Metabolism and its Control 2 Flashcards
Conversions of one TCA cycle
- Acetyl-CoA –> CoA + 2 CO2
- 3 NAD+ –> 3 NADH
- FAD –> FADH2
- GDP + Pi –> GTP
How many NADH/FADH2 molecules are there after glycolysis and TCA cycle?
- 10 NADH
- 2 FADH2
Where are all enzymes for the ETC found?
In inner mitochondrial membrane
Equation for oxidation of NADH
NADH + H+ –> NAD+ + 2H+ + 2e-
Which complexes do the 2e- from NADH pass through?
I and III
How many H+ are moved into the intermembrane space by complexes I and III with NADH’s 2e-?
4H+ each
How much ATP is made from each NADH/FADH2?
- NADH = 2.5
- FADH2 = 1.5
How many H+ make 1 ATP?
3
Equation removing e- from ETC
2e- + 2H+ + 1/2O2 –> H2O
What complex catalyses the transfer of e- to molecular oxygen to remove them from ETC?
Complex IV (cytochrome c oxidase)
What can inhibit complex IV?
- Cyanide
- Carbon monoxide
- Azide
Mechanisms to enable reducing equivalents to be transferred from cytosol into mitochondria for the ETC
- Glycerol phosphate shuttle
- Malate/aspartate shuttle
How does the glycerol phosphate shuttle work?
- Cytosolic NADH used to reduce DHAP into glycerol-3-phosphate through cytosolic glycerol-3-phosphate dehydrogenase
- Glycerol-3-phosphate diffuses into mitochondria
- Glycerol-3-phosphate oxidised by mitochondrial glycerol-3-phosphate dehydrogenase into DHAP and FADH2
How does the malate aspartate shuttle work?
- Oxaloacetate reduced into malate by malate dehydrogenase (used NADH)
- Malate diffuses into mitochondria
- Original reaction reversed inside mitochondria by mitochondrial malate dehydrogenase (releases NADH)
- OAA transaminated to aspartate which is transported into the cytosol
- Aspartate converted back to OAA by cytosolic aspartate aminotransferase
How does brown adipose tissue maintain body temperature?
Mitochondria are largely uncoupled, so energy is released as heat instead of ATP
