The mitochondrial electron transport chain (ETC) is a crucial component of cellular energy production, consisting of five main complexes: I, II, III, IV, and V, located in the mitochondrial inner membrane. The ETC transfers electrons through a series of redox reactions, ultimately reducing oxygen to water, while generating a transmembrane proton gradient that drives ATP synthase (Complex V) to produce ATP. The ETC is highly active in tissues with high energy demands, such as the heart and muscles. Specific expression of genes and genetic mutations can impact the functionality of the ETC, potentially leading to metabolic disorders, mitochondrial diseases, and other related conditions, such as neurodegenerative diseases and myopathies.