1. Please refer the figure below, which shows how the citric acid cycle plays a
ID: 216792 • Letter: 1
Question
1. Please refer the figure below, which shows how the citric acid cycle plays a role in the biosynthesis of metabolic intermediates for other pathways. The conversion of pyruvate to oxaloacetate is an anaplerotic (or anapleurotic) reaction. Pyruvate Amino acids Fatty acids Acetyl-CoA Glucose Oxaloacetate Cholesterol Asparate Malate Citrate Tyrosine Fumarate Isocitrate Succinate Succinyl-CoA a-Ketoglutarate Porphyrins Amino acids Methionine Valine Odd-chain fatty acids a. (3 pts.) Define the term "anaplerotic reaction." b. (2 pts.) The enzyme catalyzes this reaction. c. (3 pts.) Explain what induces the need for this anaplerotic reaction.Explanation / Answer
A. Anaplerotic reaction are chemical reactions that form inermediate of a metabolic pathway. Example of suh are found in the citric acid cycle . In normal function of this cycle is respiration , concentration of TCA intermediate remain constant; however ,many biosynthetic reaction also use these molecules as a substrate.
B. The enzyme pyruvate carboxilase catalyze this reaction.
C. In condition for high carbohydrate diet pyruvate carboxylase expression is increased in beta cells to enhance pyruvate cycling activity in response to chronically elevvated level of glucose.
D. Not sure about this statement.
2.
A. In order to glycolysis to continue there must be adequate amount of NAD available to accept hydrogen atom. Therefore the NADH produced in glycolysis must become oxidised by donating its electron to another molecule.
When oxygen is not available in sufficient amount the NADH produced in glycolysis is oxidised in cytoplasm by donating its electrons to pyruvic acid. This result in reformation of NAD and the addition of two hydrogen atoms to pyruvic acid, which is thus reduced. This addition of two hydrogen atoms to pyruvic acid produces lactic acid.
B. Dichloroacetate has been shown to reduce blood lactate level effectively in various condition.it is an activator of the pyruvate degydrogenase complex.
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