Oxidative Phosphorylation

Question 1

Substrate level phosphorylation

Answer 1

Any chemical reaction that directly uses exothermic reaction to drive phosphorylation of ADP. Generally an unstable molecule passes p to ADP

Question 2

Example of substrate level phosphorylation in glycolysis

Answer 2

1,3-biophosphoglycerate to 3-phosphoglyerate

Question 3

Example of substrate level phosphorylation in citric acid cycle

Answer 3

Succinyl coA to succinate, GDP to GTP but relies on hydrolysis of thioester bond rather than high energy phosphate

Question 4

How does oxidative phosphorylation differ from substrate-level?

Answer 4

Uses REDOX to drive phosphorylation and not a strict 1:1 ratio

Question 5

Sources of reduced co-enzymes

Answer 5

1. FA oxidation (doesn’t produce ATP)
2. AA oxidation
3. Citric acid cycle

Question 6

Shuttles

Answer 6

Systems that transfer reducing power to NAD/FAD in mitochondria

Question 7

Outline the malate-aspartate shuttle

Answer 7

1. Malate dehydrogenase in the cytosol can take oxoloacetate and convert it to malate (opposite of citric acid cycle)
2. This uses NADH -> NAD
3. Malate then has reducing power from NADH
4. Transported to inner MM where malate dehydrogenase converts back to oxoloacetate
5. This generates NADH

Question 8

NADH is worth ____ ATP

Answer 8

2.5

Question 9

FADH2 is worth ____ ATP

Answer 9

1.5

Question 10

Outline the glycerol -3-P shuttle

Answer 10

1. Dihydroxyacetponephosphate can take the reducing power from NADH and become glycerol-3-P
2. Using glycerol-3-P dehydrogenase
3. Glycerol-3-P transferred into IMS
4. Another version of glycerol-3-P-dehydrogenase converts this to dihydroxyacetone phosphate
5. This converts FAD to FADH2 (bound to enzyme)

Question 11

Which shuttle is more efficient?

Answer 11

Malate-aspartate however both are used in unison to allow faster regeneration of NAD