Mitochondrial DNA is primarily involved in coding for proteins needed for protein complexes of the electron transport chain and ATP synthase. Therefore, mutations in mitochondrial genes would most affect .

Generation of ATP in muscle cells.

Explanation:

Mitochonria is the power house of the cells, in this organelle of cell the biochemical process of respiration and generation of energy occurs. Energy produces in the form of ATP.

Mitochonrial DNA coded for specific protein complexes which are responsible for the process of electron transport chain and ATP synthase. If in the mitochondrial genes mutation occurs it will affect the production of ATP (energy) in muscle cells.