Question

Which of the following is required for the ATP synthesis to occur in the cell?
(a) $ { H }^{ + } $ gradient across the membrane
(b) $ { K }^{ + } $ gradient across the membrane
(c) ${ PO }_{ 4 }^{ 3 }$ gradient across the membrane
(d) $ { Ca }^{ 2+ }$ gradient across the membrane

Answer 1

Hint: The gradient established by $ { H }^{ + } $ ions across the mitochondrial membrane is very important for the process of ATP synthesis. Only after the $ { H }^{ + } $ ions pass through the membrane with the help of membrane protein, the conversion of ADP to ATP occurs inside mitochondria.

Complete step by step answer:
A proton gradient is established across the mitochondrial membrane during the ATP synthesis by the electron transport chain (ETC) . This gradient helps in the ATP synthesis. This process uses the energy stored in the form of a $ { H }^{ + } $ ion. This is called chemiosmosis. Thus, the energy released during the ETC is used for pumping of $ { H }^{ + } $ ions across the mitochondrial membrane which results in an electrochemical gradient. Without this, the conversion of ATP can not occur. Therefore, $ { H }^{ + } $ gradient across the membrane is required for the ATP synthesis.
The $ { H }^{ + } $ ions can pass through the membrane only in the presence of a membrane protein called ATP synthase. As it moves with the help of the protein ADP gets converted into ATP. This process of ATP production by the process of chemiosmosis in mitochondria is known as oxidative phosphorylation.

Note: Chemiosmosis of $ { H }^{ + } $ ion across the mitochondrial membrane is a very important step of ATP synthesis inside mitochondria. During this, the free energy from the reactions of ETC is used to pump the hydrogen ions across the membrane. This hydrogen ion generation is essential to provide the energy required for ATP synthesis.