DNA is the complex chemical that carries genetic information. DNA is contained in chromosomes, which are found in the nucleus of most cells.The gene is the unit of inheritance and different forms of the same gene are called alleles.Cystic fibrosis is an inherited disorder caused by a faulty allele.hey consist of long strands of a substance called deoxyribonucleic acid, or DNA for short. A section of DNA that has the genetic code for making a particular protein is called a gene. The gene is the unit of inheritance, and each chromosome may have several thousand genes.