22. Mitochondrial details

Question 1

Oxidative phosphorylation proteins are located in the .. of the …

Answer 1

IM of the mito

Question 2

ATP synthetase is which protein on the membrane? (1-5)

Question 3

ATP is synthesized in 1 of mito’s, with H+ gradient in 2. However, most ATP
is needed in 3. They need to be shuttled out by specific 4

Answer 3

1 Matrix
2. IMS
3. Cytosol
4. ATP antiporter (VDAC)

Question 4

Anti- vs symporter?

Answer 4

Antiporter: one thing goes out, one thing goes in (ADP out, ATP in)
Symporter: both out/in

Question 5

There is also another symporter located at the ATP site, what does it do?

Answer 5

• Another symporter transports phosphate inside matrix together with protein. Phosphate needed to make ATP.

Question 6

Transport of reducing equivalents (NADH) from 1 into 2 by 3 at the cost of 4

Answer 6

1 cytoplasm
2. mito
3. glycerophosphate shuttle.
4 Loss of 1 ATP: NADHc(2.5) -> FADHm (1.5)

Question 7

Where is the glycerophosphate shuttle located? What is useful about this?

Answer 7

Glycerophosphate shuttle in mito: happens in intermembrane space. Not matrix of mito’s.

Fadh released very close to IMM. Will donate energy from NADH, now FADH directly to co-enzyme Q (CoQ)

Question 8

Does every NADH get shuttled from cytoplasm into mito by glycerophosphate shuttle? Explain

Answer 8

this does not happen in every tissue like this. This one is very specific. Only for skeletal muscle and brain.

Question 9

How much H+ = 1 ATP?

Answer 9

4 H+ = 1 ATP

Question 10

When NADH (not FADH) is released to ox phos, this will come to complex A of ox phos, then to B (which is C), then to D , …

Answer 10

A 1
B 2
C (co enzyme Q)
D 3

Question 11

Cost of glycerophosphate shuttle?

Answer 11

NADH -> FADH, so 2.5-1.5 = 1 ATP

Question 12

What is useful about cristae?

Answer 12

seems like the complexes are in here, with specific efficient locations. Small location, high accumulation H+.

Question 13

In what processes does FADH production happen?

Answer 13

FADH: production in

• TCA cycle (succinate -> fumarate. Succinate dehydrogenase, is also in complex 2)
• glycero-P shuttle
• beta-oxidation.

Question 14

Why will FADH in ox phos lead to less energy than NADH?

Answer 14

FADH always donates energy to Co-enzyme Q! Never complex 1. This is why FADH will lead to less ATP production than NADH. Protons are not pushed out in this case by complex 1.

Question 15

Which complexes push out protons?

Answer 15

1,3,5

Question 16

What other shuttle system is there (not in skeletal muscle and brain)? Where is it highly active?

Answer 16

more complex shuttle system in tissues other than skeletal muscle and brain: Malate-aspartate shuttle

Active in
- Liver
- Kidney
- Heart
- Adipose

Question 17

What happens with the malate-aspartate shuttle (use meta map)?

Everytime a 1 enters the mito, 2 is shuttled outside
Everytime an 3 leaves the mito, a 4 enters
They are reused in the cycle.

Answer 17

1. Cytosol: OAA > Malate
2. Malate enters mito
3. Malate > OAA (+1NADHm: 2.5 ATP)
4. OAA > aspartate
5. Aspartate leaves mito into cytosol
6. Cytosol: Aspartate > OAA
7. Cytosol: OAA > aspartate

1 Malate
2 alfa-keto glutarate

3. Aspartate
4. glutamate

Question 18

What is the main difference between the two shuttles?

Answer 18

Malate- asp: NADHc = NADHm
Glyceroph: NADHc = FADHm

1 more ATP remained at malate-asp
1 less ATP at glyceroph

1 ATP difference

Question 19

Why is malate asp not used in brain if it is so efficient?

Answer 19

= constant rate of heat generation. Less ATP obtained with glyc-3-p shuttle, but constant heat, which is important in these tissues.

Question 20

Difference full glucose ox with malate asp vs glyceroph shuttle?

Answer 20

Full glucose ox = 30 ATP
Malate/asp = 32 ATP

2 NADHc that needs to enter mito -> 3 ATP (2 FADH) (bc 2x pyruvate: OAA > malate, then malate outside mito)
2 NADHc that needs to enter mito -> 5 ATP (2 NADH)

Question 21

Gluconeogenesis: pyruvate > OAA > malate out of mito into PEP.
There is another pathway used when there is a lot of pyruvate. Lot of lactate
Explain

Answer 21

Lactate leads to NADH in the cytosol. Lactate -> pyruvatec > pyruvate m > OAA.
OAA is then directly converted into PEPm > Pepc. No NADHm used, some energy is saved.

Question 22

Choice for gluconeogenesis pathway depends on ..?

Answer 22

• Amount mito NADH (lot = original pathway)
• Pyruvate in cyto (lot = NADH-saving pathway)

Question 23

In the liver, gl-6-p can be converted into glucose. When in the cytosol, there would be competition with the enzyme that catabolizes glucose -> gl-6-p. Therefore …

Answer 23

Therefore, enzyme that converts gl-6-p to glucose is present in the ER. When liver wants to release glucose, there is endocytosis: glucose will immediately go into blood circulation.

Compartments important!

Question 24

ATP transport mito’s: from 1 to 2, also here certain enzymes (hexo/glucokinase, glycerolkinase) they are very close to the 3. Immediately use ATP for glucose trapping

Answer 24

1 OM
2 IM
3 ATP transporter

Question 25

Alternative functions:

Citrulline (aa) not only used for protein synthesis, but also in urea cycle.

Citrulline controls…
1
2

Which protein can be converted into citrulline?

Answer 25

1. Gene expression
2. Immune system often attacks citrullinated proteins

Arginine

Question 26

1 and 2 intermediates do not only function as biochemical intermediates. They have effect on long and healthy life

Answer 26

1 Succinate
2 alfa-ketoglutarate

Question 27

 Which of these substances yields 14 ATP upon complete oxidation? (A) alanine (B) pyruvic acid (C) lactic acid (D) acetic acid.

Answer 27

(C) lactic acid

Alanine: 12.5 + 2.5-2 = 13 ATP
Pyruvic acid: 12.5 ATP
Lactic acid: 1.5 + 2.5 + 10 = 14 ATP
Acetic acid: is apparently a fatty acid.
Acetate -> Acetyl-coA = -2 ATP (ATP -> AMP) + 10 ATP = 8 ATP yield.

Acetate is a fatty acid (SCFA C2) You have to charge fatty acids to oxidize them (add a CoA, cost = 2 ATP). Acetate will transform into acetyl-CoA. Just like propionate is transformed into succinyl-CoA.

Question 28

 What is the difference in ATP yield upon complete oxidation of di-hydroxyacetone phosphate and phospho-enol pyruvate?

Answer 28

16 ATP vs 13.5 = 2.5 ATP