Question

1. where does dna replication happen?
2. when does dna replication happen?

Explanation:

DNA replication occurs in the nucleus of eukaryotic cells (where the DNA is located). In prokaryotic cells (which lack a nucleus), it occurs in the cytoplasm.

For the timing, in eukaryotes, DNA replication happens during the S - phase (synthesis phase) of the cell cycle. This is before cell division (mitosis or meiosis) so that each new cell gets a complete set of genetic information.

Answer:

1. In the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells.
2. During the S - phase of the cell cycle.