Insulin

  1. Nature & Source: Insulin is a 51-amino acid peptide hormone (molecular weight ~5.8 kDa) synthesized by β-cells of pancreatic islets as proinsulin, which is cleaved to active insulin and C‑peptide.

  2. Main Action: Lowers blood glucose by stimulating glucose uptake (via GLUT4) in muscle & adipose tissue and promoting glycogenesis, lipogenesis, and protein synthesis while inhibiting gluconeogenesis.

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What is Erythropoiesis? Describe the various stages in the development of RBC. Mention the factors needed for erythropoiesis.

What is Erythropoiesis? Erythropoiesis is the biological process by which red blood cells (RBCs, or erythrocytes) are produced in the body. It primarily occurs in the bone marrow of adults (and in the liver/spleen during fetal development). This process replaces old RBCs, which have a lifespan of about 120 days, with around 200-300 billion new RBCs produced daily in a healthy adult to maintain oxygen transport. Stages in the Development of RBCs RBC development starts from hematopoietic stem cells in the bone marrow and progresses through several stages, taking about 7 days to complete. Here's a concise overview of the key stages: Proerythroblast : The earliest committed cell; large with a high nucleus-to-cytoplasm ratio. It begins hemoglobin synthesis. Basophilic Erythroblast : Nucleus shrinks; cytoplasm stains blue due to ribosomes. Hemoglobin production ramps up. Polychromatophilic Erythroblast : Hemoglobin accumulation gives a mixed (polychromatic) stain. Cell size decreases....
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Iodine Number

Definition: The iodine number (or iodine value) is the  number of grams of iodine absorbed by 100 g of fat or oil . Significance: Measures the  degree of unsaturation  of fats and oils (higher value = more double bonds). Used to distinguish between  saturated and unsaturated fats . Examples (real data): Coconut oil: ~10 Olive oil: ~80 Sunflower oil: ~125 Linseed oil: ~175 Short Answer: It is the grams of iodine absorbed by 100 g of fat/oil, indicating its unsaturation. Higher iodine number means more double bonds (more unsaturated).
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Beri-Beri

Cause: Deficiency of  Vitamin B₁ (Thiamine) . Biochemical Role:  Thiamine is a coenzyme for  pyruvate dehydrogenase, α‑ketoglutarate dehydrogenase, and transketolase  – essential in carbohydrate metabolism. Types & Symptoms: Dry Beri-Beri:  Peripheral neuropathy, muscle weakness. Wet Beri-Beri: Cardiomegaly, tachycardia, edema, high-output cardiac failure. Real Data: In severe deficiency, erythrocyte transketolase activity decreases; normal activity is 42–86 μmol/min/L, but can drop below 25 μmol/min/L in Beri-Beri.
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