Which of the statenents about the evolution of the citric acid cycle are consist

Question

Which of the statenents about the evolution of the citric acid cycle are consistent with existing knowlege? A reductive citric acid cycle can replenish oxidized cofactors such as NADH Although some organisms do not use the citric acid cycle under anaerobic conditions, they use a reductive pathway similar to the citric acid cycle to generate some larger molecules. The citric acid cycle may have evolved from two biosynthetic pathways in early life forms. Early organisms may have lacked the enzyme -ketoglutarate dehydrogenase. mThe citric acid cycle may have originated from two pathways-a reductive pathway and an oxidative pathway

Explanation / Answer

First option is incorrect, rest all are correct and consistent with the existing knowledge.

The anaplerotic reactions replenish citric acid cycle INTERMEDIATES. However, it cannot replenish oxidized cofactors such as NADH.

Reductive citric acid cycle reverses the reaction of oxidative cycle and can generate larger molecule. Hence, it may have generated from two pathways an oxidative and a reductive. Further, early organisms may have lacked the enzyme alpha-Ketoglutarate dehydrogenase.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.