Mitochondria

Question 1

1. Describe the origin, basic structure and fission/fusion of mitochondria.
2. Describe the basic machinery of mitochondria import.
3. State the basic principles of electron transport and ATP production in mitochondria
4. Explain the basic mechanisms of cell death regulation by mitochondria.
5. State the principles of mitochondria quality control.
6. Describe the role of mitochondria in senescence and some of the mitochondria-related diseases.

Answer 1

x

Question 2

Mitochondria Functions:

Answer 2

1) Generation of ATP
2) Apoptosis
3) Regulation of intracellular Ca ions

Question 3

The outer membrane of mitochondria is _____, which means what?

The inner membrane is ______, and have ____ channels.

Answer 3

Leaky. Small molecules found in the cytoplasm will also be found between the outer and inner membranes in the same concentrations.

Very tight, gated.

Question 4

____% of mitochondrial proteins are encoded by the genome. The remainder are encoded by the mitochondrial dna.

Answer 4

90

Question 5

GIP is import channel with “guge haping” hole in it. Where does it live and what does it do?

Answer 5

GIP (General Import Pore) is a non-gated always open channel in the outer mitochondrial membrane. Proteins chaperoned through, small molecules come through freely. Responsible for the cytosolic “matching” (leakiness) of the outer membrane.

!! ALSO known as TOM (chaperone proteins that encircle pore) !!

Question 6

Since majority of mitochondrial proteins are encoded in nucleus, these proteins are synthesized in cytosol and imported via TOM (translocase of outer membrane) and TIM (translocase of inner membrane) complexes. Transport through TOM is ____, while transport through TIM is ____.

Answer 6

passive; ATP-dependent

TOM=loosey goosey with big hole
TIM=Really tight channel with gate. ATP dependent

Question 7

Proteins targeted to the mitochondria have a targeting sequence attached. This is called the ____. By what proteins is it recognized?

Answer 7

Mitochondrial Targeting Sequence

Question 8

How do TIM23 and TIM22 allow large proteins to come through the pore without any leakiness of small ions?

Answer 8

mtHSP70 (not to be confused with cytosolic HSP70) literally pulls them through forcefully, denaturing them as necessary. The large proteins thus plug the hole allowing the tightly gated channels to retain membrane integrity. [mtHSP70 is an ATPase.]

“Shove the protein in, close the pore”

Question 9

Mutations that inhibit mitochondrial fusion will result in ______?

Answer 9

A variety of different neuropathies. Neuronal transport is very ATP dependent. Mitochondria fusion/fission is very important.

Question 10

Mutations in OPA1 gene causes? (not LO)

Answer 10

autosomal dominant optic atrophy

Question 11

Mutations in Mfn2 gene causes? (not LO)

Answer 11

Charcot-Marie-Tooth neuropathy type 2A

Question 12

Anaerobic metabolism of glucose metabolism leads to _____?

Answer 12

2 pyruvate. O2 independent. Occurs in the cytosol.

Question 13

Citric acid cycle generates? Where does this occur?

Answer 13

Inside inner mitochondrial membrane.
3 NADH
1 FADH
Acetyl CoA

Question 14

Oxidative phosphorylation does/does not create ATP directly.

Answer 14

Does not. Responsible for reducing NAD and FAD, as well as creating the proton gradient

Question 15

Oxidative phosphorylation has how many subunits? What generally happens?

Answer 15

4. Each pumps a proton and donates an electron to the next subunit. By running electrons through, move 3 protons from the inner space to the outer space, and use one proton from inner space to make one water. Inner space is poorer by 4 protons, outer space is richer by 3. (change of 7 protons)

Question 16

Every spin of ATP synthetase makes ____ ATP.

Answer 16

1. alpha subunit seems to do the work, be the important part

Question 17

Role of Mitochondria in Cell Death

Answer 17

1) Regulation of cytosolic calcium
2) Generation of reactive oxygen (ROS)
3) Supply of energy
4) Release of cytochrome c and activation of apoptosome

Question 18

Cytochrome C is present in the ____ in a healthy cell.

Answer 18

Inner mitochondrial membrane.

Question 19

If Cytochrome C in the cytosol is oxidated, the cell will ____. Reduced Cytochrome C in the cytosol will____.

Answer 19

Die via apoptosis; revert to a living cell, not undergo apoptosis. ATP is required to reduce cytochrome C (necrosis = no ATP so cannot reverse)

Question 20

At what 3 levels are mitochondria controlled (quality control?)

Answer 20

Molecular, organellular, cellular.

Question 21

Regarding mitochondrial quality control: Several mitochondrial proteases, such as (3) are responsible for recognizing and degrading misfolded proteins. Second, damage mitochondria can be “fixed” by (2). Finally, if mitochondria damage is extensive, mitochondria induces ____.

Answer 21

mAAA, iAAA and Lon

fusing with healthy mitochondria, or can be eliminated by mitophagy

apoptotic cell death

Question 22

Damaged mitochondria not only is uncapable of producing ATP, but also generate excessive amounts of ____.

Answer 22

reactive oxygen (ROS)

[ROS causes cell damage and senescence by oxidating various cellular proteins, lipids and DNA.]

Question 23

What are the spatial locations of iAAA, mAAA, and Lon?

Answer 23

iAAA = outer face of inner membrane
mAAA = inner face of inner membrane
Lon = inside inner membrane space

Question 24

Mutation in mAAA:

Answer 24

Hereditary spastic paraplegia

[cannot control dysfunctional proteins, neurons are the first to go]