The World of Genetics: Life Science (Science Readers)

To understand why humans are the way they are, look at cells and the special material in their center called chromosomes. People have 23 pairs of chromosomes, so each cell has 46 in all. Parents pass chromosomes to their children. DNA carries the genetic information in alleles and is the blueprint for the cells of an organism. It also tells one's body how to put certain materials together to produce certain traits.