We all start life as one single cell. Then that cell divides and we are two cells, then four, then eight. Cells form tissues, tissues form organs, organs form us. These cell divisions, by which we go from a single cell to 100 trillion cells, are called growth. trillion - 1兆 And growth seems like a simple thing because when we think of it, we typically think of someone getting taller or, later in life, wider, but to cells, growth isn't simple. Cell division is an intricate chemical dance that's part individual, part community-driven. intricate [íntrikət ] - 入り組んだ、複雑な And in a neighborhood of 100 trillion cells, some times things go wrong. Maybe an individual cell's set of instructions, or DNA, gets a typo, what we call a mutation . mutation - 突然変異 Most of the time, the cell senses mistakes and shuts itself down, or the system detects a troublemaker and eliminates it. But, enough mutations can bypass the fail-safes , driving the cell to divide reck...
