Monosaccharides and Their Derivatives

Sugar Phosphates

• Sugar Phosphates: A sugar molecule with a phosphate group attached.
  • Example: β-D-Glucose-1-phosphate (phosphate on carbon 1).
  • Example: α-D-Fructose-1,6-bisphosphate (phosphates on carbons 1 and 6).
• ATP: Adenosine 5'-triphosphate, a nucleotide with three phosphates; crucial for energy transfer in cells.

Deoxy Sugars

• Deoxy Sugars: Sugars with one or more oxygen atoms missing.
  • Examples: Deoxyribose, RNOs, Fucose.
• Deoxyribose in DNA: Carbon 2 lacks an O group, impacting structure and function.

Amino Sugars

• Amino Sugars: An -OH group is replaced by an amine group (-NH₂).
  • Examples: β-D-Glucosamine, β-D-Galactosamine.
• Note: Glucose and Galactose are isomers differing at one stereocenter.

Sugar Alcohols

• Sugar Alcohols: Reduced form of sugars, missing aldehyde/ketone group.
  • Examples: Sorbitol, Mannitol, Xylitol.
  • Cannot form closed rings except for inositol.

Glycosidic Bond Formation

• Glycosidic Bonds: Linkage between two monosaccharides forming a disaccharide.
  • Reaction between the hemiacetal group of one sugar and the hydroxyl group of another.
  • Results in a dehydration reaction (water molecule released).

Disaccharide Examples

• Lactose: β-D-Galactose linked to β-D-Glucose.
  • Glycosidic Linkages:
    • α 1-4: Example with two α-D-Glucoses.
    • β 1-4: Example with β-D-Galactose and β-D-Glucose (lactose).
    • α 1-2: Sucrose, composed of α-D-Glucose and β-D-Fructose.

Important Notes on Digestion

• Digestion of Sugars:
  • Human bodies can easily digest α-glycosidic bonds (e.g., sucrose, maltose).
  • β-glycosidic bonds (e.g., lactose) require specific enzymes (e.g., lactase).
  • Lactose intolerance occurs due to lack of lactase enzyme necessary for β-glycosidic bond digestion.