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4 Cards in this Set
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Cell respiration of proteins:
When are proteins used to generate ATP’s? |
When more protein is ingested than is needed to replace tissue protein, the amino acids are oxidized for energy or converted to fat.
In other energy sources {carbohydrates and fats} are inadequate, the mitochondria can break down these surplus amino acids in the Krebs cycle and electron transport chain to generate ATP’s. |
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Explain how amino acids are used to generate ATP’s.
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Before amino acids can be oxidized to generate ATP’s, they must be deaminated.
In this process the amino group is removed and picks up a H to form NH3. The NH3 combines with CO2 to form urea - most of which is secreted in the urine. The resulting molecule is converted to a Keto acid which can then be converted to pyruvic acid, acetyl C0-A, or one of the keto acids of the Krebs cycle. In this way ATP’s are generated by the Krebs cycle and the electron transport chain. |
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What is the ATP harvest for the respiration of an amino acid?
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Since not all amino acids enter the Krebs cycle at the same point, the ATP yield varies.
However the average ATP yield per gram is comparable to that of carbohydrate respiration. |
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3 factors that make the respiration of proteins an impractical source of quick energy.
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1. Proteins are more difficult to break apart than complex carbohydrates and fats.
2. One of the by products of protein respiration, NH3, is a toxin that can damage cells. 3. Proteins form the most important structural and functional components of the cell. So extensive protein respiration threatens homeostasis at the cellular and system levels. |
