Mitochondria

Question 1

What is the endosymbiont hypothesis concerning mitochondria?

Answer 1

• the inner mitochondria membrane is derived from bacteria

- outer membrane derived from eukaryotic cell

Question 2

Which mitochondrial membrane is less-permeable and contains most of the machinery for oxidative phosphorylation?

Answer 2

the inner membrane

Question 3

How permeable is the outer mitochondrial membrane?

Answer 3

semi-permeable

Question 4

What are cristae in the mitochondria?

Answer 4

infoldings that increase the surface area of the inner membrane

Question 5

What is the matrix in the mitochondria?

Answer 5

the central space of the mitochondria

Question 6

How are mitochondrial proteins (synthesized in the nucleus) transported to their final location?

Answer 6

• translocate of outer membrane (TOM) - passive

- translocate of inner membrane (TIM) - ATP dependent

Question 7

What role does fusion play for mitochondria?

Answer 7

repairing damaged mitochondria

Question 8

What role does fission play for mitochondria?

Answer 8

required for mitophagy (selective degradation of mitochondria by autophagy)

Question 9

What transports ATP out of the mitochondria once it’s made by ATP synthase?

Answer 9

ATP-ADP antiporter

Question 10

What induces permeabilization of he outer mitochondria membrane?

Answer 10

Bak/Bax dependent upon cell damage

Question 11

What does Bak/Bax dependent permeabilization of the outer mitochondria membrane lead to?

Answer 11

cytochrome c release -> binds to several cytoplasmic proteins forming an apoptosome

Question 12

What does the apoptosome do in mitochondria?

Answer 12

• activates caspases and initiates apoptosis

Question 13

What do the mitochondria do during ischemic injury?

Answer 13

promote necrotic cell death due to MPTP-dependent permeabilization of inner and outer mitochondria membranes -> cytochrome release and elimination of the proton gradient

Question 14

What do damaged mitochondria result in?

Answer 14

• lack of ATP production

- excessive amounts of reactive oxygen

Question 15

What are the three levels at which mitochondria quality is strictly controlled?

Answer 15

• mitochondrial proteases are responsible for recognizing and degrading misfolded proteins
• damaged mitochondria can be fixed by fusing with healthy mitochondria or eliminated by mitophagy
• extensive damage -> mitochondria induces apoptotic cell death

Question 16

What two diseases are caused by mutations in mitochondria fusion machinery?

Answer 16

• autosomal dominant optic atrophy

- Charcot-marie-tooth neuropathy type 2A