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1MileCrash
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I have been given a bonus question prior to the test.
Compare the end products and total energy yield for glycolysis and respiration with fermentation in muscle cells. What problem does fermentation solve? What problem does fermentation create? What is oxygen debt?
Glycolysis & Respiration differs from Fermentation in many ways. A unique feature of mammalian muscle cells when compared to other types of cells is the ability to switch from Glycolysis & Respiration to Fermentation when circumstances require. Muscle cells will only switch to fermentation when oxygen is scarce because respiration yields much more energy than fermentation. Respiration yields 36 (theoretical) net ATP per glucose molecule, much greater than the yield of fermentation, which is 2 net ATP per glucose molecule.
Glycolysis reduces NAD+ to NADH, but due to the limited amount of NAD+ within the cell, NADH must be "recycled" by being oxidized back into NAD+, which is normally done via an electron transport chain in cellular respiration. However, this process can only work in the presence of oxygen because it is the final electron acceptor of the ETS.
During vigorous activity, the circulatory system cannot keep up with the cellular demands for oxygen. This becomes a problem for glycolysis, as the NADH can no longer be oxidized back into NAD+ through respiration.
Fermentation solves this problem of oxygen deficiency and allows glycolysis to continue. Rather than NADH being reduced by the ETS, NADH and the Pyruvate created by the initial splitting of glucose enter a Redox reaction. The oxidation of NADH recycles it into NAD+, allowing glycolysis to continue; the reduction of pyruvate yields an organic acid known as lactic acid.
However, the problem with fermentation is the accumulation of lactic acid, which interferes with muscle function. After vigorous activity has stopped, the accumulated lactic acid is catabolized into CO2 and water. This process also requires additional oxygen. The amount of additional oxygen needed to catabolize the accumulated lactic acid is termed the oxygen debt.
Compare the end products and total energy yield for glycolysis and respiration with fermentation in muscle cells. What problem does fermentation solve? What problem does fermentation create? What is oxygen debt?
Glycolysis & Respiration differs from Fermentation in many ways. A unique feature of mammalian muscle cells when compared to other types of cells is the ability to switch from Glycolysis & Respiration to Fermentation when circumstances require. Muscle cells will only switch to fermentation when oxygen is scarce because respiration yields much more energy than fermentation. Respiration yields 36 (theoretical) net ATP per glucose molecule, much greater than the yield of fermentation, which is 2 net ATP per glucose molecule.
Glycolysis reduces NAD+ to NADH, but due to the limited amount of NAD+ within the cell, NADH must be "recycled" by being oxidized back into NAD+, which is normally done via an electron transport chain in cellular respiration. However, this process can only work in the presence of oxygen because it is the final electron acceptor of the ETS.
During vigorous activity, the circulatory system cannot keep up with the cellular demands for oxygen. This becomes a problem for glycolysis, as the NADH can no longer be oxidized back into NAD+ through respiration.
Fermentation solves this problem of oxygen deficiency and allows glycolysis to continue. Rather than NADH being reduced by the ETS, NADH and the Pyruvate created by the initial splitting of glucose enter a Redox reaction. The oxidation of NADH recycles it into NAD+, allowing glycolysis to continue; the reduction of pyruvate yields an organic acid known as lactic acid.
However, the problem with fermentation is the accumulation of lactic acid, which interferes with muscle function. After vigorous activity has stopped, the accumulated lactic acid is catabolized into CO2 and water. This process also requires additional oxygen. The amount of additional oxygen needed to catabolize the accumulated lactic acid is termed the oxygen debt.