The cell has been compared to many things, from "a complex chemical refinery" (by the physicist James Trefil) to "a vast, teeming metropolis" (the biochemist Guy Brown). A cell is both of those things and neither. It is like a refinery in that it is devoted to chemical activity on a grand scale, and like a metropolis in that it is crowded and busy and filled with interactions that seem confused and random but clearly have some system to them. But it is a much more nightmarish place than any city or factory that you have ever seen. To begin with there is no up or down inside the cell (gravity doesn't meaningfully apply at the cellular scale), and not an atom's width of space is unused. There is activity every where and a ceaseless thrum of electrical energy. You may not feel terribly electrical, but you are. The food we eat and the oxygen we breathe are combined in the cells into electricity. The reason we don't give each other massive shocks or scorch the sofa when we sit is that it is all happening on a tiny scale: a mere 0.1 volts traveling distances measured in nanometers. However, scale that up and it would translate as a jolt of twenty million volts per meter, about the same as the charge carried by the main body of a thunderstorm.
细胞被许多人比喻成许多事物，从“一个复杂的化学精炼厂（物理学家詹姆斯·特菲尔）”到“一个人口稠密的大都市”（生物学家盖伊·布朗）。细胞既是二者而又都不是。说它像个精炼厂，是因为在其内部进行着规模巨大的化学活动；说它像个大都市，是因为里面拥挤不堪，忙忙碌碌，充满互动，貌似纷繁混乱，却有着自成一体的结构。不过，它实质上比你所见过的庄何城市或工厂都要可怕得多。首先，在细胞内部没有上下之分（引力对细胞大小的东西几乎不起任何作用），它的每一处原子大小的空间都被充分地利用。活动到处存在，电流不停流动。你也许并不觉得自己带很多电，实际上是带的。我们吃的东西、呼吸的氧气在细胞里被合成电流。那么。我们为什么在相互接触时没有把对方击倒，或者我们坐在沙发上时又为什么没有将沙发烧焦呢？原因在于这一切都是在非常小的规模内发生的：电压仅仅是0.1伏，传输的距离要以纳米来计算。然而，如果将其按比例扩大，它所产生的冲击力相当于每平方米2000万伏，与一次雷电核心区所产生的电荷一样多。

Whatever their size or shape, nearly all your cells are built to fundamentally the same plan: they have an outer casing or membrane, a nucleus wherein resides the necessary genetic information to keep you going, and a busy space between the two called the cytoplasm.
不论其形状和大小如何，你身上所有细胞的构造大体相同：它们都有一层外壳或细胞膜。一个细胞核，里面存储着你正常运转所必需的基因信息。两者之间有一层繁忙的空间，叫做细胞质。