When chromosomes are duplicated before mitosis or meiosis, the amount of DNA in the
nucleus is tripled

Ineed more info for this, i don’t quite understand what you’re asking.

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.

The anwser is the universe