Crucigrama Basic Genetics IVersión en línea Quiz of day 1 genetics vocabulary. por Dr. Cross 1 a nucleic acid present in all living cells. Its principal role is to act as a messenger carrying instructions from DNA 2 a self-replicating material that is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information. 3 organelle that protects chromosomes (DNA) 4 different versions of a gene 5 fundamental units of heredity 6 large DNA molecules encode many genes 1 2 5