Metabolism
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Is fructose fattening?
Objectives
By the end of this exercise you should be able to:
Describe how phosphofructokinase acts as the main regulator of glycolysis.
Describe how phosphofructokinase is about 90% inhibited by normal intracellular concentrations of ATP, and how this inhibition is relieved by 5'AMP; describe how 5'AMP is formed as ADP begins to accumulate in the cell.
Explain the metabolic importance of the inhibition of phosphofructokinase by phosphoenolpyruvate.
Explain the metabolic importance of the inhibition of phosphofructokinase by citrate.
Describe the role of citrate in providing a source of acetyl CoA in the cytosol for fatty acid synthesis and explain how it is that citrate does not leave the mitochondrion unless there is enough to maintain full activity of the citric acid cycle. Explain how citrate, which is a symmetrical molecule, behave asymmetrically.
Explain the metabolic importance of the sequence of reactions between oxaloacetate and pyruvate in the cytosol.
Explain how it is that fructose metabolism is not controlled by the need for ATP synthesis or cytosolic citrate, and how it is that a high fructose intake will lead to increased fatty acid synthesis.