Mitochondria

Question 1

Principal sources of ATP

Answer 1

Fatty acids and glucose

Question 2

Endosymbiont hypothesis

Answer 2

Inner mito mem is from bacteria, outer mem is from eukaryotic cell.
Mitochondria arose because of endocytosis of bacteria capable of oxidative phosphorylation.

Question 3

Outer membrane

Answer 3

Semi-permeable

Question 4

Inner membrane

Answer 4

less permeable, contains most of the machinery needed for oxidative phosphorylation.
Has cristae that increase SA.
Electron transfer.
Electrons from matrix are pumped across the inner mem.
Where ATP synthase is.

Question 5

Matrix

Answer 5

Central space. Contains mito DNA. Has high proton gradient inside (outside is low)… nec. for ATPsynthase.

Question 6

Where are mito proteins synthesized?

Answer 6

Majority in nucleus. Get into mito via TOM (passive. Translocase of outer mem) and TIM (ATP) (translocase of..)

Question 7

Fission

Answer 7

Cell dividing into 2 parts that make new cells.

Required for mitophagy. Depends on GTPase. Uses Fis1 and Drp.

Question 8

Fusion

Answer 8

GTPase. Mfn and OPA1.

Question 9

Electron transfer

Answer 9

Mito electrons go from NADH to O2 to H20 during respiration.

Question 10

NADH

Answer 10

Reducing enzyme. Holds the energy from glucose oxidation.

Question 11

Mitochondria fx.

Answer 11

ATP generation, regulation of intracellular Ca, apoptosis.

Question 12

Oxidative phosphorylation

Answer 12

Oxidation of nutrients to make ATP.
I. NADH-CoQ reductase
II. Succinate-CoQ reductase
III. CoQ-cytochrome c reductase
IV. Cytochrome c oxidase
The energy released by electrons flowing through electron transport chain is used to transport H+ across the inner mito mem (electron transport)
This generates potential energy in the form of a pH gradient and an electrical potential across this membrane.

Question 13

ATP synthase

Answer 13

Makes ATP from ADP. ON INNER MEM.
Uses potential energy from electron transport chain… tapped by allowing H+ to flow back across the membrane down this gradient, through a large enzyme called ATP synthase; this process is known as chemiosmosis.
This rxn is driven by H+ flow, which forces rotation of a part of the enzyme; ATP synthase is a rotary mechanical motor.
2 main parts: F1 (enzyme that makes ATP) and is bound to F0 (inner mito mem proton channel).

Question 14

How does ATP get out of mito

Answer 14

ATP-ADP antiporter

Question 15

Mitochondria and cell damage

Answer 15

Cell damage –> Bak/Bax permeate outer mito mem –> cytochrome C released and binds cytoplasmic proteins to form –> apoptosome –> caspase activation –> death by apoptosis.

Question 16

Mitochondria and ischemic damage

Answer 16

Mito can promote necrosis.
Ischemic injury –> MPTP dependent permeatio of inner/outer mito mem –> cytochrome release –> H+ gradient elimination –> blocked ATP production –> ATPsynthase converted to ATPase so use up available ATP —> leads to ATP depletion and necrosis.

Question 17

Why is mito quality controlled?

Answer 17

Damage mito can’t produce ATP and produce lots of ROS, leads to cell damage and senescence by oxidating various cell proteins, lipids, DNA.

Question 18

How is mito’s quality controlled?

Answer 18

mito proteases (mAAA, iAAA, and Lon) recognize/degrade misfolded proteins.
Damaged mito can be “fixed” by fusing with healthy mito.
Really damaged ones eliminated with mitophagy.
Or can induce apoptosis.

Question 19

Mutations in mito fusion machinery cause…?

Answer 19

AD optic atrophy

Charco-marie tooth type 2A

Question 20

mutation in mAAA

Answer 20

hereditary spastic paraplegia

Question 21

Arsenic

Answer 21

Inhibits oxidative phosphorylation and thus ATP production.