The process in which DNA-dependent DNA replication is started; this begins with the ATP dependent loading of an initiator complex onto the DNA, this is followed by DNA melting and helicase activity. In bacteria, the gene products that enable the helicase activity are loaded after the initial melting and in archaea and eukaryotes, the gene products that enable the helicase activity are inactive when they are loaded and subsequently activate.

The maintenance of the integrity of extrachromosomal plasmid DNA; includes processes that ensure plasmids are retained in the daughter cells after cell division.

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an electromagnetic radiation stimulus. Electromagnetic radiation is a propagating wave in space with electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation.

Any of the protein-DNA complexes that contain a DNA helicase and associated protein(s) at the origin of replication, and build up to assembling the core primosome. The associated protein(s) chaperone the helicase to the DNA, and assembly of the pre-primosome is essential for the initiation or restart of replication. Pre-primosome complexes lack a primase component.