 。
    1. In stage three, the energy in the energy carriers enters an  electron transport chain . During this step, this energy is used to produce ATP.
      ::在第三阶段,能源载体中的能源进入电子运输链。在这一步骤中,这种能源被用于生产ATP。

    Oxygen is needed to help the process of turning glucose into ATP. The initial step releases just two molecules of ATP for each glucose. The later steps release much more ATP.
    ::需要氧气来帮助将葡萄糖转化为ATP的过程。 最初的步骤只释放两种ATP分子, 每种葡萄糖。 以后的步骤释放更多的ATP分子。

    A mitochondrion showing its structure and components involved in ATP production.

     

    Most of the reactions of cellular respiration are carried out in the mitochondria.
    ::细胞呼吸的大多数反应都是在米托乔因德里亚进行的。

    The Reactants
    ::复发剂

    What goes into the cell? Oxygen and glucose are both  reactants  of cellular respiration. Oxygen enters the body when an  organism  breathes. Glucose enters the body when an organism eats.
    ::氧气和葡萄糖都是细胞呼吸的反应剂。当有机体呼吸时,氧气进入身体。当有机体食用时,葡萄糖进入身体。

    The Products
    ::产品

    What does the cell produce? The  products  of cellular respiration are carbon dioxide and water. Carbon dioxide is transported from your mitochondria out of your cell, to your  red blood cells , and back to your  lungs  to be exhaled. ATP is generated in the process. When one molecule of glucose is broken down, it can be converted to a net total of 36 or 38 molecules of ATP. This only occurs in the presence of oxygen.
    ::细胞产生什么? 细胞呼吸的产物是二氧化碳和水。 二氧化碳从你的细胞的mitocondria 转移到你的红细胞, 并返回你的肺里进行呼吸。 APT是在此过程中产生的。 当一个葡萄糖分子分解后, 它可以转换成ATP的总共36或38个分子。 这只有在氧气存在的情况下才会发生。

    The Chemical Reaction
    ::化学反应

    The overall  chemical reaction  for cellular respiration is one molecule of glucose (C 6 H 12 O 6 ) and six molecules of oxygen (O 2 ) yields six molecules of carbon dioxide (CO 2 ) and six molecules of water (H 2 O). Using chemical symbols the equation is represented as follows:
    ::细胞呼吸的总体化学反应是葡萄糖(C6H12O6)的一个分子,氧(O2)的六个分子产生6个二氧化碳(CO2)分子和6个水(H2O)分子。

    C 6 H 12 O 6  + 6O 2  → 6CO 2  + 6H 2 O
    ::C6H12O6 + 6O2 + 6CO2 + 6H2O

    ATP is generated during the process. Though this equation may not seem that complicated, cellular respiration is a series of chemical reactions divided into three stages: glycolysis, the Krebs cycle, and the electron transport chain.
    ::尽管这个方程式似乎并不复杂,但细胞呼吸是一系列化学反应,分为三个阶段:水解、Krebs循环和电子运输链。

    Glycolysis
    ::液溶解

    Stage one of cellular respiration is glycolysis. Glycolysis is the splitting, or  lysis  of glucose. Glycolysis converts the 6-carbon glucose into two 3-carbon  pyruvate  molecules. This process occurs in the cytoplasm of the cell, and it occurs in the presence or absence of oxygen. During glycolysis a small amount of  NADH  is made as are four ATP. Two ATP are used during this process, leaving a net gain of two ATP from glycolysis.  The NADH temporarily holds energy, which will be used in stage three.
    ::细胞呼吸的第一阶段是透析。 透析是葡萄糖的分解或解析。 透析将6-碳葡萄糖转换为2个3-碳激素分子。 这一过程发生在细胞的细胞图层中,在氧气存在或不存在的情况下发生。 微量的NADH在透析过程中与4个ATP一样,做了少量的NADH。 在这一过程中使用了2个ATP,从透析中净收益为2个ATP。 NADH暂时持有能源,将在第3阶段使用。

    The Krebs Cycle
    ::Krebs 轮盘周期

    In the presence of oxygen, under  aerobic  conditions, pyruvate enters the mitochondria to proceed into the Krebs cycle. The second stage of cellular respiration is the transfer of the energy in pyruvate, which is the energy initially in glucose, into two energy carriers, NADH and FADH 2 . A small amount of ATP is also made during this process. This process occurs in a continuous cycle, named after its discover, Hans Krebs. The Krebs cycle uses a 2-carbon molecule (acetyl-CoA) derived from pyruvate and produces carbon dioxide.
    ::在氧气存在的情况下,在有氧条件下,回旋剂进入mitochondria,进入Krebs循环。细胞呼吸的第二阶段是将Uruvate的能量(即最初以葡萄糖为能源)转移到两个能量载体NADH和FADH2。在这一过程中,还做了少量ATP。这一过程发生在一个连续的周期中,以发现Hans Krebs命名。Krebs循环使用源自Pyruvate的2碳分子(乙酰CoA),产生二氧化碳。

    The Electron Transport Chain
    ::电子运输链

    Stage three of cellular respiration is the use of NADH and FADH 2  to generate ATP. This occurs in two parts. First, the NADH and FADH 2  enter an electron transport chain, where their energy is used to pump, by  , protons (H + ) into the intermembrane space of mitochondria. This establishes a proton gradient across the inner membrane. These protons then flow down their  concentration gradient , moving back into the matrix by  facilitated diffusion . During this process, ATP is made by adding inorganic phosphate to ADP.  Most of the ATP produced during cellular respiration is made during this stage.
    ::细胞呼吸的第三阶段是使用NADH和FADH2来生成ATP。这分为两个部分:首先,NADH和FADH2进入电子运输链,其能量被质子(H+)用来泵入Mitochondria的中间空间。这在内膜上形成了质子梯度。这些质子随后通过加速扩散而向浓缩梯度下流,再回到矩阵中。在这一过程中,ATP通过在ADP中添加无机磷酸盐来进行。在这一阶段,细胞呼吸过程中产生的大部分ATP都是在细胞呼吸过程中产生的。

    For each glucose that starts cellular respiration, in the presence of oxygen (aerobic conditions), 36-38 ATP are generated. Without oxygen, under  anaerobic  conditions, much less (only two!) ATP are produced.
    ::对于每次开始细胞呼吸的葡萄糖,只要有氧(有氧条件),就会产生36-38 ATP。没有氧,在厌氧条件下,生产ATP的更少(只有两个! ) 。

    Summary
    ::摘要

    • Most of the steps of cellular respiration take place in the mitochondria.
      ::细胞呼吸的大多数步骤 发生在mitochondria。
    • Oxygen and glucose are both reactants in the process of cellular respiration.
      ::氧和葡萄糖都是细胞呼吸过程中的活性反应物。
    • The main product of cellular respiration is ATP; waste products include carbon dioxide and water.
      ::细胞呼吸的主要产品是ATP;废品包括二氧化碳和水。

    Explore More
    ::探索更多

    Use the resources below to answer the following questions
    ::利用以下资源回答下列问题:

    Explore More I
    ::探索更多

    • Krebs Cycle  at   (5:30)
      ::Krebs 周期在(5:30)
    1. Which types of cells have mitochondria?
      ::哪种细胞有中位分数?
    1. What is the cristae? Where does it occur? Why is this structure important?
      ::什么是日历?它在哪里发生?为什么这个结构很重要?
    1. What high energy electron carriers are produced by the Krebs cycle? Where do they carry their electrons?
      ::Krebs周期产生的高能量电子载体是什么?它们在哪里携带电子?
    1. What is the role of acetyl-CoA? Where does it fit into the Krebs cycle?
      ::乙酰CoA的作用是什么?它在哪里适合Krebs周期?
    1. How much ATP is made by the Krebs cycle for every molecule of Pyruvate that enters the cycle?
      ::进入周期的每个微粒分子的Krebs周期的ATP值是多少?

    Explore More II
    ::探索更多情况二

    • Electron Transport Chain  at   (3:50)
      ::电路链(3:50)
     
    1. What is the name of the protein complex that makes ATP?
      ::导致ATP的蛋白质综合体叫什么来着?
    1. What is the final electron acceptor at the end of the electron transport chain?
      ::电子运输链末端的最后电子接收器是什么?
    1. What is a "mobile transfer molecule"? What is their function?
      ::什么是移动转移分子?
    1. How is the hydrogen ion gradient formed?
      ::氢离子梯度是如何形成的?
    1. What is the purpose of the proton (hydrogen ion) gradient?
      ::质子离子梯度的目的是什么?

    Review
    ::回顾

    1. Where is glucose broken down to form ATP? What is this process called? Does this process need oxygen?
      ::葡萄糖分解到哪里形成 ATP ? 这个过程叫什么? 这个过程需要氧气吗 ?
    1. Write the chemical reaction for the overall process of cellular respiration.
      ::写下整个细胞呼吸过程的化学反应
    1. What is necessary for the Krebs cycle to proceed?
      ::Krebs周期的进行需要什么?
    1. What happens during the Krebs cycle?
      ::Krebs周期期间会发生什么?
    1. What is pyruvate?
      ::什么是回旋剂?
    1. What happens during the electron transport chain?
      ::在电子运输链中会发生什么?
    1. How is ATP made during the third stage of cellular respiration?
      ::ATP在细胞呼吸的第三阶段是如何做的?