Читать книгу Infants and Children in Context - Tara L. Kuther - Страница 91

The human body is composed of trillions of units called cells, each with a nucleus containing 23 matching pairs of rod-shaped structures called chromosomes (Plomin, DeFries, Knopik, & Neiderhiser, 2013). Each chromosome holds the basic units of heredity, known as genes, composed of stretches of deoxyribonucleic acid (DNA), a complex molecule shaped like a twisted ladder or staircase. Genes carry the plan for creating all of the traits that organisms carry. It is estimated that 20,000 to 25,000 genes reside within the chromosomes, comprising the human genome and influencing all genetic characteristics (Finegold, 2017).

Much of our genetic material is not unique to humans. Every species has a different genome, yet we share genes with all organisms, from bacteria to primates. We share 99% of our DNA with our closest genetic relative, the chimpanzee. There is even less genetic variation among humans. People around the world share 99.7% of their genes (Lewis, 2017). Although all humans share the same basic genome, every person has a slightly different code, making him or her genetically distinct from other humans.