mitochondria

Question 1

general concepts

Answer 1

• seen them since 19th century
• challenge - lysosomes and mitoch co-sediment together
• tubular, long, branched
• tethered to microtubules
  
  • colchicine: polymerizes
    microtubules
• mitochondria and ER serve as reservoir for Ca2+

Question 2

mitochondria structure

Answer 2

1. outer membrane
   
   • fewer proteins
   • porins –> large, porous -
     5,000 Dalton
   • VDAC = voltage
     dependent anion channels
2. inner membrane
   
   • oxidative phosphorylation
   • ETC
   • cardiolipin (phospholipid)
     
     • 4 “legs”
     • increases electrical
       resistance
     • “glue” for ETC
       intermediates

Question 3

PIGBOS

Answer 3

• “microprotein” (54 AA)
• on outer mitochondrial membrane (green fluorescence)
• it communicates with the ER and regulates the UPR via the ER protein CLCC1
• loss of PIGBOS increases UPR leading to increased cell death

Question 4

ER associated MAMs (mitochondrial associated membranes)

Answer 4

• calcium homeostasis - rapid uptake of calcium by the VDACs in the outer membrane
• regulation of lipid metabolism
• regulation of autophagy and mitophagy
• diseases such as Alzheimer’s and Parkinson’s

Question 5

mitochondria undergo:

Answer 5

fission
- a way to distribute mitochondria into two daughter cells
- a way in which damaged portions of the mitoch can be eliminated

fusion
- may maintain a homogeneous pool of mitochondria in the cell
- could restore the function of damaged mitochondria
- may play a role in localization

Question 6

nanotubes

Answer 6

mitochondria can travel between two different cells using tunneling nanotubes

• can move on the microtubules

Question 7

mitochondrial permeability transition pore

Answer 7

• found in mitochondria
• contains adenine nucleotide transporter
• can open to release cytochrome C from mitochondrial matrix into cytoplasm
• release of cyt C precedes:
  
  • activation of caspase 3
  • conversion of
    procaspase 9 to caspase 9
  • apoptosis
    final step = activation of procaspase 3 to caspase 3

Question 8

Bcl-2 (B cell lymphoma)

Answer 8

• anti-apoptotic protein
• can block MPTP process
• patients resistant to chemo/radiation due to overexpression of Bcl-2

Question 9

cyclosporin A

Answer 9

• inhibits the opening of the MPTP
• immunosuppressant
• protects stem cells during storage and transport