As the catalytic component of the DNA polymerase gamma complex is involved in the replication of mitochondrial DNA (mtDNA) (PubMed:3095323, PubMed:7499423, PubMed:8798543, PubMed:11917141, PubMed:19924234, PubMed:15537632, PubMed:28430993). Has both 5'-3' DNA polymerase and a highly mispair-specific 3'-5' exonuclease activity (PubMed:2671990, PubMed:7499423, PubMed:8798543, PubMed:28430993, PubMed:26554610, PubMed:15537632). At the end of mtDNA replication DNA ends are ligated to produce a closed circular mtDNA molecule, its exonuclease activity is required for formation of these ligatable ends by preventing DNA synthesis from continuing past the 5'-end of downstream DNA into duplex DNA regions (PubMed:28430993). Does not possess DNA primase activity, does not catalyze strand displacement synthesis and does not contain a 5'-3' exonuclease activity to catalyze nick translation (PubMed:3095323). Important for promoting the elimination of paternal mitochondrial DNA during spermatogenesis, however its exact role in this function has not yet been identified and appears to be independent of its 3'-5'-exonuclease activity and only partially dependent on its DNA polymerase activity (PubMed:28318978). a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Stimulated by KCl, and inhibited by the small molecules o 2',3'-dideoxythymidine 5'-triphosphate (d2TTP) and N-ethylmaleimide (NEM). Optimum pH is 9.0. Component of the DNA polymerase gamma complex consisting of two subunits: the catalytic subunit DNApol-gamma/DNApolG1 and the accessory subunit PolG2/DNApol-gamma35. In sperm, detected in puncta that associate with mitochondrial nucleoids at developmental stages when the nucleoids are being eliminated. Expressed in the embryo (at protein levels) (PubMed:3095323). Expressed at high levels in eggs and to a lesser extent during embryonic development (PubMed:10930405). Expressed at all larval stages and at higher levels in adults (PubMed:10930405). Larval lethal due to severe defects in mitochondrial DNA (mtDNA) replication and synthesis (PubMed:26554610). Larvae display a severe decrease in body weight and a 70% decrease in mtDNA levels but are able to survive on maternal contribution until the third larval stage (PubMed:26554610). RNAi-mediated knockdown in male germline cells, results in defective clearance of paternal mitochondrial nucleoids (containing mitochondrial DNA) during spermatogenesis (PubMed:28318978). Eggs fertilized by mutant males do not display an increase in male mtDNA levels, suggesting that it does not affect regulatory pathways in the embryo that prevent the paternal transmission of mtDNA (PubMed:28318978). Belongs to the DNA polymerase type-A family.