How is ATP Made by an Acetogen During CO₂ Fixation

Question

How is ATP made by an acetogen during CO₂ fixation?
A) Electrons from metal cofactors energize the electron transport chain and drive the proton motive force to activate ATP synthase.
B) Substrate-level phosphorylation of ADP occurs when coenzyme A is removed from acetyl-CoA.
C) It is made using substrate level phosphorylation and an ion motive force.
D) Acetyl CoA is produced from acetate and ATP is produced through substrate level phosphorylation.

Accepted Answer

Acetogens fix CO₂ by generating acetyl-CoA from CO₂ and other compounds such as hydrogen or formate using the Wood-Ljungdahl pathway. During this process, ATP is synthesized via substrate-level phosphorylation and an ion motive force. The ion motive force is generated by the electron transport chain, which is energized by electrons from metal cofactors such as iron-sulfur clusters. The proton motive force generated by the electron transport chain drives ATP synthase to produce ATP. Therefore, both substrate-level phosphorylation and an ion motive force contribute to ATP synthesis during CO₂ fixation by acetogens.