Question

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9. The diagrams below depict Complex III of the mitochondrial respiratory chain. Use them to draw out the sequence of events that constitute the mitochondrial cycle. Indicate the path of travel of electrons and protons through Complex III, as well as correct stoichiometry of each. Also include the names of all mobile and fixed electron carriers associated with the O-cycle and Complex II. Use the diagram on the left to depict events following binding of the first OH molecule to Complex III. Use the diagram on the right to depict events following binding of the second QH2 molecule to Complex III First QH: Second QH:

Answer 1

First QH2 Second QH₂ QH CYTOPLASM (P-foce) ( Q H₂ e -fe-s+ Cyt a, > e bu - CYTOPLASH site se'fe-sreyt QИ. D.siteli Q pool (A pool.) e ۔ > MATRIX (N-have) MATRIX فجر دقی An site kebH complex- complea-

علم de omplee segurar Cines Complementation, content n Componentes 'chino mo one n HH ة وكله ( Complex - I a . Complex - P a 7 Complea - In contain & Compounds je le-s and Cytochrome b as main components along with mobile caraien. Cytochromo si Cezt cs) 1- Diffusion of one Ubiquinol (@JH) to Qp binding site adjacent to the Te-s (iron- Suffer Protein). 2 - Tavo electrones transformed from QHz. (QH. Q released 3. One of them to re-s protein followed by to cyt-ci. 4. Other e transferred to Cytochrome-bi CL- Light chain) followed by - to Cytochrome 6H (It-Heary chain). 5. Then Ubiquinone @ binds to ba at Qn site,o es from reduced by transten to a to form Semiubiquinone & ica 6- Then a Second QHz vacidised again at Ap site and subesequent steps follows as above mentioned. 2 Ht also released during QHz dissociation.' 7. Similarly the 2nd e- from reduced by transferred to ubiseriquinone (@) to form ubiquino! (@H2). During this process 24t require onm tranchen 190 none transhe mom du les

FIXED CARRIER OF COMPLEX-III

Fe-S: Iron Sulfur protein

Cytochrome bL

Cytochromr bH

MOBILE ELECTRONE CARRIER

QH2- UBIQUINOL

Q-: SEMIUBIQUINONE

Q: UBIQUINONE