CELLULAR RESPIRATION Flashcards
How much net ATP would be produced if three molecules of glucose were used during anaerobic cellular respiration?
6 net ATP would be produced if three molecules of glucose were used during anaerobic cellular respiration.
In an anaerobic environment, only glycolysis can occur. This process produces a net of 2 ATP per glucose, so three glucose molecules would produce 6 ATP total.
A mutation in hemoglobin is identified that decreases the degree of cooperativity of binding of oxygen to nH = 1.4 (for normal hemoglobin, nH = 2.8).
What is true of this mutant form of hemoglobin?
The mutant form of hemoglobin with decreased cooperativity would release oxygen over a larger range of partial pressures of oxygen. The greater the degree of cooperativity of hemoglobin, the more concerted the oxygen binding and release from hemoglobin. The quantity of oxygen that can be carried by hemoglobin is unlikely to change given four oxygen binding sites still exist per hemoglobin and there is no information presented here to explain why this would have changed. Myoglobin, with only a single oxygen binding site, does not display cooperativity (nH = 1). Therefore this mutant form of hemoglobin still maintains a greater degree of cooperativity than myoglobin.
Antimycin is used as a piscicide (fish poison) because it inhibits Complex III of the electron transport chain.
Blocking the flow of electrons through Complex III will produce which of the following effects?
I. Complex I (NADH dehydrogenase) will persist in a reduced state.
II. Complex IV (cytochrome C oxidase) will persist in a reduced state.
III. Oxygen consumption will be decreased.
Reduced electron carriers like NADH and FADH2 transport electrons from the reactions of glycolysis, the pyruvate dehydrogenase complex, and the Krebs cycle to the electron transport chain. Electrons are then relayed through the various proteins of the chain and finally to oxygen, which is reduced to water. Inhibiting any part of the electron transport chain will halt the transfer of electrons. Statement I is true: Blocking electron transport at Complex III will result in a build-up of electrons at proteins earlier in the chain. Because these earlier proteins, including Complex I, cannot pass their electrons off, they will persist in the reduced state (“Gain of Electrons is a Reduction”). Statement II, however, is false: Proteins later in the chain can release their electrons, but cannot replenish them. These later proteins, including Complex IV, will persist in the oxidized state (“Loss of Electrons is an Oxidation”). Electrons meeting a roadblock at Complex III will never reach oxygen. Thus, oxygen consumption (reduction) will be decreased. It is important to note that inhibiting the electron transport chain diminishes the proton gradient and compromises ATP synthesis. This is why antimycin is so toxic to cells.
