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    Understanding chemistry is essential to fully understand biology. Why?
    ::理解化学是完全理解生物学的关键。为什么?

    A general understanding of chemistry is necessary to understand biology . Essentially, our are just thousands of chemicals — made of elements like carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur — in just the right combinations. And these chemicals combine through chemical reactions .
    ::对化学的普遍理解对于理解生物学是必要的。 从根本上说,我们只有数千种化学物质 — — 由碳、氢、氧、氮、磷和硫等元素组成 — — 以正确的组合组成。 这些化学物质通过化学反应结合在一起。

    What Are Chemical Reactions?
    ::什么是化学反应?

    A chemical compound may be very different from the substances that combine to form it. For example, the element chlorine (Cl) is a poisonous gas, but when it combines with sodium (Na) to form sodium chloride (NaCl), it is no longer toxic. You may even eat it on your food . Sodium chloride is just table salt. What process changes a toxic chemical like chlorine into a much different substance like table salt?
    ::例如,元素氯(Cl)是一种有毒气体,但当它与钠(Na)结合形成氯化钠(NaCl)时,它就不再有毒了。你甚至可以在食物上吃它。氯化钠只是桌盐。什么过程将氯这样的有毒化学物质改变成完全不同的物质,比如盐?

    A chemical reaction is a process that changes some chemical substances into other chemical substances. The substances that start a chemical reaction are called reactants . The substances that form as a result of a chemical reaction are called products . During the reaction, the reactants are used up to create the products. For example, when methane burns in oxygen, it releases carbon dioxide and . In this reaction, the reactants are methane (CH 4 ) and oxygen (O 2 ), and the products are carbon dioxide (CO 2 ) and water (H 2 O).
    ::化学反应是一种将某些化学物质改变为其他化学物质的过程。开始化学反应的物质称为反应剂。由于化学反应而形成的物质称为产品。在反应过程中,反应剂被用来制造产品。例如,当氧气中甲烷燃烧时,它释放二氧化碳和二氧化碳。在这种反应中,反应剂是甲烷(CH4)和氧(O2),产品是二氧化碳(CO2)和水(H2O)。

    Chemical Equations
    ::化学等量

    A chemical reaction can be represented by a chemical equation . Using the same example, the burning of methane gas can be represented by the equation:
    ::化学反应可以用化学方程式表示。用同一例子,甲烷气体的燃烧可以用公式表示:

    CH 4 + 2 O 2 → CO 2 + 2 H 2 O.
    ::CH4 + 2 O2 + CO2 + 2 H2O。

    The arrow in a chemical equation separates the reactants from the products and shows the direction in which the reaction occurs. If the reaction could also occur in the opposite direction, then two arrows, one pointing in each direction, or one arrow pointing in both directions, would be used. On each side of the arrow, a mixture of chemicals is indicated by the chemical symbols joined by a plus sign (+). The numbers preceding some of the chemical symbols (such as 2 O 2 ) indicate how many molecules of the chemicals are involved in the reaction. (If there is no number in front of a chemical symbol, it means that just one molecule is involved.)
    ::化学方程式中的箭头将反应器与产品分开,并显示反应发生的方向。如果反应也可能发生在相反的方向上,那么将使用两支箭头,一个指向每个方向,或一个指向两个方向的箭头。在箭头的两侧,化学符号加一个符号(+)以化学符号表示一种化学混合物。一些化学符号(如2O2)前面的数字表示该反应涉及多少个化学分子。 (如果化学符号前面没有数字,这意味着只涉及一个分子。 )

    In a chemical reaction, the quantity of each element does not change. There is the same amount of each element at the end of the reaction as there was at the beginning. This is reflected in the chemical equation for the reaction. The equation should be balanced. In a balanced equation, the same number of atoms of a given element appear on each side of the arrow. For example, in the equation above, there are four hydrogen atoms on each side of the arrow.
    ::在化学反应中,每个元素的数量不会改变。 反应结尾处每个元素的数量与开始时相同。 这反映在反应的化学方程式中。 方程式应该平衡。 在平衡方程式中, 箭头两侧都有相同数量的元素原子。 例如, 在以上方程式中, 箭头两侧都有四个氢原子 。

    Types of Chemical Reactions
    ::化学反应类型

    In general, a chemical reaction involves the breaking and forming of chemical bonds . In the methane reaction above, bonds are broken in methane and oxygen, and bonds are formed in carbon dioxide and water. A reaction like this, in which a compound or element burns in oxygen, is called a combustion reaction . This is just one of many possible types of chemical reactions. Other types of chemical reactions include synthesis, decomposition, and substitution reactions.
    ::一般而言,化学反应涉及化学结层的破碎和形成,在上文的甲烷反应中,甲烷和氧层断裂,二氧化碳和水层断裂,二氧化碳和水层断裂。类似反应中,氧化合物或元素燃烧被称为燃烧反应。这只是多种可能的化学反应之一。其他类型的化学反应包括合成、分解和替代反应。

    • A synthesis reaction occurs when two or more chemical elements or compounds unite to form a more complex product. For example, nitrogen (N 2 ) and hydrogen (H 2 ) unite to form ammonia (NH 3 ):
      ::当两个或两个以上化学元素或化合物合在一起形成一个更复杂的产品时,即发生合成反应。

    N 2 + 3 H 2 → 2 NH 3 .
    ::N2 + 3 H2 + 2 NH3。

    • A decomposition reaction occurs when a compound is broken down into smaller compounds or elements. For example, water (H 2 O) breaks down into hydrogen (H 2 ) and oxygen (O 2 ):
      ::当化合物分解成较小的化合物或元素时,就会发生分解反应。例如,水(H2O)分解成氢(H2)和氧(O2):

    2 H 2 O → 2 H 2 + O 2 .
    ::2 H2O 2 H2 + O2。

    • A substitution reaction occurs when one element replaces another element in a compound. For example, sodium (Na + ) replaces hydrogen (H) in hydrochloric acid (HCl), producing sodium chloride (NaCl) and hydrogen gas (H 2 ):
      ::当一个元素取代一个化合物中的另一个元素时,就会发生替代反应。例如,钠(Na+)取代盐酸(HCl)中的氢(H),生产氯化钠(NACl)和氢气(H2):

    2 Na + + 2 HCl → 2 NaCl + H 2 .
    ::2 Na+ + 2 HCl 2 NaCl + H2。

    Redox Reactions
    ::Rex 红色反应

    Reduction-oxidation reactions, or redox reactions include all chemical reactions in which atoms have their oxidation state changed. This can be either a simple redox process, such as the oxidation of carbon into carbon dioxide or the reduction of carbon by hydrogen into methane, or a complex process such as the oxidation of glucose through a series of complex electron transfer processes during . Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion . Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.
    ::减少氧化反应或红氧化反应包括原子的氧化状态发生变化的所有化学反应。这可以是简单的氧化过程,如碳氧化成为二氧化碳或氢减少碳成为甲烷,也可以是复杂的过程,如在.期间通过一系列复杂的电子转移过程氧化葡萄糖。氧化是指电子的丧失或分子、原子或离子的氧化状态的增加。减少是指电子的增益或分子、原子或离子的氧化状态的减少。减少是指电子的增益或分子、原子或离子的氧化状态的减少。

    Redox Reactions in Biology
    ::生物学中的红色反应

    Many important biological processes involve redox reactions, which frequently store and release energy . For example, involves the reduction of carbon dioxide into glucose and the oxidation of water into oxygen. This process stores the energy of sunlight in the bonds of sugars. The reverse reaction, cellular respiration, converts the energy in glucose into ATP . Cellular respiration involves the oxidation of glucose to carbon dioxide and the reduction of oxygen gas to water. This process depends on the reduction of NAD + to the electron carrier NADH , and the reverse oxidation of NADH to NAD + . The reduction of NAD + leads to the formation of a proton (H + ) gradient, which drives the synthesis of ATP. NADH (nicotinamide adenine dinucleotide) and NADPH (Nicotinamide adenine dinucleotide phosphate) are electron carriers in biological systems. The term redox state is often used to describe the balance between NAD + /NADH and NADP + /NADPH (Nicotinamide adenine dinucleotide phosphate).
    ::许多重要的生物过程涉及红氧化反应,经常储存和释放能量,例如,将二氧化碳减到葡萄糖中,将水氧化到氧中,这一过程将阳光的能量储存在糖的粘结中。反反应、细胞呼吸、将葡萄糖中的能量转换成ATP。细胞呼吸涉及将葡萄糖氧化为二氧化碳和将氧气减少到水中。这一过程取决于将NAD+减到电子载体NADH,以及将NADH反氧化到NADH+。NADDH的减少导致形成质子(H+)梯度,驱动ATP合成。NADH(Nicodinaminide adenine dinucleotide)和NADPH(Nicotinamid adine den dinucleotide 磷酸盐)是生物系统中的电载体。红色状态通常用来描述NAD+/NADDH+/NADP+/NADPH(NADPH)之间的平衡。

     

     

    Summary
    ::摘要

    • A chemical reaction is a process that changes some chemical substances into others. It involves breaking and forming chemical bonds.
      ::化学反应是一种将某些化学物质改变为其他化学物质的过程,它涉及打破和形成化学联结。
    • Types of chemical reactions include synthesis reactions and decomposition reactions.
      ::化学反应的类型包括合成反应和分解反应。

    Review
    ::回顾

    1. Identify the roles of reactants and products in a chemical reaction.
      ::确定反应物和产品在化学反应中的作用。
    2. Describe each type of chemical reaction.
      ::描述每一种化学反应。
    3. What is wrong with the following chemical equation? How could you fix it? CH 4 + O 2 → CO 2 + 2H 2 O
      ::以下化学方程式有什么问题? 您如何修补 CH4 + O2 + CO2 + 2H2O ? CH4 + o2 + CO2 + 2H2O
    4. What type of reaction is represented by the following chemical equation? Explain your answer. 2Na + 2HCl → 2NaCl + H 2
      ::以下化学方程式代表何种反应? 请解释您的答复。 2Na + 2HCl + 2NaCl + H2