The Molecules of Life
The elements involved in life processes can, and do, form millions ofdifferent compounds. Thankfully, these millions of compounds fall intofour major groups: carbohydrates, proteins, lipids, and nucleic acids.Though all of these groups are organized around carbon, each group hasits own special structure and function.分子的生活
生命过程所涉及的元素可以形成数百万种不同化合物。这些化合物有：碳水化合物，蛋白质，脂类，核酸.所有这些周围都是由碳的结构组成，每组hasits？拥有特殊的结构和功能。
Carbohydrates
Carbohydrates are compounds that havecarbon, hydrogen, and oxygen atoms in a ratio of about 1:2:1. If you’restuck on an SAT II Biology question about whether a compound is acarbohydrate, just count up the atoms and see if they fit this ratio.Carbohydrates are often sugars, which provide energy for cellularprocesses.
Like all of the biologically importantclasses of compounds, carbohydrates can be monomers, dimers, orpolymers. The names of most carbohydrates end in “-ose”: glucose, fructose, sucrose, and maltose are some common examples. 碳水化合物
碳水化合物是含碳 ，氢，氧原子构成，比例约为1：2：1。如果在SAT2生物学考试中，关于是否是一种复水碳水化合物的问题，那么就数一下原子和看看他们是否适合这个比。碳水化合物往往是提供能源给细胞的过程的糖类 。
像所有的生物重要化合物的种类如：碳水化合物，单体，二聚体， 或者聚合体 。大部分碳水化合物名字的后面有“-OSE” ：葡萄糖，果糖，蔗糖，麦芽糖是一些常见的例子。
Monosaccharides
Carbohydrate monomers are known as monosaccharides. This group includes glucose, C6H12O6,which is a key substance in biochemistry. Sugars that an animal eatsare converted into glucose, which is then converted into energy to fuelthe animal’s activities by respiration (see Cell Processes).
Glucose has a cousin called fructose with the same chemical formula. But these two compounds have different structures:
Glucose and fructose differ in one importantway: glucose has a double-bonded oxygen on the top carbon, whilefructose has its double-bonded carbon on the second carbon. Thisdifference is most apparent when the two monosaccharides are in theirring forms. Glucose generally forms a hexagonal ring (six sided), whilefructose forms a pentagonal ring (five sided). Whereas fructose is thesugar most often found in fruits, glucose is most often used as themajor source of energy for cellular activities.
葡萄糖与果糖具有相同的化学分子式（C6H1206)但是这两个化合物具有不同的结构(我没记错的话是一个有醛基，一个没有）
在一个重要的方面葡萄糖和果糖不同：葡萄糖有一个双键对顶端的碳，而果糖的双键碳在第二个碳上。当两个单糖是在其环的形式这种差异是最明显的。葡萄糖一般形成了一个六角环（ 6片面） ，而果糖形成了一个五角环（ 5片面） 。在水果中的经常发下的糖是果糖，葡萄糖是作为主要的能源来源，为细胞活动提供能量。