CFM 2: Mitochondria

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CFM 2: Mitochondria
2015-09-08 22:13:46
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  1. Matrix of mitochondria have very (high/low) concentration of proteins
  2. Inner membrane of mitochondria is highly (permeable/impermeable)
    Impermeable (even protons can't get through)
  3. Outer membrane of mitochondria is highly (permeable/impermeable)
  4. What creates high permeability of mitochondrial outer membrane?
    VDACs (voltage dependent anion channels)
  5. How to isolate mitochondrial compartments
    • Suspend mitochondria in medium of low osmolarity
    • Influx of water causes inner membrane to swell (impermeable), causes outer membrane to rupture
    • Centrifugation leaves contents of intermembrane space in nonsedimenting fraction
    • Transfer of the rest of stuff to medium of high osmolarity to cause shrinkage - leaves you with mitoplast (mitochondria minus outer membrane) and small vesicles from ruptured outer membrane
    • Density-gradient centrifugation separates outer membrane from mitoplast
    • Disruption and centrifugation of mitoplast separates inner membrane from matrix
  6. 3 parts of inner membrane of mitochondria; how they differ in structure and function
    • Cristae membrane: part of the folds; rich in proteins involved in cell respiration
    • Cristae junctions: between cristae membrane and inner boundary membrane; contain MINOS
    • Inner boundary membrane: not part of the folds; rich in proteins involved in protein transport
  7. Mitoplast
    Mitochondria minus outer membrane
  8. MINOS in mitochondria
    • Mitochondria Inner Organizing System
    • Located in cristae junctions on inner membrane
    • Involved in generation of cristae and connect inner membrane to outer membrane
  9. What happens to mitochondria with mutant MINOS?
    Inner membrane not connected to outer membrane and no cristae junctions
  10. Lipids of mitochondria
    • Phosphatidylcholine
    • Phosphatidylethanolamine
    • Cardiolipin (mitochondria-specific phospholipid on inner membrane, with 4 fatty acids instead of 2, 2 glycerol groups, 2 phosphates, and anionic)
  11. Mitochondrial division is (reversible/irreversible)
    • Reversible
    • Fusion and fission are always happening
    • There is an equilibrium between fusion and fission
  12. Cardiolipin
    • Mitochondria-specific phospholipid located on inner membrane
    • 4 fatty acids instead of 2; 2 glycerols; 2 phosphates; overall negative charge (anionic)
  13. 3 diseases associated with changes in mitochondrial structure and function
    • Diabetes
    • Neurodegenerative diseases (Parkinson)
    • Aging
  14. Complexes on inner mitochondrial membrane contain proteins encoded by (mtDNA/nDNA/both); except for one complex (which one?), which contains proteins encoded by (mtDNA/nDNA/both)
    • Both
    • Except Complex II
    • Only nDNA
  15. Common features in diseases caused by mitochondrial DNA mutations
    • Myopathy
    • Cardiomyopathy
    • Neuropathy
  16. 3 unique aspects of mitochondrial genetics
    • Maternal inheritance
    • Heteroplasmy
    • Mitotic segregation
  17. Why is mtDNA maternally inherited?
    • Sperm injects nDNA into oocyte, but not mtDNA
    • Why? Sperm mitochondria have high ATP production for motility, oocyte mitochondria does not need that
  18. Heteroplasmy
    • Multiple copies of mtDNA in each cell
    • There can be a coexistence of mutated and normal mtDNA
    • At least 50% of the cell's mitochondria need to have the mutant DNA in order for disease phenotype
  19. Mitotic segregation of mtDNA
    • Since there is a random distribution of organelles during cell division, there is a non-equal distribution of normal and mutated mtDNA among daughter cells
    • So, there is a variable clinical presentation of mitochondrially inherited diseases
    • Clinical presentation changes with age because as cells continue to divide, distribution of mitochondria changes
  20. Mitochondrial DNA encodes how many polypeptides?