The processes that establish the spatial arrangement of mitochondria within the cell.

In base excision repair, an altered base is removed by a DNA glycosylase enzyme, followed by excision of the resulting sugar phosphate. The small gap left in the DNA helix is filled in by the sequential action of DNA polymerase and DNA ligase.

The formation of an AP site, a deoxyribose sugar with a missing base, by DNA glycosylase which recognizes an altered base in DNA and catalyzes its hydrolytic removal. This sugar phosphate is the substrate recognized by the AP endonuclease, which cuts the DNA phosphodiester backbone at the 5' side of the altered site.

Repair of the damaged strand by the combined action of an apurinic endouclease that degrades a few bases on the damaged strand and a polymerase that synthesizes a 'patch' in the 5' to 3' direction, using the undamaged strand as a template.

The ligation by DNA ligase of DNA strands. Ligation occurs after polymerase action to fill the gap left by the action of endonucleases during base-excision repair.

In nucleotide excision repair a small region of the strand surrounding the damage is removed from the DNA helix as an oligonucleotide. The small gap left in the DNA helix is filled in by the sequential action of DNA polymerase and DNA ligase. Nucleotide excision repair recognizes a wide range of substrates, including damage caused by UV irradiation (pyrimidine dimers and 6-4 photoproducts) and chemicals (intrastrand cross-links and bulky adducts).

The process whose specific outcome is the progression of the axial mesoderm over time, from its formation to the mature structure. The axial mesoderm includes the prechordal mesoderm and the chordamesoderm. It gives rise to the prechordal plate and to the notochord.

The process by which the anatomical structures of the axial mesoderm are generated and organized. Morphogenesis pertains to the creation of form.

The process by which DNA replication is started; this involves the separation of a stretch of the DNA double helix, the recruitment of DNA polymerases and the initiation of polymerase action.