Term
| Can HK phosphorylate fructose? |
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Definition
| Yes, but the Km is very high |
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Term
| Effects of fructose consumption |
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Definition
| rapid depletion of inorganic phosphate and energy sources; elevated levels of uric acid; lactic acidosis |
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Term
| Why does fructose cause a rapid depletion of inorganic phosphate and energy sources? |
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Definition
| Fructokinase is very active and fructose transport into liver is very rapid, causing F1P to accumulate. ATP is converted to ADP by fructokinase and triose kinase; Pi is used to convert ADP to ATP by oxidative phosphorylation, leading to Pi depletion (trapped in F1P) |
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Term
| Why does fructose cause elevated levels of uric acid? |
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Definition
| Uric acid is the end product of purine metabolism; a drop in Pi, and increase in AMP levels (2 ADP yield ATP and AMP), trigger purine degradation |
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Term
| Why does fructose cause Lactic acidosis |
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Definition
| to allow glycolysis to keep up |
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Term
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Definition
Aldolase B is found primarily in liver and kidney. Aldolase A & C are in other tissues. Liver still splits F1,6BP with residual B activity and low levels of A form of aldolase (A form will not split F1P). Enzyme has <15% activity.
F1P accumulates due to speed of fructokinase reaction |
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