Question

Order the following steps in the Q cycle. The question is graded as ALL OR NOTHING, so all steps must be in the correct order for credit.

1. A second QH2 molecule binds in the QP site and is oxidized. One electron ends up on a new cytochrome c, and the other goes to the bL heme.
2. QH2 is released into the membrane.
3. The Q in the QN site is reduced by the electron from heme bN, forming a semiquinone intermediate.
4. The first QH2 is oxidized at the Qp site. One electron ends up on cytochrome c, and the other goes to the bL heme.
5. The oxidized Q molecule moves from Qp to QN, stimulating electron transfer from heme bL to heme bN.
6. The electron from heme bL moves to heme bH and is used to reduce the semiquinone in the QN site.
7. The Q molecule is released into the membrane.

Answer 1

4, 5, 3, 1, 7, 6, 2

Step-by-step explanation:

In This Mechanism of Q Cycle(Quinol Cycle);

The Q cycle (quinol) describes a series of reactions that describe how the sequential oxidation and reduction of the lipophilic electron carrier, Coenzyme Q10 (CoQ10), between the ubiquinol and ubiquinone forms, can result in the net movement of protons across a lipid bilayer (in the case of the mitochondria, the inner mitochondrial membrane).

The first QH2 is oxidized at the Qp site. One electron ends up on cytochrome c, and the other goes to the bL heme.

The oxidized Q molecule moves from Qp to QN, stimulating electron transfer from heme bL to heme bN.

The Q in the QN site is reduced by the electron from heme bN, forming a semiquinone intermediate.

A second QH2 molecule binds in the QP site and is oxidized. One electron ends up on a new cytochrome c, and the other goes to the bL heme.

The Q molecule is released into the membrane.

The electron from heme bL moves to heme bH and is used to reduce the semiquinone in the QN site.

QH2 is released into the membrane.