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7.1 Mitochondrial Structure & Import — Test 1
Q1. The term 'mitochondria' was coined by:✓ Carl Benda
Q2. The inner mitochondrial membrane is characterized by the presence of an unusual phospholipid:✓ Cardiolipin
Q3. A eukaryotic cell is fractionated and ultracentrifuged. One fraction is found to be rich in cardiolipin. Identify the organelle in this fraction:✓ Mitochondria
Q4. The outer mitochondrial membrane is permeable to ions and solutes smaller than ~10 kDa due to the presence of:✓ Porins
Q5. Which of the following organelles contain DNA?✓ Nucleus, mitochondria and chloroplast
Q6. Which evidence suggests that mammalian mitochondria originated from an endosymbiotic proteobacterium?✓ Circular DNA
Q7. Which type of genes is NOT known in any mitochondrial genome?✓ Glycolytic genes
Q8. Which statement about mitochondrial genomes is FALSE?✓ They contain the genes necessary for all mitochondrial functions
Q9. Introns are present in the mitochondrial DNA of which organism?✓ Yeast
Q10. Which statement about mitochondrial protein import is TRUE?✓ Mitochondrial proteins cross the membrane in an unfolded state
Q11. Proteins that are sorted to the mitochondrial matrix are ______ in nature:✓ Amphipathic
Q12. Which protein is most likely to be found in the inter-membrane space (IMS) of mitochondria? A protein containing:✓ An N-terminal matrix-targeting sequence followed by a cleavable hydrophobic sequence that blocks complete translocation
Q13. Which dye/stain is used to visualize mitochondria in a cell?✓ Janus Green B
Q14. Hydrogenosomes are:✓ Organelles that produce hydrogen and ATP from pyruvate
Q15. Which cellular event is NOT directly associated with mitochondria?✓ Protein degradation
Q16. Which organelle(s) is/are involved in maintaining the Ca²⁺ level of the cell?✓ Mitochondria and endoplasmic reticulum
Q17. The main function of mitochondria is:✓ Respiration
Q18. Which cell type has the highest mitochondrial activity?✓ Neuron
7.2 Oxidative Phosphorylation — Test 2
Q19. F₀–F₁ particles (oxysomes) are located on the:✓ Inner mitochondrial membrane
Q20. The enzyme succinate dehydrogenase is associated with which respiratory complex?✓ Complex II
Q21. Cyanide or azide (used in poisoning) irreversibly bind to ______, the critical link between aerobic respiration and oxygen:✓ Cytochrome c oxidase
Q22. When cells are treated with cyanide, which organelle has the highest cyanide concentration inside?✓ Mitochondria
Q23. Which is the only non-protein component of the electron transport system?✓ Coenzyme Q
Q24. During respiration, the correct sequence of cytochrome electron acceptors in ATP synthesis is:✓ Cyt b, c, a, a₃
Q25. Which process makes direct use of oxygen?✓ Electron transport
Q26. In aerobic respiration, the complete oxidation of one molecule of glucose yields approximately how many ATP?✓ 36
Q27. How many times more energy is gained in aerobic respiration compared with anaerobic respiration?✓ 18
Q28. ATP is formed from ADP by the direct transfer of a phosphoryl group from phosphoenolpyruvate. This type of reaction is called:✓ Substrate-level phosphorylation
Q29. In the absence of oxygen, the metabolic fate of pyruvic acid will be that:✓ It will be utilized for the re-oxidation of NADH
Q30. The entry of ADP into mitochondria is coupled to the exit of ATP by the:✓ ATP–ADP translocase
Q31. A significant (large) membrane potential is present across the:✓ Mitochondrial inner membrane
Q32. The membrane potential in intact mitochondria will favour the accumulation of which compound after passage through the inner membrane?✓ A cationic dye
Q33. Membrane potential in mitochondria (critical for oxidative phosphorylation) is monitored by:✓ Measuring the distribution of labelled ions across the membrane
Q34. The dye used in flow cytometry for assessing mitochondrial membrane potential is:✓ Rhodamine
Q35. The citric acid (Krebs / TCA) cycle takes place in the:✓ Mitochondrial matrix
Q36. In the TCA cycle, ATP/GTP is produced directly (substrate-level phosphorylation) at the step catalysed by:✓ Succinyl-CoA synthetase (succinate thiokinase)
Q37. For each acetyl-CoA oxidized in one turn of the TCA cycle, the yield of reduced coenzymes and nucleotide is:✓ 3 NADH, 1 FADH₂ and 1 GTP
Q38. Fatty-acid β-oxidation occurs primarily in the:✓ Mitochondrial matrix
Q39. The product of each round of mitochondrial β-oxidation that feeds into the TCA cycle is:✓ Acetyl-CoA
Q40. Long-chain fatty acids are carried across the inner mitochondrial membrane for β-oxidation by the:✓ Carnitine shuttle
Q41. The chemiosmotic theory of oxidative phosphorylation was proposed by:✓ Peter Mitchell
Q42. According to the chemiosmotic theory, ATP synthesis by ATP synthase is driven directly by:✓ A proton (H⁺) electrochemical gradient across the inner membrane
Q43. 2,4-Dinitrophenol (DNP) increases oxygen consumption but abolishes ATP synthesis because it:✓ Acts as an uncoupler, carrying protons across the inner membrane and dissipating the gradient
Q44. Oligomycin blocks mitochondrial ATP synthesis by inhibiting:✓ The F₀ proton channel of ATP synthase
Q45. Which respiratory complex is also called NADH–ubiquinone oxidoreductase (NADH dehydrogenase)?✓ Complex I
Q46. Which electron-transport-chain complex does NOT pump protons across the inner mitochondrial membrane?✓ Complex II
7.3 Mitochondrial Dynamics — Test 3
Q47. Mitochondria continually remodel their network through two opposing processes:✓ Fusion and fission
Q48. Fusion of the OUTER mitochondrial membrane is mediated by:✓ Mitofusins (Mfn1 and Mfn2)
Q49. Fusion of the INNER mitochondrial membrane is mediated by:✓ OPA1
Q50. Mitochondrial fission is driven by a cytosolic dynamin-related GTPase called:✓ DRP1 (Drp1 / Dnm1)
Q51. Which outer-membrane protein acts as a receptor/adaptor that recruits DRP1 to drive mitochondrial fission?✓ Fis1 / Mff
Q52. Long-distance transport of mitochondria along axonal microtubules toward the plus end (anterograde) is powered by:✓ Kinesin
Q53. The outer-membrane GTPase that links mitochondria to motor adaptors and, by sensing Ca²⁺, halts mitochondrial movement is:✓ Miro (with the adaptor Milton/TRAK)
Q54. Damaged or depolarized mitochondria are selectively removed by autophagy in a process called:✓ Mitophagy (commonly via the PINK1/Parkin pathway)
Q55. In yeast, the protein complex that physically tethers the endoplasmic reticulum to mitochondria is the:✓ ERMES complex
Q56. Mitochondria-associated membranes (MAMs) are found at the:✓ Interacting region between mitochondria and the endoplasmic reticulum
Q57. Which activity is associated with mitochondria-associated ER membranes (MAM)?✓ Phospholipid metabolism
Q58. Mutations in Mfn2, a mitochondrial fusion protein, cause the inherited peripheral neuropathy:✓ Charcot–Marie–Tooth disease type 2A
Q59. Mutations in OPA1, the inner-membrane fusion protein, most commonly cause:✓ Autosomal dominant optic atrophy