Cell
细胞
Every living thing has at least one cell.
每个生物至少有一个细胞。
Then, what is a cell?
那么,什么是细胞呢?
Every cell works differently, but most cells work to maintain life.
每个细胞的功能都不相同,但大多数的细胞都有维持生命的作用。
Therefore, a cell is often called the building block of life.
因此,细胞常被称作是构成生命的基本单元。
A small house needs a small number of bricks, a big house needs many bricks.
小房子需要少量的砖块,大房子则需要很多砖块。
Similarly, small organisms need only a few cells.
同样,小型生物仅需要几个细胞。
For example, most bacteria have only one cell.
例如,大多数细菌仅有一个细胞。
But big organisms like animals or plants need a lot of cells.
而像动植物这样的大型生物则需要大量的细胞。
How many cells do people have?
人有多少个细胞呢?
They have about 100 trillion cells!
人约有100万亿个细胞!