Question

Which of the following would be most detrimental for cellular respiration? That is, which one would result in the greatest reduction in the number of ATP molecules being generated?

Select one:

a. A strong reducing agent which is only active in the inter-membrane space of mitochondria

b. A strong oxidizing agent which is only active in the mitochondrial matrix

c. A strong reducing agent which can enter the cytoplasm but not the mitochondrial matrix

d. A strong oxidizing agent which enters the cytoplasm but not the mitochondrial matrix

answer is B... why?

Answer 1

• The mechanism of oxidative phosphorylation occurs in mitochondria of live cells.
• Electrons are transported across various components of electron transport chain (ETC), resulting in series of oxidation-reduction reactions within the membrane bound complexes in mitochondria (complex I, II, III, IV).
• NADH and FADH2 are electron donors, their oxidation creates high concentration energy from electrons.
• This energy is used to pump proton from matrix to inter membrane space. Flow of protons creates and electrochemical gradient, which is used to generate ATP.
• In the mitochondrial matrix, electrons are shuttled within different carrier molecules or electron transporters.
• If these electron carriers come in vicinity or contact to oxygen or oxidizing agents, electrons may be transferred to oxygen molecule.

Answer: b.

As a strong oxidizing agent will accept electrons from electron tranporter and prevent electron flow in mitochondrial matrix, preventing generation pf proton motive force and ATP generation.