Question

imagine an organism with mutations in complexes i, iii, and iv that prevent pumping of hydrogen ions into the intermembrane space but still allow electrons to pass through the electron - transport chain. which of the following is the most likely consequence of these mutations?

• nadh and fadh₂ will not donate new electrons to the electron - transport chain.
• oxygen will not accept electrons and combine with 2 h⁺ to form water at the end of the electron - transport chain.
• the mobile electron carriers q and cyt c will no longer pass electrons through the electron - transport chain.
• atp synthase will not convert adp to atp

Explanation:

In the electron - transport chain, complexes I, III, and IV are involved in pumping hydrogen ions into the intermembrane space and also in the transfer of electrons. If there are mutations in these complexes that prevent hydrogen - ion pumping but allow electron passage, oxygen is still the final electron acceptor at the end of the electron - transport chain. NADH and FADH₂ will still donate electrons to the chain. The mobile electron carriers Q and Cyt c will still pass electrons through the chain. However, ATP synthase uses the proton - motive force generated by hydrogen - ion pumping to convert ADP to ATP. Without hydrogen - ion pumping, ATP synthase will not convert ADP to ATP.

Answer:

ATP synthase will not convert ADP to ATP