How does interphase prepare cells for mitosis

Best   Interphase itself is divided into three stages: G1 (growth 1), synthesis, and G2 (growth 2).

In G1, the cell continues to grow: the organelles double, the cell's volume increases and many proteins are translated. During the S phase, the cell's DNA is copied. In G2, the cell still continues growing.

There are also what you call checkpoint proteins during interphase. They ensure that the cell is ready even before entering prophase. If the checkpoint proteins don't see the cell as fit to undergo mitosis, it arrests