Question

Describe the organization of protein complexes within the cristae. explain how the complexes are involved in atp production.

Answer 1

The organization of protein complexes within the cristae is important for ATP production. The electron transport chain and ATP synthase work together to generate ATP in the cristae.

Step-by-step explanation:

The organization of protein complexes within the cristae plays a crucial role in ATP production. The cristae are the folded inner membrane structures found in mitochondria. The electron transport chain (ETC) and ATP synthase are located within the cristae and work together to generate ATP.

In the ETC, protein complexes I, III, and IV pump protons (H+) from the mitochondrial matrix to the intermembrane space, creating an electrochemical gradient. This gradient drives the synthesis of ATP by ATP synthase, which is located in the cristae membrane. ATP synthase harnesses the flow of protons back into the matrix to generate ATP.

The complex III transfers electrons from complex I or II to complex IV via a mobile transfer molecule called coenzyme Q (Q). Similarly, complex IV transfers electrons to complex IV via a mobile transfer molecule called cytochrome c (Cyt c).

Answer 2

The protein complexes in the cristae that contribute to the H+ gradient (electromotive force) across the cristae membrane include; complexes I (NADH/ubiquinone oxidoreductase), II (succinate dehydrogenase), III (cytochrome c reductase) and IV (cytochrome c oxidase).

Complex I feeds an electron from NADH to a quinol molecule ( concomitantly pumping four protons from the matrix into the crista lumen). Complex III transfers the electron from quinol to cytochrome C (concomitantly pumping one proton). Complex IV transfers the electron from cytochrome c to an oxygen molecule (concomitantly forming a water molecule and pumps four protons).

This H+ gradient is then harnessed by ATP synthase to form ATP by phosphorylating ADP.

NADH+H+ → Complex I → Q → Complex III → cytochrome c → Complex IV → H2O

↑

Complex II

↑

Succinate