Question

The electrons released by the FAD during glycerol phosphate shuttle is transferred to:
A. NAD
B. Coenzyme Q
C. Succinate
D. DHAP

Answer 1

The glycerol phosphate shuttle takes place to oxidise the NADH produced during glycolysis through oxidative phosphorylation to produce ATP.

Complete answer:
In the first part of the shuttle the NADH that is produced during the process of glycolysis is converted to NAD+ by giving up one of its protons. The oxidation of NADH is carried out by the simultaneous reduction of dihydroxyacetone phosphate (DHAP) to glycerol phosphate. This reaction takes place in the cytoplasm of the cell.
Following this the glycerol phosphate moves to the intermembrane space of the mitochondria. Once it enters into the intermembrane space it is oxidised back to DHAP by the action of the enzyme glycerol phosphate dehydrogenase which is a membrane bound enzyme. The enzyme consists of a bound FAD that after accepting two protons and electrons gets converted to $FADH_{2}$. The $FADH_{2}$ then gives up two protons to coenzyme Q also known as ubiquinone which then moves along the inner mitochondrial membrane to transfer the electrons to complex III of the electron transport chain. Finally it leads to the formation of 1.5 ATP molecules per molecule of NADH as the complex I is bypassed in this shuttle.

Hence, the correct answer is option (B)

Note: The glycerol phosphate shuttle mainly takes place in the skeletal muscle and brain tissue and is the most important process occurring in these tissues which is involved in maintaining the cytoplasmic redox balance which in turn is very important in maintaining cellular metabolism.