Question

The process of ATP synthase enzyme is that:
A. It uses energy to move ions against their concentration gradient by removing a phosphate group from ATP.
B. It uses the power of ions moving against their concentration gradient to add a phosphate group to ADP.
C. It uses the power of ions moving down their concentration gradient to add a phosphate group to ADP.
D. It uses the power of ions moving against their concentration gradient to remove a phosphate group from ATP.
E. It uses the power of ions moving down their concentration gradient to remove a phosphate group from ATP.

Answer 1

Hint: ATP synthesis takes place by in mitochondria. This reaction is catalyzed by ATP synthase. ATP synthase is present on the inner mitochondrial membrane. ADP has two phosphate groups in its structure and ATP has three phosphate groups in its structure.

Complete answer: ATP synthase is a huge molecular complex, having molecular weight greater than 500,000 Daltons.
The major function of ATP synthase is to move the protons ($H^+$) down their concentration gradient and accept the terminal electron by using ATP and as a result, ATP is produced from ADP. ADP needs a phosphate group to form ATP.
This newly synthesized ATP gives and stores energy.
The reaction that takes place is given below:
ADP + P_i + 3H⁺_outside  ATP + H₂O + 3H⁺_inside

Thus, the correct answer is option C. It uses the power of ions moving down their concentration gradient to add a phosphate group to ADP.

Note: ATP synthase is made up of two protein molecules – the F1 sector and the F0 sector. F1 sector is situated in the mitochondrial matrix and soluble in nature.
The F0 factor is embedded in the inner mitochondrial membrane.
ATP synthase is made up of three molecules of subunit α and β, and one molecule of subunit γ, δ, and ε.