Mitochondria are often called the “powerhouses of the cell,” but that label only scratches the surface. These dynamic organelles perform a range of critical functions that influence energy production, cell survival, metabolic balance, and even body temperature. Understanding mitochondria lays the foundation for appreciating how mitochondrial diseases affect the body.
1) Energy Production (ATP Generation)
Mitochondria generate ATP—the cell’s energy currency—through aerobic respiration, involving:
The Krebs (citric acid) cycle, which harvests electrons from nutrients.
The electron transport chain (ETC), which uses those electrons to power ATP synthase and produce ATP.
2) Apoptosis (Programmed Cell Death)
Mitochondria help regulate apoptosis, a controlled process of cell self-destruction needed for development, tissue renewal, and cancer prevention. They release pro-apoptotic signals when cellular damage is irreparable.
3) Calcium Homeostasis
Mitochondria buffer and modulate intracellular calcium, sustaining:
Muscle contraction
Cell signaling
Synaptic neurotransmission Disrupted mitochondrial calcium handling can trigger arrhythmias, muscle weakness, and nerve dysfunction.
4) Heat Production (Thermogenesis)
In brown adipose tissue, mitochondria generate heat via uncoupling proteins that allow protons to dissipate energy as heat rather than ATP—important for temperature regulation, especially in infants.
5) Metabolic Synthesis
Mitochondria support synthesis of critical biomolecules:
Heme (for hemoglobin and cytochromes)
Cholesterol and steroid precursors
Certain neurotransmitters and amino acids
Mitochondria possess their own circular DNA (mtDNA), distinct from nuclear DNA (nDNA), reflecting their origin as symbiotic bacteria. Each cell contains hundreds to thousands of mitochondria, each carrying multiple mtDNA copies—an arrangement that influences how mitochondrial diseases develop.
Because mitochondria are central to energy and cell survival, failures in mitochondrial function ripple across systems—especially those with high energy demands like the brain, heart, and muscles.
Mitochondria are not merely batteries—they are sophisticated control centers coordinating energy, metabolism, and cellular fate. Their complexity explains both the breadth and variability of mitochondrial disease manifestations.