1. a displacement loop formed early in the replication of duplex DNA (either circular or linear) consisting of a single, unreplicated, parental strand on one side, and a double-stranded branch (composed of one parental strand paired with the leading strand, q.v.) on the other side. Because the leading strand displaces the unreplicated parental strand, the replication “bubble” or “eye” is called a displacement or D loop. 2. a region of vertebrate mtDNA that is noncoding but contains promoters and an origin for the replication of mtDNA. Shortly after replication is initiated, a temporary arrest in DNA elongation creates this displacement loop. The D loop is a bubble in which one strand of the control region has been copied and the other displaced. This D loop has been used as a target region for sequence comparisons when erecting phylogenetic trees. See Neandertal.
Subjects: Genetics and Genomics — Chemistry.