Practice Questions

The conversion of amino acid carbon skeletons into metabolic intermediates like alpha-ketoglutarate requires enzymes located within the mitochondrial matrix.

The TIM23 complex is the primary translocase channel that threads unfolded precursor proteins across the inner mitochondrial membrane into the matrix.

Paternal mitochondria entering the egg are tagged with ubiquitin and selectively destroyed via mitophagy, ensuring that only maternal mitochondrial DNA survives.

Nuclear-encoded mitochondrial proteins use the Translocase of the Outer Membrane (TOM) and Translocase of the Inner Membrane (TIM) to cross both bilayers.

Proton flux through the Fo​ base forces the central gamma asymmetric shaft to spin inside the static α3​β3​ hexamer of the F1​ head, inducing conformational changes that forge ATP.

Proton leaks collapse the electrochemical gradient across the inner membrane, directly short-circuiting ATP synthesis.

Uncouplers dissipate the proton gradient without making ATP. Energy is lost as heat, driving the cell to burn oxygen faster to compensate.

These prokaryotic-like genetic traits strongly confirm that mitochondria evolved from ancient alpha-proteobacteria engulfed by primitive cells.

The electron transport chain complexes (I-IV) are embedded within the inner membrane folds (cristae) to easily interact with the chemical environment.

The soluble enzymes of the Krebs cycle reside inside the fluid matrix, with the sole exception of succinate dehydrogenase (bound to the inner membrane).