There are two different shuttles for the transport of NADH from cytoso...
The two shuttles operating between mitochondria and cytosol are malate shuttle and glycerol 3 phosphate shuttle. Among these two, malate shuttle generate more energy per glycolytic cycle. Glycolate and glutamate shuttles do not exist. In glycerol 3 phosphate shuttle, Dihydroxyacetone phosphate (DHAP) is converted to glycerol 3 phosphate by oxidizing NADH to NAD+ in cytosol. However, when glycerol 3 phosphate is converted back to DHAP by mitochondrial glycerol 3 phosphate dehydrogenase, FAD is reduced to FADH instead of NADH and we know, that one molecule of NADH gives 2.5 ATP and 1 molecule of FADH gives 1.5 ATP. Therefore, via glycerol 3 phosphate shuttle, 1 molecule of NADH produced from glycolysis in cytoplasm is transported to mitochondria in the form of FADH which gives 1.5 ATP unlike NADH which gives 2.5 ATP. Therefore via glycerol 3 phosphate shuttle, less number of ATP are produced from glycolysis compared to malate aspartate shuttle. In malate aspartate shuttle, NADH produced in cytoplasm from glycolysis is transported in the mitochondria for oxidation in the form of NADH only.
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There are two different shuttles for the transport of NADH from cytoso...
Explanation:
The transport of NADH from cytosol to mitochondria is necessary for the continuation of glycolysis and the production of ATP. There are two different shuttles that carry NADH from the cytosol to the mitochondria: the glycerol 3-phosphate shuttle and the malate-aspartate shuttle. The net ATP produced from glycolysis depends on which shuttle is used.
Glycerol 3-phosphate shuttle:
- NADH yields 1.5 ATP in the mitochondria
- 2 NADH molecules are produced in the cytosol during glycolysis
- Therefore, the net yield of ATP is 3 ATP per glucose molecule
Malate-aspartate shuttle:
- NADH yields 2.5 ATP in the mitochondria
- 2 NADH molecules are produced in the cytosol during glycolysis
- Therefore, the net yield of ATP is 5 ATP per glucose molecule
Thus, the malate-aspartate shuttle yields higher ATP per glycolytic pathway, making option C the correct answer.
Glycolate shuttle and Glutamate shuttle:
- The glycolate shuttle is found in plants and bacteria, and the glutamate shuttle is found in prokaryotes.
- They are not involved in the transport of NADH from cytosol to mitochondria in eukaryotic cells.
- Therefore, they are not relevant to this question.