Question

Correct sequence in electron acceptors in ATP synthesis is
(A)Cyt a, a3, b, c
(B)Cyt b, c, a, a3
(C)Cyt c, b, a, a3
(D)Cyt b, c, a3, a

Answer 1

Hint: ATP synthesis is carried by the process known as electron transport chain. It is a group of proteins that convey electrons through a membrane within the mitochondria to form a gradient of protons that leads to the formation of adenosine triphosphate (ATP).

Complete answer:
1.First step in the electron transfer chain electrons proceeds with a series of proteins to make a force for the movement of hydrogen ions and protons through the mitochondrial membrane.
2.The electrons start reactions in Complex I then in Complex II goes on to Complex III and cytochrome c through coenzyme Q, and the end to Complex IV.
3.The NADH has two electrons transferred to ubiquinone (Q) in Complex I (NADH dehydrogenase) and it gives 4 hydrogen ions in the intermediate space. Next, Complex II (succinate dehydrogenase) another electron carrier and coenzyme that succinate is oxidized into fumarate and leads FAD reduced into FADH2 and it is reoxidized, donating electrons to Q.
4.Complex III ( cytochrome c reductase) Q cycle occurs and interaction between Q and cytochromes and molecules consists of iron, to continue the transfer of electrons. In complex III another hydrogen ion is released into the cytosol.
Complex IV (cytochrome c oxidase) is the end complex that transfers four protons across the membrane that develops ATP at the end.
5.These electrons which release into intermediate spaces generate the proton gradient, F1F0 ATP synthase, as Complex V, generates the ATP.

Hence, the correct answer is option(C)

Note: These complexes are embedded in phospholipid membrane. They contain metal ions like iron to help with proton expulsion into the intermembrane space. The complexes show conformational changes to allow openings for the transmembrane movement of protons.