细胞呼吸
Section outline
-
Bring on the S'mores!
::带上S'mores!This inviting camp fire can be used for both heat and light. Heat and light are two forms of energy that are released when a fuel like wood is burned. The of living things also get energy by "burning." They "burn" glucose in a process called cellular respiration.
::热能和光是两种能源形式。热能和光是燃烧木柴等燃料时释放出来的能源。活物也会通过“燃烧”获得能量。它们“燃烧”葡萄糖的过程叫做细胞呼吸。What Is Cellular Respiration?
::什么是细胞呼吸?Cellular respiration is the process by which living cells break down glucose molecules and release energy. The process is similar to burning, although it doesn’t produce light or intense heat as a campfire does. This is because cellular respiration releases the energy in glucose slowly and in many small steps. It uses the energy released to form molecules of ATP , the energy-carrying molecules that cells use to power biochemical processes. Cellular respiration involves many chemical reactions , but they can all be summed up with this chemical equation :
::细胞呼吸是活细胞分解葡萄糖分子和释放能量的过程。 这个过程与燃烧相似, 虽然它不会像营火那样产生光或高温。 这是因为细胞呼吸会缓慢地释放出葡萄糖中的能量, 并且在许多小步骤中释放出能量。 它利用释放的能量形成ATP的分子, 即细胞用来推动生化过程的能量携带分子。 细胞呼吸会有许多化学反应, 但是它们都可以用化学公式来概括:C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + Chemical Energy (in ATP)
::C6H12O6 + 6O2 + 6O2 + 6CO2 + 6H2O+ 化学能源(在ATP中)In words, the equation shows that glucose ( C 6 H 12 O 6 ) and oxygen ( O 2 ) react to form carbon dioxide ( CO 2 ) and ( H 2 O ), releasing energy in the process. Because oxygen is required for cellular respiration, it is an aerobic process.
::换句话说,方程式表明葡萄糖(C6H12O6)和氧氧(O2)会形成二氧化碳(CO2)和(H2O),在过程中释放能量。由于细胞呼吸需要氧,因此这是一种有氧过程。Cellular respiration occurs in the cells of all living things, both autotrophs and heterotrophs . All of them burn glucose to form ATP. The reactions of cellular respiration can be grouped into three stages: , the (also called the citric acid cycle), and . The figure gives an overview of these three stages, which are also described in detail below.
::细胞呼吸发生在所有生物细胞的细胞中,包括自养和血化细胞。所有细胞都是燃烧的葡萄糖,形成ATP。细胞呼吸的反应可以分为三个阶段:......(也称为柠檬酸循环)和。图中概述了这三个阶段,下文也对此作了详细说明。Cellular respiration takes place in the stages shown here. The process begins with a molecule of glucose, which has six carbon atoms. What happens to each of these atoms of carbon?
::细胞呼吸在此处显示的阶段进行。 过程从一个有六个碳原子的葡萄糖分子开始。 这些碳原子的每一个会怎样呢 ?Cellular Respiration Stage I: Glycolysis
::细胞呼吸第一阶段:液解The first stage of cellular respiration is glycolysis, which happens in the cytosol of the cytoplasm .
::细胞呼吸的第一阶段是气解, 发生于细胞顶层的细胞索中。Splitting Glucose
::分割葡萄糖The word glycolysis means “glucose splitting,” which is exactly what happens in this stage. split a molecule of glucose into two molecules of pyruvate (also known as pyruvic acid). This occurs in several steps, as shown in the diagram.
::糖分解一词的意思是“葡萄糖分解 ” , 这正是目前阶段发生的情况。 将葡萄糖分子分裂成两种气溶胶分子(也称为pyruvic酸 ) 。 这在几个步骤中发生,如图表所示。
In glycolysis, glucose (C6) is split into two 3-carbon (C3) pyruvate molecules. This releases energy, which is transferred to ATP. How many ATP molecules are made during this stage of cellular respiration?
::在液解中,葡萄糖(C6)被分成两个3碳(C3)气压分子,释放能量,这种能量被转移到ATP。在细胞呼吸的这一阶段,有多少ATP分子被制造出来?Results of Glycolysis
::液分解结果Energy is needed at the start of glycolysis to split the glucose molecule into two pyruvate molecules. These two molecules go on to stage II of cellular respiration. The energy needed to split glucose is provided by two molecules of ATP. As glycolysis proceeds, energy is released, and the energy is used to make four molecules of ATP. As a result, there is a net gain of two ATP molecules during glycolysis. During this stage, high-energy electrons are also transferred to molecules of NAD + to produce two molecules of NADH , another energy-carrying molecule. NADH is used in stage III of cellular respiration to make more ATP.
::溶解开始时需要能量,以便将葡萄糖分子分成两个蒸发分子。这两个分子继续进入细胞呼吸的第二阶段。分裂葡萄糖所需的能量由ATP的两个分子提供。随着溶解收益的释放,能量被释放,能量被用来制造ATP的四个分子。结果,在解析过程中有两个ATP分子的净收益。在这一阶段,高能电子还被转移到NAD+的分子中,以产生两个NADH的分子,另一个能量携带分子。NADH被用于细胞呼吸的第三阶段,以产生更多的ATP。Structure of the Mitochondrion
::密托贡德里群岛结构Before you read about the last two stages of cellular respiration, you need to know more about the , where these two stages take place. A diagram of a mitochondrion is shown .
::在读取细胞呼吸的最后两个阶段之前, 您需要了解更多关于这两个阶段发生地点的信息。 显示的是一个米托昆卓图 。
The structure of a mitochondrion is defined by an inner and outer membrane. This structure plays an important role in aerobic respiration.
::线粒体的结构由内外部膜界定,在有氧呼吸中起着重要作用。As you can see from the figure, a mitochondrion has an inner and outer membrane. The space between the inner and outer membrane is called the intermembrane space . The space enclosed by the inner membrane is called the matrix . The second stage of cellular respiration (the Krebs cycle) takes place in the matrix. The third stage (electron transport) happens on the inner membrane.
::从图中可以看出,米托昆德里翁有内外膜。内外膜之间的空间称为间距空间。内膜所封闭的空间称为矩阵。细胞呼吸的第二阶段(Krebs循环)在矩阵中发生。第三级(电子传输)发生在内膜上。Cellular Respiration Stage II: The Krebs Cycle
::细胞呼吸第二阶段:Krebs循环Recall that glycolysis produces two molecules of pyruvate (pyruvic acid). These molecules enter the matrix of a mitochondrion, where they start the Krebs cycle . The reactions that occur next are shown in the figure.
::提醒注意, 晶体解解析产生两种微积酸分子。 这些分子会进入米托昆德里翁的矩阵中, 开始 Krebs 循环。 下一种反应将在图中显示 。
The Krebs cycle starts with pyruvic acid from glycolysis. Each small circle in the diagram represents one carbon atom. For example, citric acid is a six carbon molecule, and OAA (oxaloacetate) is a four carbon molecule. Follow what happens to the carbon atoms as the cycle proceeds. In one turn through the cycle, how many molecules of ATP are produced? How many molecules of NADH and FADH2 are produced?
::Krebs 周期从玻璃解析的pyruvic酸开始。 图表中的每个小圆圈代表一个碳原子。 例如, 柠檬酸是一个6个碳分子, OAA( oxloacetate) 是一个4个碳分子。 跟踪碳原子在循环过程中发生的情况。 在循环中转一转, 产生多少个ATP分子? NADH 和 FADH2 的分子是多少?Before the Krebs cycle begins, pyruvic acid, which has three carbon atoms, is split apart and combined with an enzyme known as CoA, which stands for coenzyme A. The product of this reaction is a two-carbon molecule called acetyl-CoA. The third carbon from pyruvic acid combines with oxygen to form carbon dioxide, which is released as a waste product. High-energy electrons are also released and captured in NADH.
::在Krebs循环开始之前,含有三个碳原子的pyruvic酸被分离,与一种称为 CoA的酶(CoA)合在一起,该酶代表Cozyme A。 这种反应的产物是一种叫做乙酰CoA的双碳分子。 Pyruvic酸的第三个碳与氧结合,形成二氧化碳,作为废品释放。高能电子也在NADH中释放和捕捉。Steps of the Krebs Cycle
::Krebs 周期步骤The Krebs cycle itself actually begins when acetyl-CoA combines with a four-carbon molecule called OAA (oxaloacetate) (see figure ). This produces citric acid, which has six carbon atoms. This is why the Krebs cycle is also called the citric acid cycle.
::Krebs 循环本身实际上始于乙基- 可乐与一种四碳分子“OAA”(oxaloacetate)(见图 ) 结合时。 这会产生柠檬酸, 它有六个碳原子。 这就是为什么Krebs循环也被称为柠檬酸循环的原因。After citric acid forms, it goes through a series of reactions that release energy. The energy is captured in molecules of NADH, ATP, and FADH 2 , another energy-carrying compound. Carbon dioxide is also released as a waste product of these reactions.
::在柠檬酸形式之后,它经历了释放能量的一系列反应。 能量被NADH、ATP和FADH2的分子所捕捉。 另一种含有能量的化合物。 二氧化碳也作为这些反应的废物产物释放出来。The final step of the Krebs cycle regenerates OAA, the molecule that began the Krebs cycle. This molecule is needed for the next turn through the cycle. Two turns are needed because glycolysis produces two pyruvic acid molecules when it splits glucose.
::Krebs 循环周期的最后一步是 OAA , 开始 Krebs 循环的分子 。 此分子在周期的下一个转弯中需要该分子。 需要两个转弯, 因为它在分解葡萄糖时会产生两个 pyruvic 酸分子 。Results of the Krebs Cycle
::Krebs 周期结果After the second turn through the Krebs cycle, the original glucose molecule has been broken down completely. All six of its carbon atoms have combined with oxygen to form carbon dioxide. The energy from its chemical bonds has been stored in a total of 16 energy-carrier molecules. These molecules are:
::在第二次翻转 Krebs 周期后, 原葡萄糖分子已经完全分解。 其全部六个碳原子都与氧合在一起形成二氧化碳。 化学键的能量已经储存在总共16个能量载体分子中。 这些分子是:-
four ATP (including two from glycolysis)
::四份ATP(包括二份液解) -
ten NADH (including two from glycolysis)
::10 NADH(包括2个来自水解) -
two FADH
2
::两架FADH2
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 cellular respiration. In this stage, energy from NADH and FADH 2 , which result from the Krebs cycle, is transferred to ATP.
::电子传输是细胞呼吸的最后阶段,在这一阶段,由Krebs循环产生的NADH和FADH2的能量被转移到ATP。Transporting Electrons
::电子运输Electron transport is the third stage of cellular respiration . It is illustrated in the diagram . During this stage, high-energy electrons are released from NADH and FADH 2 , and they move along electron-transport chains on the inner membrane of the mitochondrion. An electron-transport chain is a series of molecules that transfer electrons from molecule to molecule by chemical reactions. Some of the energy from the electrons is used to pump hydrogen ions (H + ) across the inner membrane, from the matrix into the intermembrane space. This ion transfer creates an that drives the synthesis of ATP.
::电子传输是细胞呼吸的第三个阶段。图中说明了这一点。在这一阶段,从NADH和FADH2释放出高能电子,这些电子沿着电子运输链在米托贡德里翁的内膜上移动。电子传输链是一系列分子,通过化学反应将电子从分子转移到分子中。电子中的一些能量被用于将氢离子(H+)泵过内膜,从矩阵到隔膜空间。这种离子传输可以驱动ATP的合成。
Electron-transport chains on the inner membrane of the mitochondrion carry out the last stage of cellular respiration.
::线粒体内膜上的电子运输链 进行细胞呼吸的最后阶段Making ATP
::建立ATPThe pumping of hydrogen ions across the inner membrane creates a greater concentration of the ions in the intermembrane space than in the matrix. This 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 cross the membrane. It also acts as an enzyme, forming ATP from ADP and inorganic phosphate in a process called oxidative phosphorylation. After passing through the electron-transport chain, the “spent” electrons combine with oxygen to form water.
::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。这种梯度导致离子穿过膜回流到其浓度较低的矩阵中。ATP合成酶起到导道蛋白的作用,帮助氢离子穿过膜。它也起到酶的作用,形成ADP的ATP和无机磷酸盐,其过程被称为氧化磷酸。经过电子运输链后,“喷射”电子与氧结合形成水。How Much ATP?
::多少ATP? 多少ATP? 多少ATP?You have seen how the three stages of aerobic respiration use the energy in glucose to make ATP. How much ATP is produced in all three stages combined? Glycolysis produces two ATP molecules, and the Krebs cycle produces two more. Electron transport begins with several molecules of NADH and FADH 2 from the Krebs cycle and transfers their energy into as many as 34 more ATP molecules. All told, then, up to 38 molecules of ATP can be produced from just one molecule of glucose in the process of cellular respiration.
::您已经看到有氧呼吸的三个阶段是如何利用葡萄糖中的能量来制造ATP的。 在所有三个阶段中,ATP生产了多少? 液解作用产生两个ATP分子, Krebs 循环产生另外两个分子。 电子传输从Krebs循环的NADH和FADH2的数个分子开始,并将它们的能量转移到多达34个ATP分子中。 然后,所有这一切告诉我们,在细胞呼吸过程中,最多38个ATP分子都可以从一个葡萄糖分子中产生。Summary
::摘要-
Cellular respiration is the aerobic process by which living cells break down glucose molecules, release energy, and form molecules of ATP.
Generally speaking
, this three-stage process involves glucose and oxygen reacting to form carbon dioxide and water.
::细胞呼吸是活细胞分解葡萄糖分子、释放能量和形成ATP分子的有氧过程。 一般来说,这三阶段过程包括葡萄糖和氧气反应以形成二氧化碳和水。 -
The first stage of cellullar respiration, called glycolysis, takes place in the cytoplasm. In this step, enzymes split a molecule of glucose into two molecules of pyruvate, which releases energy that is transferred to ATP.
::细胞素呼吸的第一阶段,即所谓的淋巴解析,发生在细胞图层中。在这一步骤中,酶将葡萄糖的分子分裂成两种气溶胶分子,释放向ATP转移的能量。 -
The organelle called a mitochondrion is the site of the other two stages of cellular respiration. The mitochondrion has an inner and outer membrane separated by an intermembrane space, and the inner membrane encloses a space called the matrix.
::单心膜是细胞呼吸的其他两个阶段的场所。 单心膜有一个内外膜,由间隔空间隔开,内膜则包含一个称为矩阵的空间。 -
The second stage of cellular respiration, called the Krebs cycle, takes place in the matrix of a mitochondrion. During this stage, two turns through the cycle result in all of the carbon atoms from the two pyruvate molecules forming carbon dioxide and the energy from their chemical bonds being stored in a total of 16 energy-carrying molecules (including four from glycolysis)
.
::细胞呼吸的第二阶段,即叫做Krebs循环的细胞呼吸的第二阶段,在米托昆德里翁的基质中进行。在这个阶段,两轮循环的结果是,形成二氧化碳的两个闪烁分子的所有碳原子及其化学键的能量都储存在总共16个含有能量的分子中(包括4个来自玻璃解析的分子)。 -
The third and final stage of cellular respiration, called electron transport, takes place on the inner membrane of the mitochondrion. Electrons are transported from molecule to molecule down an electron-transport chain
. Some of the energy from the electrons is used to pump hydrogen ions
across the membrane, creating an electrochemical gradient that drives the synthesis of many more molecules of ATP.
::细胞呼吸的第三阶段也是最后阶段,即称为电子传输,发生在米托昆德里翁的内膜上,电子从分子转移到分子到电子运输链下。电子产生的一些能量被用于泵打膜的氢离子,形成电化学梯度,驱动APT中更多分子的合成。 -
In all three stages of cellular respiration combined, as many as 38 molecules of ATP are produced from just one molecule of glucose.
::在细胞呼吸的所有三个阶段合在一起,最多38个ATP分子仅从一个葡萄糖分子中产生。
Review
::回顾1. What is the purpose of cellular respiration? Provide a concise summary of the process.
::1. 细胞呼吸的目的是什么?提供过程的简明摘要。2. State what happens during glycolysis.
::2. 说明在水解过程中发生的情况。3. Describe the structure of a mitochondrion.
::3. 描述米托克特里翁的结构。4. Outline the steps of the Krebs cycle.
::4. 概述Krebs周期的步骤。5. What happens during the electron transport stage of cellular respiration?
::5. 细胞呼吸电子传输阶段发生什么情况?6. How many molecules of ATP can be produced from one molecule of glucose during all three stages of cellular respiration combined?
::6. 在细胞呼吸的所有三个阶段结合使用一个葡萄糖分子可产生多少ATP分子?7. Do plants undergo cellular respiration? Why or why not?
::7. 植物是否进行细胞呼吸?为什么或为什么没有?8. Explain why the process of cellular respiration described in this section is considered aerobic.
::8. 解释本节所述细胞呼吸过程为何被视为有氧。9. Name three energy-carrying molecules involved in cellular respiration.
::9. 列出参与细胞呼吸的三个含有能量的分子。10. Energy is stored within chemical _________ within a glucose molecule.
::10. 能量储存在葡萄糖分子中的化学 内。11. True or False: During cellular respiration, NADH and ATP are used to make glucose.
::11. 真实或假:在细胞呼吸期间,NADH和ATP被用来制造葡萄糖。12. True or False: ATP synthase acts as both an enzyme and a channel protein.
::12. 真实或假:ATP合成酶既是酶,又是渠道蛋白质。13. True or False: The carbons from glucose end up in ATP molecules at the end of cellular respiration.
::13. 真实的或假的:葡萄糖的碳最终会在细胞呼吸结束时进入ATP分子。14. Which stage of aerobic cellular respiration produces the most ATP?
::14. 哪个有氧细胞呼吸阶段产生最大ATP?Explore More
::探索更多Although this animation doesn't include any words , it illustrates the processes which occur inside a mitochondrion, including the production of AT P.
::虽然这幅动画不包含任何单词, 但它展示了在线粒体内发生的过程, 包括ATP的制作过程。
Watch the video below for a detailed overview of cellular respiration.
::观看下面的录像,以详细概述细胞呼吸。 -
four ATP (including two from glycolysis)
