Module 9.3: Mitochondria Structure & Function

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Test 1 (9.3) — Mitochondria Structure & Function

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9.3 Mitochondria Structure — Test 1

Q1. Which biochemical event ensures the translocation of electrons from cytoplasmic NADH (produced in glycolysis) into the mitochondrion?✓ Malate–aspartate shuttle

Q2. The malate–aspartate shuttle specifically operates predominantly in:✓ Heart and liver

Q3. A yeast cell is chemically treated to remove all mitochondrial DNA. The likely outcome is:✓ Oxygen consumption is severely reduced or zero

Q4. Which shuttle, when operating, allows ~32 ATP from complete oxidation of one glucose?✓ Malate–aspartate shuttle

Q5. When ³H-NADH is added to a cell extract with mitochondria, radioactivity quickly appears in the matrix, but ¹⁴C-NADH gives none in the matrix. The best explanation is:✓ Reducing equivalents (H), not the NADH molecule, are carried in by a shuttle

Q6. Which one of the following is NOT a function of mitochondria-associated membranes (MAMs)?✓ Electron transport

Q7. The outer mitochondrial membrane is permeable to ions and solutes below ~10 kDa because of the presence of:✓ Porins (VDAC)

Q8. The malate–aspartate shuttle ultimately delivers cytosolic reducing equivalents to the matrix as:✓ NADH

Q9. The cristae of the inner mitochondrial membrane primarily serve to:✓ Increase the surface area for the electron transport chain and ATP synthase

Q10. The matrix of the mitochondrion contains all of the following EXCEPT:✓ The electron transport chain complexes

Q11. The inner mitochondrial membrane is characteristically:✓ Highly impermeable, requiring specific transporters

Q12. Mitochondria are described as semi-autonomous organelles because they:✓ Possess their own DNA and ribosomes and make some of their own proteins

Q13. Proteins encoded by the nucleus are imported into the mitochondrial matrix through the:✓ TOM and TIM translocase complexes

Q14. The endosymbiotic theory proposes that mitochondria evolved from:✓ Engulfed aerobic bacteria (α-proteobacteria)

Q15. The glycerol-3-phosphate shuttle delivers cytosolic reducing equivalents into the ETC as:✓ FADH₂ (entering at the ubiquinone level)

Q16. Cardiolipin, a signature lipid of the inner mitochondrial membrane, is important for:✓ Stability and function of ETC complexes and ATP synthase

Q17. During apoptosis, the key molecule released from the mitochondrial intermembrane space to trigger the cascade is:✓ Cytochrome c

Q18. The phosphate carrier of the inner mitochondrial membrane imports inorganic phosphate (Pi) in symport with:✓ Protons (H⁺)

Q19. Compared with the outer membrane, the inner mitochondrial membrane has a much:✓ Higher protein-to-lipid ratio

Q20. Reactive oxygen species (ROS) in the cell are generated largely as a by-product of:✓ Electron leakage from the mitochondrial electron transport chain