JNTU B.Pharmacy I Year BIOCHEMISTRY Previous Question Paper (September - 2024 - R17)

Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia resulting from defects in insulin secretion, insulin action, or both, leading to disturbances in carbohydrate, fat, and protein metabolism.

The classic signs and symptoms include polyuria (excessive urination), polydipsia (excessive thirst), polyphagia (excessive hunger), unexplained weight loss, blurred vision, and fatigue.

Gluconeogenesis is the metabolic process by which the body synthesizes glucose from non-carbohydrate precursors, primarily occurring in the liver and to a lesser extent in the kidneys. The key precursors include lactate, glycerol, and glucogenic amino acids like alanine.

The pathway involves the reversal of glycolysis, but it bypasses the three irreversible steps of glycolysis (catalyzed by hexokinase, phosphofructokinase-1, and pyruvate kinase) using four unique enzymes: pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase.

The significance of this pathway includes:

• Maintaining blood glucose levels during fasting, starvation, or intense exercise to ensure a continuous supply of energy for glucose-dependent tissues like the brain and red blood cells.
• Clearing metabolic waste products such as lactate (produced by muscles) and glycerol (from adipose tissue) from the blood.
• Providing intermediates for other biosynthetic pathways when glucose levels are sufficient.