According to one of these articles : In the purest forms of the concepts , units of genetically functional DNA might be viewed as `` replicating entities '' that effect their replication by manipulating the physiological activities of the cell that they control ; in contrast , units of selfish DNA affect their replication by exploiting existing DNA and DNA-manipulating mechanisms in the cell , notionally without significantly affecting the fitness of the organism in other respects .
Normal genetically functional DNA might be seen as `` replicating entities '' that effect their replication by manipulating the cell that they control . In contrast , units of selfish DNA may exploit existing mechanisms in the cell , and multiply without affecting the fitness of the organism in other respects .