Reading Chapters In The Genome
Every cell in the body stems from just one cell: the fertilized egg.
Every cell contains the same library of instructions, but the cells read and use different genetic chapters.
Reading Chapters from the Genome
Every cell in the body contains all of the DNA sequence, but the composition of each cell depends on which sections of the DNA are used. We know that each cell reads only those chapters from the library of instructions that it needs. The selective reading process creates many different kinds of cells, such as skin, muscle, neural, and bone cells, all of which develop from the many cells of the embryo produced by the growth and division of one cell: the fertilized egg. Studies of the fruit fly, Drosophila melanogaster, have been useful in revealing how organisms develop these cell types, with each cell knowing what chapters to read according to its position in the developing embryo.
The human body has between 50 and 100 trillion cells and no single cell is in charge. Throughout a lifetime, each cell interacts with many other cells to determine which instructions to use at a particular time and place.