Mitochondria are central to cellular metabolism, playing a key role in energy production and maintaining cellular homeostasis. They are dynamic organelles that respond to both intrinsic and extrinsic stresses, altering cell and organismal function through metabolic signaling. Mitochondrial dysfunction is linked to a wide range of diseases and aging, with over 40% of mitochondrial proteins associated with human diseases. Mitochondria have a complex structure, including two membranes and several compartments, each with distinct functions. The inner membrane houses the electron transport chain and ATP synthase, essential for ATP production. Mitochondria also regulate redox balance through NAD+ and glutathione, which are critical for cellular metabolism and stress responses. Mitochondrial metabolic plasticity allows them to adapt to different cellular needs, such as oxidative phosphorylation during energy production or fatty acid oxidation in quiescent cells. Mitochondria interact with other organelles, such as the endoplasmic reticulum, to exchange lipids, ions, and metabolites, regulating mitochondrial dynamics and function. Mitochondrial lipid biogenesis is essential for maintaining mitochondrial structure and function, with pathways for phosphatidylcholine, cardiolipin, and other lipids playing key roles. Mitochondrial protein biogenesis involves both nuclear and mitochondrial-encoded proteins, with nuclear-encoded proteins being imported into mitochondria through specific pathways. Mitochondrial translation defects can lead to a variety of diseases, including cardiomyopathies and neurodegenerative disorders. Complex I, a key component of the respiratory chain, is a large, multi-subunit complex that requires coordinated assembly of nuclear and mitochondrial-encoded proteins. Defects in complex I can lead to severe diseases such as Leigh syndrome. Mitochondrial lipid transport at membrane contact sites allows for the exchange of lipids between mitochondria and other organelles, contributing to cellular lipid homeostasis. Understanding mitochondrial biology is crucial for developing new therapies for mitochondrial diseases and aging-related disorders.Mitochondria are central to cellular metabolism, playing a key role in energy production and maintaining cellular homeostasis. They are dynamic organelles that respond to both intrinsic and extrinsic stresses, altering cell and organismal function through metabolic signaling. Mitochondrial dysfunction is linked to a wide range of diseases and aging, with over 40% of mitochondrial proteins associated with human diseases. Mitochondria have a complex structure, including two membranes and several compartments, each with distinct functions. The inner membrane houses the electron transport chain and ATP synthase, essential for ATP production. Mitochondria also regulate redox balance through NAD+ and glutathione, which are critical for cellular metabolism and stress responses. Mitochondrial metabolic plasticity allows them to adapt to different cellular needs, such as oxidative phosphorylation during energy production or fatty acid oxidation in quiescent cells. Mitochondria interact with other organelles, such as the endoplasmic reticulum, to exchange lipids, ions, and metabolites, regulating mitochondrial dynamics and function. Mitochondrial lipid biogenesis is essential for maintaining mitochondrial structure and function, with pathways for phosphatidylcholine, cardiolipin, and other lipids playing key roles. Mitochondrial protein biogenesis involves both nuclear and mitochondrial-encoded proteins, with nuclear-encoded proteins being imported into mitochondria through specific pathways. Mitochondrial translation defects can lead to a variety of diseases, including cardiomyopathies and neurodegenerative disorders. Complex I, a key component of the respiratory chain, is a large, multi-subunit complex that requires coordinated assembly of nuclear and mitochondrial-encoded proteins. Defects in complex I can lead to severe diseases such as Leigh syndrome. Mitochondrial lipid transport at membrane contact sites allows for the exchange of lipids between mitochondria and other organelles, contributing to cellular lipid homeostasis. Understanding mitochondrial biology is crucial for developing new therapies for mitochondrial diseases and aging-related disorders.