Mitochondria is commonly depicted as the powerhouse of the cell given its ability to produce ATP through oxidative phosphorylation. The other fundamental feature of this powerhouse lies in its morphology and its exceptional plasticity. Mitochondria assemble in a remarkably dynamic network whose tubular morphology is conditioned by an equilibrium between fission and fusion events of their membranes. These processes are essential to shape the ultra-structure of the mitochondrial compartment and are thus also crucial for all mitochondrial functions, including respiration. Combining cutting edge technologies of cell biology, quantitative imaging and biophysics, our multi-disciplinary consortium reveals and explores an intimate but hidden link between the reorganization of mitochondrial morphology, oxidative phosphorylation and the homeostasis of mitochondrial DNA in the model organism Saccharomyces cerevisiae.