Down the middle.
helicase
A DNA molecule splits in the 5' to 3' direction during replication. Each strand acts as a template for the synthesis of a new complementary strand.
At a specific location known as the "replication fork," DNA splits or "unzips" during replication. The split of the double-stranded DNA molecule into two single strands occurs at the replication fork. Due to this division, the replication apparatus may access and duplicate each of the single DNA strands, resulting in the creation of two identical DNA molecules that each include one original and one freshly manufactured strand. DNA replication is necessary for cell division and the genetic information transfer to daughter cells.
The stage at which a DNA molecule is split down the middle is replication. The first step in making a protein is RNA copying DNA.
helicase enzymes
It becomes duplicated.
Water molecule is split during the light reactions of photosynthesis to release oxygen.
DNA polymerase
Glucose
down the middle
I can find no reference to a molecule used in "pf" replication. Do you have another term in mind? Please resubmit your question if you do.
In the nucleus during the S phase of interphase.