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    Carbon. Element number six. Right in the middle of the first row of the Periodic Table. So what?
    ::碳元素六,在周期表第一排中间,那又怎样?

    Carbon is the most important element to life. Without this element, life as we know it would not exist. As you will see, carbon is the central element in compounds necessary for life- . These compounds include , , and .
    ::碳是生命中最重要的元素。没有这个元素,我们知道生命是不存在的。正如你将看到的那样,碳是生命中必需的化合物中的核心元素。这些化合物包括 , 和 。

    The Significance of Carbon
    ::碳的重要性

    Why is carbon so important to organisms ? The answer lies with carbon’s unique properties. Carbon has an exceptional ability to bind with a wide variety of other elements. Carbon makes four electrons available to form covalent chemical bonds , allowing carbon atoms to form multiple stable bonds with other small atoms, including hydrogen, oxygen, and nitrogen. Carbon atoms can also form stable bonds with other carbon atoms. In fact, a carbon atom may form single, double, or even triple bonds with other carbon atoms. This allows carbon atoms to form a tremendous variety of very large and complex molecules.
    ::碳为什么对生物如此重要? 答案在于碳的独特特性。 碳具有与多种其他元素结合的特殊能力。 碳提供四种电子以形成共价化学债券,允许碳原子与其他小原子(包括氢、氧和氮)形成多重稳定联系。 碳原子也可以与其他碳原子形成稳定联系。 事实上,碳原子可能形成单一的、双倍的甚至三倍的碳原子与其他碳原子的结合。 这让碳原子形成巨大而复杂的分子。

    Organic Compounds
    ::有机化合物

    Carbon has the ability to form very long chains of interconnecting C-C bonds. This property allows carbon to form the backbone of organic compounds , carbon-containing compounds, which are the basis of all known organic life. Nearly 10 million carbon-containing organic compounds are known. Types of carbon compounds in organisms include carbohydrates, lipids, proteins, and nucleic acids. The elements found in each type are listed in the table below. Elements other than carbon and hydrogen usually occur within organic compounds in smaller groups of elements called functional groups . When organic compounds react with other compounds, generally just the functional groups are involved. Therefore, functional groups generally determine the nature and functions of organic compounds.
    ::碳有能力形成连接C-C债券的长链。这种特性使碳成为所有已知有机生命基础的有机化合物、含碳化合物的骨干。已知含碳有机化合物将近1 000万种。有机体中的碳化合物类型包括碳水化合物、脂类、蛋白质和核酸。在以下表格中列出了每种类型的元素。在有机化合物中,碳和氢以外的元素通常出现在称为功能组的较小类别有机化合物中。当有机化合物与其他化合物发生反应时,通常只涉及功能组。因此,功能组通常决定有机化合物的性质和功能。

    When combined with oxygen and hydrogen, carbon can form many groups of important biological compounds including carbohydrates (sugars), lignans (important in plants), chitins (the main component of the cell walls of , the exoskeletons of arthropods), alcohols, lipids and fats (triglycerides), and carotenoids (plant pigment). With nitrogen it forms alkaloids, and with the addition of sulfur in addition to the nitrogen, it forms amino acids which bind together to form proteins , antibiotics , and rubber products. With the addition of phosphorus to these other elements, carbon forms nucleotides which bond into nucleic acids ( and RNA), and adenosine triphosphate (ATP) , which is known as the energy currency of the . The properties of all these organic molecules is related to the composition of the elements that compose the molecule. Certain carbohydrates, proteins and nucleic acids are known as macromolecules, as they are very large polymers made of individual monomers .
    ::当碳与氧和氢相结合时,碳可以形成许多组重要的生物化合物,包括碳水化合物(糖)、乳液(在植物中很重要)、酸(细胞壁的主要组成部分,节肢动物的外壳)、酒精、脂类和脂肪(硫酸盐)和碳质素(植物色素),碳可以形成许多组重要的生物化合物,它与氮形成藻类,加上硫磺,形成氨酸,结合形成蛋白质、抗生素和橡胶制品。随着磷的加入,碳形式的核酸(核酸的外壳和RNA),碳形式的核酸(核酸的结合物)和亚甲酸三磷酸(ATP),称为核酸的能量货币。所有这些有机分子的特性与分子构成要素的构成有关。某些碳水化合物、蛋白质和核酸被称作大型单体聚合物,它们都是由单体制成的大型聚合物。

      

     

    A Comparison
    ::A. 比较比较

    Type of Compound Elements It Contains Examples Functions
    Carbohydrates carbon, hydrogen, oxygen Glucose , Starch , Glycogen provides energy to cells, stores energy, forms body structures
    Lipids carbon, hydrogen, oxygen Cholesterol, Triglycerides (fats), Phospholipids stores energy, forms , carries messages
    Proteins carbon, hydrogen, oxygen, nitrogen, sulfur , Antibodies helps cells keep their shape/structure, makes up , catalyzes chemical reactions , carries messages and materials
    Nucleic Acids carbon, hydrogen, oxygen, nitrogen, phosphorus Deoxyribonucleic acid (DNA), Ribonucleic acid (RNA), Adenosine Triphosphate (ATP) contains instructions for proteins, passes instructions from parents to offspring, helps make proteins

    The Table lists the four types of organic compounds, the elements they contain, and examples and functions of each type of compound.
    ::表格列出了四种类型的有机化合物、其中所含的成分以及每种化合物的示例和功能。

    Condensation and Hydrolysis
    ::凝聚和水解

    Condensation reactions are the chemical processes by which large organic compounds are synthesized from their monomeric units. Hydrolysis reactions are the reverse process. During condensation reactions, is produced from the two molecules being bonded together; an H from one monomer is joined to an -OH from another molecule, producing H 2 O.
    ::浓缩反应是化学过程,通过这种过程,从它们的单体单元中合成大型有机化合物。水解反应是反向过程。在凝聚反应期间,由两个分子结合而产生;一个单体的H与另一个分子的-OH结合,产生H2O。

    Polymer Monomer Bond
    carbohydrates monosaccharides glycosidic
    lipids fatty acid ester*
    proteins amino acids peptide
    nucleic acids nucleotides phosphodiester**
    • The ester linkage is between a glycerol molecule and fatty acid chain.
      ::酯间的联系是甘油分子和脂肪酸链之间的联系。

    Summary
    ::摘要

    • Carbon’s exceptional ability to form bonds with other elements and with itself allows it to form a huge number of large, complex molecules called organic molecules. These molecules make up organisms and carry out life processes.
      ::碳与其他元素形成联系的超常能力,以及它自身形成大量称为有机分子的大型复杂分子的能力。 这些分子组成有机体并进行生命过程。

    Review
    ::回顾

    1. Why is carbon essential to all known life on Earth?
      ::为什么碳对于地球上所有已知生命至关重要?
    2. What is an organic compound? Give an example.
      ::有机化合物是什么?
    3. List the four main classes of organic compounds. What are examples of each?
      ::列出有机化合物的四大类。 每种有机化合物的示例是什么 ?
    4. What is condensation? What is hydrolysis?
      ::什么是凝结?什么是水解?
    5. What is a phosphodiester bond?
      ::什么是磷磷联结?