Question

O words Question 40 10 pts Most of the ATP from metabolism is formed during the Respiratory Chain or oxidative phosphorylation. • Follow the path of electrons and protons from NADH (or FADH2) through oxidative phosphorylation. Be sure to highlight the cytochromes, starting substrates, enzymes, and final product(s). (6 points) Cyanide is a competitive inhibitor of cytochrome coxidase. What does 'competitive inhibitor' mean? Describe an effect of cyanide exposure to oxidative phosphorylation. Explain the rationale behind treating cyanide poisoning with pure 02.(4 points) HTML Editore BI VA - A - I E x , SE . DON GOV DTT 12ptParagra

Answer 1

1. ETC starts with complex I one in which 4 H+ ions are pumped through mitochindrial martix to intermembrane space. There is a reduction of NADH to NAD+ by NADH dehydrogenase

Follewd by the reduction of FADH2 to FAD at complex II by succinate dehydrogenase Coenzyme Q picks electrons from both the complexes (I and II).

4 H+ ions are again pumped to intermembrane space by complex III by the enzyme ubiquinone : cytochrome oxidoreductase. Cytochrome C, electron carrier, transports the electron to complex IV. There is flux of 2 H+ ions from matrix to intermembrane leading to formation of water by cytochrome oxidase.

Complex V, also known as ATP synthase pumps electrons form intermembrane space to matrix and there is formation of ATP by ADP

44 44+ cytochromec QH+ TH+ payme de pe pumzused kepe ema.) eyes deuruuuuuuusss, fulle flow - FAOH KAO I 24 + 02 H₂O Inter men space te ? ? inne mitoch. membe (NADHT) Lt NAO mitochondrial matrix Electron transport ADP + Pi HT Chainsport Ате ATP synthase

So finally the end products are water and ATP.

2. Competive inhibitors mimic the substrate and bind to the active site of enzyme thereby prevents the binding of actual substrate thus inhibits the reaction.

Cyanide is a toxic compound and it inhibits cellular oxygen metabolism and eneey production. It reversibly binds to Fe3+ ions in cytochrome oxidase a3 in respiratory ETC and donot carry electron to produce water. It blocks the passage of electrons and halt the productiom of ATP by ATP synthatasw which depends on the proton gradient to phosphorylate ADT to ATP.

3. Oxygen treatment is given to provode artificial respiration. It has been studied that rabits, cats, dogs with lethal dose of cyanide can be saved with oxygen. Inhaling pure oxygen increases the heamoglobin saturation on bkood and helps in augumentation of small proportion of cellular respiration which is independent of cytochrome oxidase, prolonging the life of patient enough for detoxification.