16 - The Molecular Basis of Inheritance Ch. 16: The Molecular Basis of Inheritance Concept 16.1: DNA is the genetic material Early in the 20th century, the identification of the molecules of inheritance loomed as a major challenge to biologists When T. H. Morgan?s group showed that genes are located on chromosomes, the two components of chromosomes?DNA and protein?became candidates for the genetic material A chromosome consists of a DNA molecule packed together with proteins The bacterial chromosome is a double-stranded, circular DNA molecule associated with a small amount of protein Eukaryotic chromosomes have linear DNA molecules associated with a large amount of protein In a bacterium, the DNA is ?supercoiled? and found in a region of the cell called the nucleoid