Lesson 11. CARBOHYDRATE METABOLISM. AEROBIC AND ANAEROBIC GLYCOLYSIS. OXIDATIVE DECARBOXYLATION OF PYRUVATE. GLYCOGEN METABOLISM

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Task

Guidelines for performing the task

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Study the structure of major dietary carbohydrates: monosaccharides,

disaccharides and polysaccharides

1. Write down formulas of α-D-glucose, ß-D-glucose, D-galactose and D-fructose.

2. Write down formulas of sucrose, lactose and maltose. Characterize the type of glycoside bond in these disaccharides.

3. Write a fragment structure of amylose, amylopectin, and glycogen. Determine the types of bonds between monosaccharide residues

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Study the main pathways of glucose metabolism in tissues

1. Write down the reaction of phosphorylation of glucose, list the enzymes and describe their features. What is the biological significance of this process? Can phosphorylated glucose leave the cells?

2. Write a scheme of the main pathways of glucose-6-phosphate conversion in tissues

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Study the dichotomy glucose oxidation - glycolysis

1. Explain the terms dichotomic oxidation and glycolysis.

2. Write down the reactions and enzymes of glycolysis.

3. Point out irreversible reactions and reactions that are accompanied by formation and use of ATP.

4. Write the net equation of glycolysis.

5. Describe the biological significance of glycolysis and list the tissues which are characterized by high rate of this pathway.

6. Calculate the energy balance of glycolysis

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Study anaerobic glycolysis, oxida-tive decarboxyl-ation of pyruvate, and aerobic breakdown of glucose to end product of catabolism

1. Write down the scheme of anaerobic glycolysis. Point out it role.

2. Make a schematic representation of the structure of pyruvate dehydrogenase multienzyme complex.

Write down partial reactions of oxidative decarboxylation of pyruvate and its net equation.

4. Point out the stages of aerobic breakdown of glucose to end product of catabolism.

5. What is metabolic fate of NADH produced in glycolysis? What is the shuttle mechanism? Write down the reactions of hydrogen atoms transport cross inner mitochondrial membrane using glycerol phosphate shuttle mechanism.

8. Calculate the energy balance of complete oxidation of glucose, glucose 6-phosphate, fructose 1,6-bisphosphate in aerobic conditions

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Study biosynthesis of glycogen

1. Describe the distribution of glycogen in liver, kidneys, cardiac muscle, skeletal muscle, etc.

2. Write down reactions of glycogen biosynthesis. What is the key regulatory enzyme of this pathway?

3. Explain the cause of glucose deposition in cells as glycogen rather than a free monosaccharide

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Study ways of gly-cogen decomposition in tissues

1. Write down the scheme of phosphorolytic pathway of glycogen breakdown.

2. Write down the scheme of amylolytic pathway of glycogen breakdown.

3. Characterize the principal distinction in significance of glycogen decomposition in the liver and other tissues.

4. Write down the definition of the term glycogen storage diseases.

5. Fill in the table: write the defective enzyme and main symptoms of glycogen storage diseases

Type and name of disease

Defective enzyme

Symptoms

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Study hormonal regulation of gly-cogen metabolism in the liver

1. Write down the key regulatory enzymes of glycogen synthesis and breakdown.

2. Write down the hormones that stimulate glycogen synthesis and glycogen breakdown.

3. Write down the scheme of regulation of glycogen beakdown by epi-nephrine and glucagon.

4. Describe the scheme of activation of glycogen synthesis by insulin