Skip to main content
. 2014 Sep 30;9(9):e106654. doi: 10.1371/journal.pone.0106654

Figure 1. Models of mtDNA replication in vertebrates.

Figure 1

Heavy-strand and Light-strand represented in black and grey, respectively. (SDM) In the strand-displacement model, replication of the H-strand initiates at OriH and is synthesized unidirectionally (black arrow), displacing the parental H-strand as single-stranded DNA. When OriL (or OriLalt) is exposed, the L-strand synthesis initiates in the opposite direction (grey arrow). (RITOLS) In the Ribonucleotide incorporation throughout the lagging strand model, synthesis of the H-strand initiates at a discrete origin (OriH) and proceeds unidirectionally (black arrow), displacing the parental H-strand. The L-strand is initially laid down as RNA (grey dashed line) using the displaced H-strand as template. The RNA is subsequently replaced with DNA (gray arrow). The maturation step usually starts at the OriL. (SCM) In the strand-coupled model, initiation of both H-strand and L-strand synthesis occurs bidirectionally from multiple origins across a broad zone downstream of OriH. This is followed by progression of both forks until the forks arrest at OriH. Black or grey dashed lines represent newly synthesized DNA Okazaki fragments.