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  • General

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  • 发酵

    What you will learn
    ::你会学到什么

    • How fermentation makes ATP using only the pathway
      ::发酵如何使 ATP 仅使用路径
    • What happens in lactic acid and
      ::在乳酸和

    Grapes, white and red wine glasses, and a barrel on a wooden surface.

    When you combine grapes and yeast, what have you begun to make?
    ::当你们将葡萄和酵母混合的时候,你们有什么收获呢?

    Wine. It may be slightly more complicated than that, but you need to start with grapes and yeast, and allow a natural fermentation process to occur. Essentially, this is respiration without oxygen.
    ::葡萄酒。 酒可能比这稍微复杂一些, 但你需要从葡萄和酵母开始, 并允许自然发酵过程。 基本上, 这是没有氧气的呼吸。

    Anaerobic Respiration: Fermentation
    ::厌氧呼吸:发酵

    An important way of making ATP without oxygen is called fermentation . During the 1850s, the renowned French chemist and microbiologist Louis Pasteur was the first person to demonstrate the role of microorganisms in the fermentation process. Most living things use aerobic respiration when oxygen is present to make ATP from glucose . But when oxygen is in short supply, some organisms use instead; this is true of some plants, , and many . In fact, certain microorganisms, like some bacteria, can only use anaerobic respiration and cannot survive in the presence of oxygen. People use these organisms to make yogurt, bread, wine, and biofuels. Human muscle also use fermentation. This occurs when muscle cells cannot get oxygen fast enough to meet their energy needs through aerobic respiration.
    ::在1850年代,著名的法国化学家和微生物学家路易斯·巴斯德(Louis Pasteur)是第一个展示微生物在发酵过程中作用的人。当氧气出现时,大多数生物都使用有氧呼吸法,用葡萄糖制成ATP。但是当氧气供应不足时,有些生物就使用,而有些生物则使用;某些植物、和许多植物就是这样。事实上,某些微生物,如某些细菌,只能使用厌氧呼吸,不能在氧气存在的情况下生存。人们用这些生物来制造酸奶、面包、葡萄酒和生物燃料。人类肌肉也使用发酵。当肌肉细胞不能通过氧呼吸来满足其能量需求时,就会发生这种情况。

    There are two types of fermentation: lactic acid fermentation and alcoholic fermentation. Both types of fermentation are described below. 
    ::发酵有两种类型:乙酸发酵和酒精发酵。

     

     

    Lactic Acid Fermentation
    ::电法酸发酵

    In lactic acid fermentation , pyruvate (also known as pyruvic acid) from glycolysis changes to lactic acid. This is shown in the Figure . In the process, NAD + forms from NADH . NAD + , in turn, lets glycolysis continue. This results in additional molecules of ATP. This type of fermentation is carried out by the bacteria in yogurt. It is also used by your own muscle cells when they are using more oxygen than the body can replenish through circulation, usually during intense .
    ::在乳酸发酵中,从玻璃解析变化到乳酸的回旋酸(也称为皮鲁维茨酸),这在图中显示。在这个过程中,NADH 的NAD+ 表格。NAD+ 反过来,则继续以液解。这导致ATP 的额外分子。这种发酵是由酸酸中的细菌进行的。当肌肉细胞使用氧量超过身体通过循环(通常在强度下)进行补充时,也使用这种发酵。

    Depiction of lactic acid fermentation showing conversion from pyruvate to lactic acid.
    Lactic acid fermentation produces lactic acid and NAD + . The NAD + cycles back to allow glycolysis to continue so more ATP is made. Each circle represents a carbon atom.

    Alcoholic Fermentation
    ::酒精发酵

    In alcoholic fermentation ,  pyruvate changes to alcohol and carbon dioxide. This is shown in the Figure . NAD + also forms from NADH, allowing glycolysis to continue making ATP. This type of fermentation is carried out by plants, yeasts and some bacteria. It is used to make bread, wine, and biofuels.
    ::在酒精发酵中,酒精和二氧化碳的加速变化,如图所示。NAD+也是来自NADH的,允许水解继续产生ATP,这种发酵是由植物、酵母和一些细菌进行的,用来制造面包、葡萄酒和生物燃料。

    Flowchart showing alcoholic fermentation: pyruvate converts to ethanol and CO2, with NAD+ regeneration.
    Alcoholic fermentation produces ethanol and NAD+. The NAD+ allows glycolysis to continue making ATP.

    Have your parents ever put corn in the gas tank of their car? They did if they used gas containing ethanol. Ethanol is produced by alcoholic fermentation of the glucose in corn or other plants. This type of fermentation also explains why bread dough rises. Yeasts in bread dough use alcoholic fermentation and produce carbon dioxide gas. The gas forms bubbles in the dough, which cause the dough to expand. The bubbles also leave small holes in the bread after it bakes, making the bread light and fluffy. Do you see the small holes in the slice of bread in the Figure ?
    ::你的父母曾把玉米放进他们的汽车的油箱里吗?他们曾用过含乙醇的气体吗?乙醇是由玉米或其他植物中的葡萄糖的酒精发酵产生的。这种发酵也解释了面包面团上升的原因。面包面团中的野兽使用酒精发酵和产生二氧化碳气体。气体在面团中形成泡沫,导致面团膨胀。泡沫在面包烘烤后还留下小洞,使面包光亮和毛毛发。你是否看到图中面包片中的小洞?

    Sliced bread on a wooden platter, showing small holes caused by carbon dioxide bubbles.
    The small holes in bread are formed by bubbles of carbon dioxide gas. The gas was produced by alcoholic fermentation carried out by yeast.

     

     

     

     

    DID YOU KNOW?
    Have you ever run a race and noticed that your feel tired and sore afterward? For a long time it was hypothesized that this was a result of lactic acid accumulation in muscles. More recent studies do not support this initial hypothesis and instead suggest that the soreness experienced after intense exercise is related to the healing process of tiny muscle tears that occur as a result of strenuous exertion.
     

     

    Summary
    ::摘要

    • Fermentation makes ATP without oxygen, which involves glycolysis only.
      ::发酵使ATP没有氧气,这只涉及液解。
    • Fermentation recycles NAD + , and produces 2 ATPs.
      ::发酵回收了NAD+,并生产了两个ATP。
    • In lactic acid fermentation,  pyruvate from glycolysis changes to lactic acid. This type of fermentation is carried out by the bacteria in yogurt, and by your own muscle cells.
      ::在乳酸发酵中,从玻璃解析变化到乳酸的回旋剂。这种发酵是由酸奶中的细菌和你自己的肌肉细胞进行的。
    • In alcoholic fermentation, pyruvate  changes to alcohol and carbon dioxide. This type of fermentation is carried out by plants, yeasts and some bacteria.
      ::在酒精发酵中,酒精和二氧化碳的加速变化,这种发酵是由植物、酵母和一些细菌进行的。

    Review
    ::回顾

    1. What is fermentation?
      ::什么是发酵?
    2. Name two types of fermentation.
      ::列出两种发酵类型。
    3. What is the main advantage of aerobic respiration? Of anaerobic respiration?
      ::有氧呼吸的主要好处是什么?无氧呼吸的主要好处是什么?
    4. What process produces fuel for motor vehicles from living plant products? What is the waste product of this process?
      ::用活植物产品为机动车辆生产燃料的流程是什么?这一流程的废物产物是什么?
    5. Compare and contrast lactic acid fermentation and alcoholic fermentation. Include examples of organisms that use each type of fermentation.
      ::比较和对比白酸发酵和酒精发酵,包括使用每种发酵类型的生物的例子。