章节大纲

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    Crowd of runners participating in a marathon, showcasing their diverse attire and energy.

    Are we there yet?
    ::我们到了吗?

    As the weather warms up, the runners come out. Not just the casual joggers, but those really serious ones who actually enjoy running all 26.2 miles of a marathon. Prior to these races (and a lot of shorter ones), you hear a lot about carbo-loading. This practice involves eating a lot of starch in the days prior to the race. The starch is converted to glucose, which is normally used for biochemical energy . Excess glucose is stored as glycogen in liver and muscle tissue to be used when needed. If there is a lot of glycogen available, the muscles will have more biochemical energy to draw on when needed for the long run. The rest of us will just sit at the sidewalk restaurant eating our spaghetti and enjoying watching other people work hard.
    ::天气变暖后, 跑者就出来了。 不仅仅是临时的慢跑者, 而是那些真正享受过马拉松26.2英里跑步的非常严肃的人。 在这些比赛之前( 和许多较短的赛跑), 你听到很多关于汽车装车的问题。 这种做法涉及到在比赛前几天吃大量的淀粉。 淀粉被转换成葡萄糖, 通常用于生化能源。 多余的葡萄糖作为甘醇储存在肝脏和肌肉组织中, 必要时可以使用。 如果有大量的甘油, 肌肉将有更多生物化学能量, 在长期需要的时候可以吸收。 我们的其他人将坐在边道餐厅里, 吃我们的通食, 享受看别人努力工作。

    Polysaccharides
    ::复数

    Many simple sugars can combine by repeated reactions until a very large molecule is formed. A polysaccharide is a complex polymer formed from the linkage of many monomers . One of the best known polysaccharides is starch, the main form of energy storage in plants. Starch is a staple in most human diets. Foods such as corn, potatoes, rice, and wheat have high starch contents. Starch is made of glucose monomers and occurs in both straight-chain and branched forms. Amylose is the straight-chain form and consists of hundreds of linked glucose molecules. The branched form of starch is called amylopectin. In the small intestine, starch is hydrolyzed to form glucose. The glucose can then be converted to biochemical energy or stored for later use.
    ::许多简单的糖可以通过反复反应组合在一起,直到形成一个非常大的分子。聚沙英是一种复杂的聚合物,由许多单体的链接形成。最著名的聚沙英之一是恒星,这是植物中能源储存的主要形式。淀粉是大多数人类饮食中的主食。玉米、土豆、大米和小麦等食物含有高淀粉含量。淀粉由葡萄糖单体组成,在直链和分形形式中都存在。Amyloess是一种直链形式,由数百个相连的葡萄糖分子组成。星体的分支形式被称为线状切除素。在小肠中,淀粉被水解成葡萄糖的形式。然后,葡萄糖可以转化成生物化学能量,或者储存在以后使用。

    Structural formulas of amylose and amylopectin, components of starch in carbohydrates.

    Amylose and amylopectin are the two most common components of naturally occurring starch. Both consist of many glucose monomers connected into a polymer. Starch serves as energy storage in plants.
    ::Amyloess 和 ammyopetectin 是自然产生的淀粉的两个最常见的组成部分, 两者都包含许多与聚合物相连的葡萄糖单体。 Starch 充当植物的能量储存器。

    Glycogen is an even more highly branched polysaccharide of glucose monomers that serves a function of energy storage in animals. Glycogen is made and stored primarily in the cells of the liver and muscles.
    ::甘油是葡萄糖单体的更高度分支聚沙酸酯,与动物的能量储存作用相关,主要在肝脏和肌肉细胞中制造和储存甘油。

    Triple strand model of cellulose, illustrating its rod-like structure and hydrogen bonding.

    Glycogen is a branched polymer of glucose and serves as energy storage in animals.
    ::甘油是葡萄糖的分支聚合物,作为动物的能量储存。

    Cellulose is another polymer of glucose, consisting of anywhere from hundreds to over ten thousand monomers. It is the structural component of the cell walls of green plants and is the single most common organic molecule on Earth. Roughly 33% of all plant matter is cellulose. The linkage structure in cellulose is different than that of starch, and cellulose is indigestible except by a few microorganisms that live in the digestive tracts of cattle and termites. The figure below shows a triple strand of cellulose. There is no branching and the fibers adopt a very stiff rod-like structure with numerous between the fibers adding to its strength. Cellulose is the main component of paper, cardboard, and textiles made from cotton, linen, and other plant fibers.
    ::细胞素是另一个葡萄糖聚合物,由数百到1万多个单体组成的任何地方组成,它是绿色植物细胞壁的结构性组成部分,是地球上最常见的单一有机分子。大约33%的植物物质是纤维素。纤维素的连接结构不同于淀粉,纤维素的连接结构是无法消化的,只有生活在牛和白蚁消化道中的少数微生物除外。下图显示的是细胞素的三根。没有分枝,纤维采用非常硬的棒状结构,纤维在增加其强度的纤维之间有无数种。纤维素是用棉、线和其他植物纤维制成的纸张、纸板和纺织品的主要组成部分。

    A space-filling model of cellulose showing long glucose strands in a stiff structure.

    Cellulose is composed of very long strands of glucose monomers that are hydrogen bonded to one another. Cellulose is largely indigestible and comprises the cell walls of plants.
    ::纤维素由非常长的葡萄糖单体组成,这些单体相互连接氢,而纤维素大部分是不可稀释的,由植物的细胞壁组成。

     

     

    Review
    ::回顾

    1. What monomer composes all the polysaccharides mentioned?
      ::哪些单体组成了所有提到过的聚沙洲?
    2. What is the storage form of energy for plants?
      ::植物的能源储存形式是什么?
    3. What is the storage form of energy for animals?
      ::动物的能源储存形式是什么?