BMCB 658 Lecture Notes - Lecture 16: Oxaloacetic Acid, Lysine, Decarboxylation

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peachprairie-dog751

19 Aug 2016

School

UNH

Department

Biochemistry, Molecular & Cellular Biology

Course

BMCB 658

Professor

Carrie A.May

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Document Summary

Lecture 16: gluconeogenesis & pentose phosphate pathway march 29, 2016. Occurs when dietary sources of glucose are gone. Gng is synthesis of glucose from pyruvate: non-carbohydrate precursors, lactate, pyruvate, tcac intermediates, amino acids. Occurs mostly in liver: some does occur in kidney. Gluconeogenesis is not the exact reversal of glycolysis. Pyruvate to glucose does not occur by reversing the steps of glucose to pyruvate. There are three irreversible steps in glycolysis: phosphoenopyruvate to pyruvate + atp (glycolysis step 10, fructuose-6-phosphate to fructose-1,6-bisphosphate (glycolysis step, glucose to glucose-6-phosphate (glycolysis step 1) Net result of gng is reversal of these three steps, but by different reactions and using different enzymes. Many reactions are the reverse of glycolysis except for three important control points. At control points, different enzymes catalyze the reaction of gng. Pyruvate to pep requires 2 reactions (step 10 glycolysis) Reaction 1a: carboxylation of pyruvate: enzyme: pyruvate carboxylase, requires coenzyme biotin, a carrier of co2.

Related Questions

(BIOCHEMISTRY QUESTION)

A. Gluconeogenesis is not just the reverse of glycolysis. Briefly describe one of the steps catalyzed by different enzymes in glycolysis and gluconeogenesis.

B. Explain how a biochemist might dicover that a certain enzyme is allosterically regulated.

C. What are the regulatory implications for the cell with regard to ATP & AMP, given the relative concentrations of ATP & AMP in a cell?

D. Describe the function of fructose 2,6-bisphosphate in overriding the control of gycolysis and gluconeogenesis in liver cells in response to lowered blood glucose levels.

E. The human disease beriberi is caused by a deficiency of thiamine in the diet. People with severe beriberi have higher than normal levels of pyruvate in their blood & urine. Explain this observation in terms of specific enzymatic reaction(s).

My Responses: Could you tell me if these are correct? If not, could you provide the correct answer and explanation?

A. Its a cellular process in which glucose is produced from pyruvate, amino acids, lactate, and other biogenic precursors.

B. They might learn that an enzyme is allosterically regulated if that protein or enzyme undergoes a conformational change modulated by the binding of one or more modulators/effectors to alternate sites on the protein, resulting in a change in its activity. And they usually have more than one polypeptide chain.

C. The regulatory implications for the cell would be that all activity would increase and concentrations would go up unless bound to PFK-1 and then the overall activity would drop.

D. Low blood glucose is when glucagon signals the liver to produce and release more glucose (gluconeogenesis) and stop consumption. Fructose 2, 6-bisphosphate mediates rapid hormonal regulation of glycolysis and gluconeogenesis.

E. Pyruvate is the product of both carbohydrate and amino acid catabolism that enters cellular respiration in the mitochondria when converted to acetyl-CoA catalyzed by the PDH complex. The first step in the PDH complex reaction is a decarboxylation reaction that cannot be catalyzed without the enzyme thiamine pyrophosphate (TPP). This coenzyme is a derivative of thiamine or vitamin B1.

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BMCB 658 Lecture Notes - Lecture 16: Oxaloacetic Acid, Lysine, Decarboxylation

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