Practice question

Mitochondrial DNA encodes 13 hydrophobic core subunits essential for electron transport chain, distributed across complexes. NADH dehydrogenase genes ND1, ND2, ND3, ND4, ND4L, ND5 and ND6 encode subunits of complex I, NADH:ubiquinone oxidoreductase, largest respiratory complex initiating electron transfer from NADH to ubiquinone and pumping protons. Remaining genes include cytochrome b for complex III, COX1-3 for complex IV and ATP6, ATP8 for complex V. Complex II is entirely nuclear encoded. Mutations in ND genes cause Leber hereditary optic neuropathy and mitochondrial encephalomyopathies.