3.4 碳水合物
Section outline
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The Cellulose of Our Lives
::我们生命的纤维素Where would we be without our jeans? They have been the go-to pants for many people for decades, and they are still as popular as ever. Jeans are made of denim, a type of cotton fabric. Cotton is a soft, fluffy fiber that grows in a protective case around the seeds of cotton plants. The fiber is almost pure cellulose . Cellulose is the single most abundant biochemical compound found in Earth's living things, and it's one of several types of carbohydrates.
::没有牛仔裤,我们又会到哪里去?它们已经是许多人的裤子了几十年,它们仍然象以往一样受欢迎。 Jeans是用棉织品Denim制成的。 棉花是一种软的、毛纤维,在棉花植物种子周围的一种保护性案例中生长。 纤维几乎是纯纤维素。 纤维是地球上生物物质中唯一最丰富的生化化合物,也是几种碳水化合物之一。What Are Carbohydrates?
::什么是碳水化合物?Carbohydrates are the most common class of biochemical compounds. They include sugars and starches. Carbohydrates are used to provide or store energy , among other uses. Like most biochemical compounds, carbohydrates are built of small repeating units, or monomers , which form bonds with each other to make larger molecules, called polymers . In the case of carbohydrates, the small repeating units are known as monosaccharides . Each monosaccharide consists of six carbon atoms, as shown in the model of the monosaccharide glucose .
::碳水化合物是最常见的生化化合物类别,包括糖和淀粉;碳水化合物用于提供或储存能源等用途;与大多数生化化合物一样,碳水化合物由小的重复体或单体组成,它们彼此形成联系,制造更大的分子,称为聚合物;就碳水化合物而言,小的重复体称为单沙酸盐;如单沙酸甘蔗模型所示,每种单沙酸由6个碳原子组成。The six black balls in this model of the monosaccharide glucose represent carbon atoms.
::这个模型中的六颗黑球 代表碳原子Sugars
::糖糖Sugars are the general name for sweet, short-chain, soluble carbohydrates, which are found in many foods. Their function in living things is to provide energy. The simplest sugars consist of a single monosaccharide. They include glucose, fructose, and galactose. Glucose is a simple sugar that is used for energy by the of living things. Fructose is a simple sugar found in fruits , and galactose is a simple sugar found in milk. Their chemical structures are shown in the figure below. All monosaccharides have the formula C 6 H 12 O 6 .
::糖是甜的、短链的、可溶解的碳水化合物的一般名称,它们在许多食物中都有,它们的作用是提供能量。它们存在于生物中的功能是提供能量。最简单的糖由单一的单沙酸糖组成。它们包括葡萄糖、fructose 和 galacactose。甘蔗是一种简单的糖,通过活物的能量来使用。甘蔗是一种简单的糖,在水果中可以找到一种简单的糖,而甘油在牛奶中也可以找到一种简单的糖。它们的化学结构在下图中显示。所有单一的甘蔗都配有C6H12O6的配方的C6H12O6。Other sugars contain two monosaccharide molecules and are called disaccharides . These include sucrose (table sugar), maltose, and lactose , which are shown below. S ucrose is composed of one fructose molecule and one glucose molecule, maltose is composed of two glucose molecules, and lactose is composed of one glucose molecule and one galactose molecule. Lact ose occurs naturally in milk. Some people are lactose intolerant because they can't digest lactose. If they drink milk, it causes gas, cramps, and other unpleasant symptoms, unless the milk has been processed to remove the lactose.
::其他的糖含有两种单沙律分子,称为分解体。这些糖包括苏克罗塞(可溶糖)、麦芽糖和乳糖,如下文所示。苏克罗塞由一种软糖分子和一种葡萄糖分子组成,麦芽糖由两种葡萄糖分子组成,乳糖由一种葡萄糖分子和一种雌性糖分子组成。乳糖在牛奶中自然产生。有些人乳糖不耐受,因为他们不能消化乳糖。如果他们喝牛奶,就会引起气、抽筋和其他不愉快的症状,除非牛奶经过加工去除乳糖。Complex Carbohydrates
::复合碳水合物Some carbohydrates consist of hundreds — or even thousands! — of monosaccharides bonded together in long chains. These carbohydrates are called polysaccharides ("many saccharides"). Polysaccharides are also referred to as complex carbohydrates. Complex carbohydrates that are found in living things include starch , glycogen, cellulose, and chitin . Each type of complex carbohydrate has different functions in living organisms , but they generally either store energy or make up certain structures in living things.
::有些碳水化合物由成百上千甚至数千个单体碳氢化合物组成,它们由长链链中捆绑在一起的单体碳水化合物组成,这些碳水化合物称为聚体碳酸盐(“许多碳水化合物”),这些聚体碳水化合物也被称为复杂的碳水化合物,在生物体中发现的复杂碳水化合物包括淀粉、甘醇、纤维素和。每一种复杂的碳水化合物在生物体中都有不同的功能,但它们通常要么储存能量,要么构成某些生物体结构。Starch
::星空Starch is a complex carbohydrate that is made by plants to store energy. For example, the potatoes pictured are packed full of starches that consist mainly of repeating units of glucose and other simple sugars. The leaves of potato plants make sugars by , and the sugars are carried to underground tubers where they are stored as starch. When we eat starchy foods such as potatoes, the starches are broken down by our into sugars, which provide our cells with energy. Starches are easily and quickly digested with the help of digestive such as amylase , which is found in the saliva . If you chew a starchy saltine cracker for several minutes, you may start to taste the sugars released as the starch is digested.
::淀粉是一种复杂的碳水化合物,由植物制造,储存能量。例如,土豆图片中满满了恒星,主要是葡萄糖和其他简单的糖。土豆植物的叶子制成糖,糖被带至地下管子,作为淀粉存放。当我们吃像土豆这样的淀粉食物时,淀粉被我们粉碎成糖,这为我们提供了细胞的能量。在盐碱中发现的氨酸盐等消化剂的帮助下,淀粉很容易迅速消化。如果你嚼了几分钟的恒星盐饼干,你可能会开始尝到当淀粉被消化时释放的糖。Potatoes are starch-filled tubers of potato plants. They are harvested by digging them up from underground.
::土豆是土豆植物的淀粉管,从地下挖出来,收获土豆。Glycogen
::甘烃原do not store energy as starch. Instead, animals store extra energy as the complex carbohydrate glycogen. Glycogen is a polysaccharide of glucose. It serves as a form of energy storage in (as well as animals), and it is the main storage form of glucose in the . In humans, glycogen is made and stored primarily in the cells of the liver and . When energy is needed from either storage depot, the glycogen is broken down to glucose for use by cells. Muscle glycogen is converted to glucose for use by muscle cells, and liver glycogen is converted to glucose for use throughout the rest of the body. Glycogen forms an energy reserve that can be quickly mobilized to meet a sudden need for glucose, but one that is less compact than the energy reserves of , which are the primary form of energy storage in animals.
::相反,动物储存的能量是作为复合碳水化合物甘蓝的复合碳水化合物。 甘醇是甘蔗糖的一种聚沙酸盐。 它是一种在(以及动物)中储存能量的形式,是甘蔗糖的主要储存形式。 在人类中,主要在肝脏细胞中制造和储存甘油。 当需要两个储存库的能量时,将甘醇分解为葡萄糖,供细胞使用。 肌肉甘醇被转化成葡萄糖,供肌肉细胞使用,肝糖素被转化成甘蔗糖,供整个身体的其余部分使用。 甘醇形成一种能量储备,可以迅速调动以满足对甘蔗的突然需求,但一种能量储备比能量储量弱,后者是动物能源储存的主要形式。Glycogen plays a critical part in the of glucose levels in the . When blood glucose levels rise too high, excess glucose can be stored in the liver by converting it to glycogen. When glucose levels in the blood fall too low, glycogen in the liver can be broken down to glucose and released into the blood.
::甘油在葡萄糖水平中起着关键作用。当血糖水平升高太高时,将多余的葡萄糖转化为甘油,可以储存在肝脏中;当血液中的葡萄糖水平过低时,肝脏中的甘油可以细分为葡萄糖,并释放到血液中。Cellulose
::纤维素Cellulose is a p olysaccharide consisting of a linear chain of several hundred to many thousands of linked glucose units. Cellulose is an important structural component of the cell walls of plants and many . Human uses of cellulose include the production of cardboard and paper, which consist mostly of cellulose from wood and cotton. The cotton fibers pictured are about 90 percent cellulose.
::细胞素是一种聚沙化物,由数百至数千个相连的葡萄糖单位组成的线性链条组成。细胞素是植物和许多植物细胞壁的重要结构组成部分。人类对纤维素的用途包括生产纸板和纸板,大部分由木材和棉花的纤维组成。所拍摄的棉花纤维约为90%的纤维素。Cotton fibers represent the purest natural form of cellulose, containing more than 90 percent of this polysaccharide.
::棉花纤维是纤维素最纯天然的天然形式,含有90%以上的这种聚沙酸酯。Certain animals, including termites and ruminants such as cows, can digest cellulose with the help of microorganisms that live in their gut. Humans cannot digest cellulose, but it nonetheless plays an important role in our diet. It acts as a water-attracting bulking agent for feces in the digestive tract and is often referred to as "dietary fiber."
::某些动物,包括白蚁和象奶牛这样的反胃动物,可以在其肠内生活的微生物的帮助下消化纤维素。 人类不能消化纤维素,但它在我们饮食中起着重要作用。 它作为消化道中粪便的一种吸引水的散装剂,常常被称为“食用纤维 ” 。Chitin
::基廷Chitin is a long-chain polymer of a derivative of glucose. It is found in many living things. For example, it is a component of the cell walls of fungi; the exoskeletons of , such as and (including the beetle pictured ); and the beaks and internal shells of animals, such as squids and octopuses. The structure of chitin is similar to that of cellulose.
::Chitin是葡萄糖衍生物的长链聚合物,存在于许多生物中,例如,它是真菌细胞墙的成分;是象和(包括所拍摄的甲虫)这样的外骨质;是象和(包括所拍摄的甲虫)的外骨质;是象鱿鱼和章鱼等动物的嘴和内壳。The tough outer skeleton (exoskelelton) of this ten-lined beetle is made partly of the complex carbohydrate chitin.
::这只十线甲虫的坚硬外壳(exokelton) 部分是由复杂的碳水化合物组成的。Feature: My Human Biology
::特写:我的人类生物学You probably know that you should eat plenty of fiber, but do you know how much fiber you need, how fiber contributes to good health, or which foods are good sources of fiber? Dietary fiber consists mainly of cellulose, so it is found primarily in plant-based foods, including fruits, vegetables, whole grains, and legumes. Dietary fiber can't be broken down and absorbed by your digestive system. Instead, it passes relatively unchanged through your gastrointestinal tract and is excreted in feces. That's how it helps keep you healthy.
::你可能知道,你应该吃很多纤维,但你知道你需要多少纤维,纤维如何促进健康,或者哪些食物是良好的纤维来源吗?饮食纤维主要由纤维素组成,因此它主要存在于植物食物中,包括水果、蔬菜、整粒谷物和豆类。饮食纤维不能通过消化系统分解和吸收。相反,它通过你的肠胃道相对没有变化,并且排泄在粪便中。这就是它如何帮助你保持健康。Fiber in food is commonly classified as either soluble or insoluble fiber.
::食物中的纤维通常被归类为可溶解或不可溶解的纤维。-
Soluble fiber
dissolves in
to form a gel-like substance as it passes through the gastrointestinal tract.
It l
owers blood levels of cholesterol and glucose, which is beneficial for your health. Good sources of soluble fiber include whole oats, peas, beans, and apples.
::溶解纤维溶解成凝胶类物质,随着它穿过胃肠道,会降低胆固醇和葡萄糖的血液水平,这对健康有益。 溶解纤维的良好来源包括整个燕麦、豆子、豆类和苹果。 -
Insoluble fiber
does not dissolve in water. This type of fiber increases the bulk of feces in the
, and helps keep food wastes moving through, which may help prevent or correct constipation. Good sources of insoluble fiber include whole wheat, wheat bran, beans, and potatoes.
::不可溶解的纤维不会在水中溶解。 这种纤维会增加大部分粪便,有助于保持食物废物的流通,从而帮助防止或纠正便秘。 不可溶解的纤维的良好来源包括整个小麦、小麦面包、豆类和土豆。
Beans are an excellent source of both soluble and insoluble fiber.
::豆类是可溶性和不可溶性纤维的极佳来源。How much fiber do you need for good health? That depends on your age and gender. The Institute of Medicine recommends the daily fiber intake for adults shown in the table . Most dietitians further recommend a ratio of about three parts of insoluble fiber to one part of soluble fiber each day. Most fiber-rich foods contain both types of fiber, so it usually isn't necessary to keep track of the two types of fiber as long as your overall fiber intake is adequate.
::健康需要多少纤维?这取决于你的年龄和性别。医学研究所推荐表格中显示的成年人每天的纤维摄入量。大多数饮食学家进一步建议,每天的纤维溶解率约为三分之一。大多数纤维丰富食品含有两种纤维,因此只要你的总体纤维摄入量充足,通常就没有必要跟踪这两种类型的纤维。Recommended Daily Fiber Intake for Males and Females Gender Age 50 or Younger Age 51 or Older Male 38 grams 30 grams Female 25 grams 21 grams Use food labels and online fiber counters to find out how much total fiber you eat in a typical day. Are you consuming enough fiber for good health? If not, consider ways to increase your intake of this important substance. For example, substitute whole grains for refined grains, eat more legumes (such as beans), and try to consume at least five servings of fruits and vegetables each day.
::使用食品标签和在线纤维反射器来找出您在典型的一天里所食用的纤维总量。 您是否为了健康而消费足够的纤维? 如果不是的话, 请考虑增加这种重要物质的摄入量的方法。 比如, 以整粒谷物替代精制谷物, 多吃豆子( 如豆子 ) , 并尝试每天至少消费五种水果和蔬菜。Summary
::摘要-
Carbohydrates are the most common class of biochemical compounds. The basic building block of carbohydrates is the monosaccharide, which consists of six carbon atoms.
::碳水化合物是最常见的生化化合物类别,碳水化合物的基本构件是单沙焦酸,由6个碳原子组成。 -
Sugars are sweet, short-chain, soluble carbohydrates that are found in many foods and supply us with energy. Simple sugars, such as glucose, consist of just one monosaccharide. Some sugars, such as sucrose (or table sugar), consist of two monosaccharides. These are called disaccharides.
::糖是甜的、短链的、可溶解的碳水化合物,它们存在于许多食品中,为我们提供能量。 简单的糖,如葡萄糖,只有一种单沙酸。 某些糖,如苏克罗斯(或食糖 ) , 由两种单沙酸组成。 这些叫做非沙酸。 -
Complex carbohydrates, or polysaccharides, consist of hundreds — or even thousands — of monosaccharides. They include starch, glycogen, cellulose, and chitin. They generally either store energy or form structures, such as cell walls, in living things.
::复合碳水化合物或聚碳酸盐由数百甚至数千个单碳酸盐组成,包括淀粉、甘醇、纤维素和辣椒,通常在生物物质中储存能量或形成结构,如细胞壁。 -
Starch is a complex carbohydrate that is made by plants to store energy. Potatoes are a good food source of dietary starch, which is readily broken down into its component sugars during digestion.
::淀粉是一种复杂的碳水化合物,由植物制成,用于储存能量。 土豆是饮食淀粉的良好食物来源,在消化过程中很容易分解成其成分糖。 -
Glycogen is a complex carbohydrate that is made by animals and fungi to store energy. Glycogen plays a critical part in the homeostasis of blood glucose levels in humans.
::甘油是一种复杂的碳水化合物,由动物和真菌制成,以储存能量。 甘油在人类血液甘蔗糖水平的均匀状态中起着关键作用。 -
Cellulose is the single most common biochemical compound in living things. It forms the cell walls of plants and certain algae. Like most other animals, humans cannot digest cellulose, but it makes up most of the crucial dietary fiber in the human diet.
::纤维素是生命中最常见的单一生化化合物。 它构成植物和某些藻类的细胞壁。 与其他动物一样,人类不能消化纤维素,但它构成人类饮食中最重要的饮食纤维。 -
Chitin is a complex carbohydrate, similar to cellulose, that makes up organic structures, such as the cell walls of fungi and the exoskeletons of insects and other arthropods.
::Chitin是一种复杂的碳水化合物,类似于纤维素,构成有机结构,如真菌的细胞壁和昆虫和其他节肢动物的外骨质素。
Review
::回顾1. What are carbohydrates? Describe their structure.
::1. 什么是碳水化合物?描述其结构。2. Compare and contrast sugars and complex carbohydrates.
::2. 比较和对比糖和复杂的碳水化合物。3. Identify the four main types of complex carbohydrates and their functions.
::3. 查明四种主要类型的复杂碳水化合物及其功能。4. If you chew on a starchy food (such as a saltine cracker) for several minutes, it may start to taste sweet. Explain why.
::4. 如果你嚼了几分钟的沙粒食物(如盐饼干),可能会开始尝到甜食,解释原因。5. True or False: Glucose is mainly stored by lipids in the human body.
::5. 真实或假:甘蔗主要由人体脂肪储存。6. Put the following carbohydrates in order from smallest to largest:
::6. 将下列碳水化合物从最小改为最大:cellulose; fructose; sucrose
::纤维素; 纤维素; 纤维素; 纤维素7. Name three carbohydrates that contain glucose as a monomer.
::7. 列出三种含葡萄糖的碳水化合物作为单体。8. Jeans are made of tough, durable cotton. B ased on what you know about the structure of carbohydrates, e xplain how you think this fabric gets its tough qualities.
::8. Jeans是由坚硬、耐久的棉花制成的,根据你对碳水化合物结构的了解,解释一下你认为这种织物是如何获得其难用品质的。9. Which do you think is faster to digest — simple sugars or complex carbohydrates? Explain your answer.
::9. 你认为哪一种能更快地消化——简单的糖或复杂的碳水化合物?解释你的答复。10. True or False: Cellulose is broken down in the human digestive system into glucose molecules.
::10. 真实或假:纤维素在人类消化系统中分解成葡萄糖分子。11. ___________ fiber dissolves in water, __________ fiber does not dissolve in water.
::11. 纤维溶于水, 纤维不溶于水。12. What are the similarities and differences between muscle glycogen and liver glycogen?
::12. 肌肉甘基和肝甘基之间有什么相似之处和区别?13. Which carbohydrate is used directly by the cells of living things for energy?
::13. 哪些碳水化合物直接用于生物细胞的能源?14. Which of the following is not a complex carbohydrate?
::14. 以下哪一种不是复杂的碳水化合物?a. chitin
::a.b. starch
::b. 淀粉c. disaccharide
::c. 失利d. none of the above
::d. 以上无任何内容Explore More
::探索更多Watch the video below to learn about the health impacts of carbohydrates.
::了解碳水化合物对健康的影响。In the TED Talk below, Suzanne Lee discusses growing fabric out of cellulose.
::在下文TED演讲中, Suzanne Lee讨论用纤维素种植纤维。 -
Soluble fiber
dissolves in
to form a gel-like substance as it passes through the gastrointestinal tract.
It l
owers blood levels of cholesterol and glucose, which is beneficial for your health. Good sources of soluble fiber include whole oats, peas, beans, and apples.
