Each horizontal row in a pedigree chart represents a mating. a generation. several siblings. several characteristics.

Each horizontal row in a pedigree chart represents "a generation" although it should be noted that pedigree charts can vary according to their purpose. 

The titanic is the answer

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.