Carbohydrate: Disaccharides

📌 Definition
Disaccharides are carbohydrates composed of two monosaccharide units linked by a glycosidic bond.
🖇 Classification
🟣 Homo-disaccharides: formed from two identical monosaccharides.
🟠 Hetero-disaccharides: formed from two different monosaccharides.
📌 Types of Disaccharides
🟣 Homo-disaccharides
Maltose (Malt sugar): two D-glucose units, α-1,4 bond, found in malt and produced during starch digestion by amylase.
Isomaltose: two D-glucose units, α-1,6 bond, represents branching points in starch and formed during starch digestion.
Cellobiose: two β-D-glucose units, β-1,4 bond, obtained from partial hydrolysis of cellulose.
Trehalose: two D-glucose units, α-1,1 bond, found in fungi and yeast; used as a sweetener and food preservative.
🟠 Hetero-disaccharides
Lactose (Milk sugar): β-D-galactose + β-D-glucose, β-1,4 bond, synthesized by mammary glands.
Lactulose: β-galactose + β-fructose, β-1,4 bond, synthetic and non-absorbable sugar.
Sucrose (Table sugar): α-D-glucose + β-D-fructose, α-1,2 bond, found in sugar cane and sugar beets.
📌 Key Properties & Clinical Importance
🟣 Lactose (Milk Sugar)
🍼 Provides galactose for brain and nerve development and glucose for energy.
🍶 Least sweet, allowing higher milk consumption.
🚽 Acts as a laxative, preventing constipation.
🦠 Works as a prebiotic, promoting growth of beneficial gut bacteria and synthesis of vitamin K.
💪 Enhances absorption of calcium, phosphorus, and iron.
🟠 Lactulose
💊 Used to treat constipation and hepatic encephalopathy.
⚙️ Not absorbed; gut bacteria convert it into organic acids that trap ammonia (NH₃) as NH₄⁺.
💧 Has an osmotic effect, causing diarrhea and removing trapped toxins.
🚨 Sucrose (Table Sugar)
💉 Osmotically active; when given intravenously, it draws water into the bloodstream and helps reduce edema.