Mitochondria

Question 1

Where are the majority of mitochrondrial proteins encoded? Synthesized?

Answer 1

In the nucleus. Synthesized in the cytosol

Question 2

Which membrane is most permeable? Where is derived from?

Answer 2

Outer membrane. Derived from eukaryotic cell

Question 3

Which membrane is least permeable? Where is it derived from? What other machinery is found there?

Answer 3

Inner membrane least permeable. Derived from bacteria. Also contains most of the machinery of oxidative phosphorylation

Question 4

How are mitochondrial proteins imported into the matrix?

Answer 4

1st through the TOM (translocase of outer membrane) then through TIM (translocase of inner membrane)

Question 5

Which translocase is ATP-dependent?

Answer 5

TIM (TOM is passive)

Question 6

What role does mitochondrial fusion play?

Answer 6

Key role in repairing damaged mitochondria

Question 7

What role does mitochondrial fission play?

Answer 7

Required for mitophagy (degradation of mitochondria by autophagy)

Question 8

What are Mfn and OPA1? What are they required for?

Answer 8

Cellular GTPases. Requiredfor mitochondrial fusion

Question 9

What are Fis1 and Drp? What are they required for?

Answer 9

Cellular GTPases. Requiredfor mitochondrial fission

Question 10

Free energy released during oxidation of glucose is stored in NADH. Where does energy released from NADH go?

Answer 10

Used to pump protons from matrix across inner membrane. So energy from NADH is stored both as an electric potential and a proton concentration gradient in mitochondria

Question 11

What are the two main parts of ATP synthase?

Answer 11

F1 and F0.

Question 12

What does ATP synthase do?

Answer 12

Uses the proton gradient and electric potential to synthesize ATP

Question 13

What does F0 do?

Answer 13

Protein complex that spans the inner mitochondrial membrane and forms a proton channel

Question 14

What does F1 do?

Answer 14

Protein complex that is bound to F0 and is an actual enzyme that make ATP

Question 15

How many protons are needed to generate one ATP molecule?

Answer 15

3 protons per ATP

Question 16

Once ATP is made how is it transported out of the mitochondria?

Answer 16

via the ATP-ADP antiporter

Question 17

How are mitochondria involved in apoptosis?

Answer 17

Cell damage induces Bak/Bax-dependent permeabilization of outer mitochondria membrane. Leads to cytochrome c release

Question 18

What is the apoptosome made from? What does it do?

Answer 18

Made from cytochrome c and other cytoplasmic proteins. Apoptosome activates caspases and thus initiates apoptosis

Question 19

How do mitochrondria promote necrotic cell death?

Answer 19

Ischemic injury results in MPTP-dependent permeabilization of inner and outer mitochondria membranes. Results in cytochrome release AND elimination of proton gradient. No proton gradient means no ATP production and also converts ATP synthase into ATPase (uses up available ATP). Leads to ATP depletion and necrosis

Question 20

What else is released when mitochondria are damaged? What does it do?

Answer 20

Reactive oxygen (ROS). ROS causes cell damage and senescence by oxidating various cellular proteins, lipids and DNA.

Question 21

What are some mitochondrial proteases responsiblef for recognizing and degrading misfolded proteins?

Answer 21

mAAA; iAAA and Lon

Question 22

What are the 3 levels of mitochondria quality control?

Answer 22

1. mitochondrial proteases (mAAA; iAAA and Lon) 2. mitochondrial fusion or mitophagy 3. apoptotic cell death if damage is too extensive

Question 23

Which 2 diseases result from mutations in mitochondria fusion machinery?

Answer 23

Autosomal dominant optic atrophy and Charcot-Marie-Tooth neuropathy type 2A

Question 24

Which gene is mutated in autosomal dominant optic atrophy?

Answer 24

OPA1 gene

Question 25

Which gene is mutated in Charcot-Marie-Tooth?

Answer 25

Mfn2 gene

Question 26

What disease results from mutations in mAAA protease?

Answer 26

hereditary spastic paraplegia

Question 27

How does arsenic work?

Answer 27

Inhibits oxidative phosphorylation and ATP production

Question 28

What are the 3 functions of mitochondria?

Answer 28

Generation of ATP. Apoptosis. Regulation of intracellular Ca ions