Question

Identify the membrane across which the proton gradients causes ATP synthesis in a typical eukaryotic cell.

• A. Plasma membrane
• B. Mitochondrial inner membrane
• C. Mitochondrial outer membrane
• D. Nuclear membrane

Answer 1

Answer: (B)

Mitochondrial inner membrane

The mitochondrial inner membrane is the site of the electron transport chain, an important step in aerobic respiration. $H^{+}$ ions build up in the space between the inner membrane and outer membrane to create a proton potential that helps power the ATP formation. This space is called as the inter-membrane space.

The mitochondrial inner membrane is made primarily of a phospholipid bilayer, just like the cell membrane. Embedded in this bilayer are various proteins that serve to carry out the electron transport chain. The membrane has folds called as cristae that increase it's surface area.