Govt. Exams
Entrance Exams
The Cori cycle describes lactate produced in muscles during anaerobic glycolysis being transported to the liver where it is converted back to glucose via gluconeogenesis, which is then returned to muscles.
Type 2 diabetes is characterized by insulin resistance (defective glucose uptake and utilization) and progressive β-cell dysfunction. Impaired fasting glucose (100-125 mg/dL) is a prediabetic state. Fasting glucose ≥126 mg/dL on 2 occasions is diagnostic for diabetes.
The oxidative phase of PPP generates 2 NADPH per glucose-6-phosphate, essential for fatty acid synthesis, cholesterol synthesis, and antioxidant defense (glutathione reduction). This is particularly important in adipose tissue, liver, and RBCs.
Cellulose contains β(1→4) glycosidic bonds linking glucose units, making it indigestible to humans (no cellulase enzyme). Starch contains α(1→4) bonds, which are digestible.
HbA1c is formed through non-enzymatic glycation of hemoglobin by glucose, reflecting average blood glucose over 2-3 months (RBC lifespan). Normal HbA1c <5.7%, diagnostic for diabetes ≥6.5%.
The anomeric carbon (C1 in glucose) is the carbon that becomes chiral when the open-chain form cyclizes to form the hemiacetal. This is the site of α/β isomerism.
Pyruvate carboxylase catalyzes the first committed step of gluconeogenesis, converting pyruvate to oxaloacetate. Lactate is converted to pyruvate by LDH, then to glucose via gluconeogenesis.
Glycogen branching enzyme transfers segments of 6-7 glucose residues from the outer chains to create α(1→6) branch points, increasing solubility and accessibility for glycogen phosphorylase.
Aldose reductase catalyzes the reduction of glucose to sorbitol using NADPH. Sorbitol dehydrogenase catalyzes the oxidation of sorbitol to fructose in the second step of the polyol pathway.
The Maillard reaction is a non-enzymatic browning reaction between carbonyl groups of reducing sugars and amino groups of proteins/amino acids, producing AGEs. This is significant in glycemic control and diabetes complications.
