Carbohydrate: Monosaccharides

📌 Definition
🖇 Monosaccharides = simplest form of carbohydrates.
🖇 Aldehyde or ketone derivatives of polyhydric alcohols (e.g., glycerol).
📌 Classification
🟠 By Number of Carbons:
Trioses (3C): Glyceraldehyde, Dihydroxyacetone
Tetroses (4C): Erythrose, Erythrulose
Pentoses (5C): Ribose, Deoxyribose, Xylulose
Hexoses (6C): Glucose, Galactose, Fructose, Mannose
Heptoses (7C): Rare
🟣 By Functional Group:
Aldoses: contain aldehyde group (e.g., Glucose, Galactose)
Ketoses: contain ketone group (e.g., Fructose)
📌 Isomerism
🖇 D & L isomerism → based on asymmetric carbon configuration.
🖇 Aldose–Ketose isomerism → e.g., Glucose vs Fructose.
🖇 Epimers → differ at one carbon (not carbonyl), e.g., Glucose vs Galactose (C4).
🖇 α & β isomers → based on hydroxyl group position at anomeric carbon (C1 in aldoses).
📌 Clinical Importance of Monosaccharides
🟠 Pentoses:
Ribose & Deoxyribose → structure of RNA & DNA.
Ribose → part of ATP, GTP, NAD, NADP.
Xylulose → intermediate in uronic acid pathway.
🟣 Hexoses (esp. Glucose):
Main energy source (60–75% of daily calories).
Essential for CNS, skeletal muscle, RBCs, cornea, lens, retina.
Precursor for synthesis: lipids, amino acids, lactose, fructose, ribose.
Formation of glycolipids & glycoproteins.
Produces important compounds: 2,3-BPG (oxygen release), Lactate.
📌 Sugar Derivatives
🖇 Sugar acids → oxidation (e.g., Glucuronic acid).
🖇 Sugar alcohols → reduction (e.g., Sorbitol).
🖇 Deoxy-sugars → oxygen removal (e.g., Deoxyribose).
🖇 Amino sugars → e.g., Glucosamine.
🖇 Phosphate esters → e.g., Glucose-6-phosphate.
🖇 Glycosides → formed by condensation with other molecules.