Which enzyme catalyzes the conversion of ADP and inorganic phosphate to ATP?

Which enzyme catalyzes the conversion of ADP and inorganic phosphate to ATP?

• A. DNA polymerase
• B. Hexokinase
• C. Carbonic anhydrase
• D. ATP synthase

Answer: (D)

The main idea is how energy stored in a proton gradient is converted into chemical energy stored in ATP. ATP synthase uses the flow of protons across a membrane to drive the formation of ATP from ADP and inorganic phosphate. Its F0 domain forms a proton channel while the F1 catalytic head uses the energy from rotor rotation to bring ADP and Pi together and catalyze the bond formation, producing ATP. This mechanism, known as chemiosmotic coupling, is central to oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts. Other enzymes listed have different roles: one transfers a phosphate to glucose using ATP, another helps form DNA, and another speeds up CO2 hydration. Thus, ATP synthase is the enzyme that makes ATP from ADP and Pi.

The main idea is how energy stored in a proton gradient is converted into chemical energy stored in ATP. ATP synthase uses the flow of protons across a membrane to drive the formation of ATP from ADP and inorganic phosphate. Its F0 domain forms a proton channel while the F1 catalytic head uses the energy from rotor rotation to bring ADP and Pi together and catalyze the bond formation, producing ATP. This mechanism, known as chemiosmotic coupling, is central to oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts. Other enzymes listed have different roles: one transfers a phosphate to glucose using ATP, another helps form DNA, and another speeds up CO2 hydration. Thus, ATP synthase is the enzyme that makes ATP from ADP and Pi.