16. Digestion and absorption of carbohydrates in the gastrointestinal tract. Glycolysis – importance, chemical reactions, energy production under anaerobic and aerobic conditions, tissue specificity.Regulation. Metabolic fate of NADH and pyruvate – shuttle systems (malate and glycerophosphate shuttles). Clinical aspects – lactic acidosis, enzymopathies, hemolytic anemia.

Describe the process of carbohydrate digestion, including the enzymes involved and their sites of action in the gastrointestinal tract. What are the main classes of dietary carbohydrates? Describe the structure of different types of polysaccharides and how it affects their digestibility.

.

Explain how monosaccharides are absorbed in the small intestine, referencing the specific transporters involved and their transport mechanisms. What are the differences between the transport of glucose/galactose and fructose? Why is the phosphorylation of glucose important once it enters the cell?

.

Define glycolysis and explain its importance in energy metabolism. What are the two main phases of glycolysis, and what happens in each phase? What are the end products of glycolysis under aerobic and anaerobic conditions? Illustrate the key differences between aerobic and anaerobic glycolysis in terms of energy production and the fate of pyruvate.

.

List the 10 chemical reactions of glycolysis, specifying the enzymes involved, substrates, and products of each reaction. What are the three irreversible reactions in glycolysis? Why are these three reactions irreversible, and what is their importance in glycolysis regulation?

.

Describe how glycolysis is regulated, including the key enzymes involved and the mechanisms of allosteric and covalent regulation. How do ATP, AMP, citrate, and fructose 2,6-bisphosphate levels influence phosphofructokinase-1 activity? Explain the role of glucagon and insulin in the regulation of hepatic pyruvate kinase.

.

Explain the metabolic fate of NADH and pyruvate, discussing shuttle systems and the different metabolic pathways pyruvate can take. Describe the functioning of the glycerol 3-phosphate shuttle and the malate-aspartate shuttle. What is the importance of the oxidative decarboxylation of pyruvate? Why is the carboxylation of pyruvate considered an anaplerotic reaction?

.

Discuss the importance of tissue specificity in glycolysis, providing examples of how different tissues use glycolysis differently. Why do red blood cells depend on anaerobic glycolysis for ATP production? How does glucokinase in the liver differ from hexokinase in other tissues?

.

Define lactic acidosis, explaining its causes and consequences. What are the symptoms of lactic acidosis? How is lactic acidosis diagnosed and treated? (This information may require independent research as it is not provided in the sources.)

.

Describe the enzymopathies associated with glycolysis and how these can lead to hemolytic anemia. What is the most common enzymatic defect in glycolysis? Explain how pyruvate kinase deficiency affects the shape and survival of red blood cells.

.

Discuss the importance of diagnosing and treating clinical conditions related to glycolysis. What diagnostic tests are used to identify enzymatic defects in glycolysis? (This information may require independent research as it is not provided in the sources.) What are the treatment options for hemolytic anemia caused by enzymatic defects? (This information may require independent research as it is not provided in the sources.)

.