Mitochondria Shizz

Question 1

Suggested origin of mitochondria:

Endosymbiont Hypothesis

Answer 1

Mitochondria showed up by way of endocytosis of oxidative-phosphorylating bacteria by our distant ancestor(s)

• outer membrane: eukaryotic origin
• Inner membrane: engulfed bacteria

Question 2

Mitochondria functions

Answer 2

1. Generation of ATP
2. Apoptosis
3. Regulation of Intracellular Ca2+

Question 3

How are mitochondrial proteins, imported into the mitochondrial matrix?

Answer 3

Imported via TOM and TIM complexes.

Question 4

Between TIM and TOM,

• Which one is passive?
• Which one is ATP-dependent?

Answer 4

passive: TOM

ATP dep: TIM

Question 5

Fusion of mitochondria plays key role in?

Answer 5

Repair!

Fusing with healthy mitochondria to repair damaged mitochondria
-thus “fixing” it

Question 6

Fission of mitochondria plays key role in?

Answer 6

Mitophagy: targeting mitochondria for degredation via autophagy

Question 7

Fusion and Fission are dependent on cellular _____.

List the proteins involved

Answer 7

GTPases:

Fusion - Mfn + OPA1
Fission - Fis1 + Drp

Question 8

Describe how electrons are released from NADH during respiration in mitochondria and what this generates

Answer 8

1. NADH is oxidized, freeing up H+
2. Protons from mt matrix are pumped across inner membrane
3. this generates proton [ ] gradient + electric potential

Question 9

Describe basic principles of ATP production in mitochondria

Answer 9

ATP is synthesized from:
ADP and Pi coupled with electron transfer (proton gradient/electric potential)

-This is achieved by ATP synthase in IMM (inner Mt mem)

Question 10

What does ATP synthase consist of?

Answer 10

F0: in IMM and forms proton channel

F1: bound to F0 and is actual enzyme that makes ATP

Question 11

How does F0 function?

Answer 11

F0 uses the E of proton movement through the channel to generate ATP

Question 12

How is ATP transported out of the mitochondria?

Answer 12

ATP-ADP antiporter

Question 13

Describe basic mechanism of apoptotic cell death regulation by mitochondria

Answer 13

1. cell damage occurs
2. induces Bak/Bax- dependent permeabilization of OMM
3. releases cytochrome c
4. cytochrome c binds to apoptosomes
5. activates caspases (initiating apoptosis)

Question 14

Describe basic mechanism of necrotic cell death regulation by mitochondria

Answer 14

1. Ischemic injury
2. Induces MPTP-dependent permeabilization of IMM and OMM
3. Cytochromes are released
4. eliminates protein gradient

Question 15

In absence of proton gradient, ATP synthase is converted into what?

Answer 15

ATPase

- leads to ATP depletion and necrosis

Question 16

Damaged mitochondria generate excessive amts of?

What does it do?

Answer 16

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

Question 17

3 Principles of Mitochondrial quality control during damage

Answer 17

1. mitochondrial proteases (mAAA, iAAA, Lon) recognizes and degrades misfolded proteins
2. “fixing” by fusing with healthy mt
3. inducing apoptotic cell death

Question 18

role of mt in sensecense

Answer 18

ROS generation by damaged mt induces sensescense by oxidating proteins, lipids, and DNA

Question 19

Mitochondria-related diseases and gene or protein that is affected

Answer 19

1. Optic atropy
   
   • OPA1
2. Charcot-Marie-Tooth neuropathy type 2A
   
   • Mfn2
3. hereditary spastic paraplegia
   
   • mAAA proteases

Question 20

How does arsenic affect mitochondria?

Answer 20

Inhibits oxidative phosphorylation and inhibiting ATP production