Lecture Notes: Carbohydrates

Types of Macromolecules

• Carbohydrates
• Proteins
• Fats
• Nucleic Acids (Nucleotides)

Composition of Carbohydrates

• Made of carbon, hydrogen, and oxygen
• Carbohydrates = "carbo" (carbon) + "hydrate" (water, H2O)
• All macromolecules consist of hydrocarbons

Structure of Carbohydrates

• Ring-shaped structures
• Types:
  • Monosaccharides: One sugar molecule (e.g., glucose, fructose, galactose)
  • Disaccharides: Two sugar molecules linked together (e.g., sucrose, lactose)
  • Polysaccharides: Many sugar molecules linked (e.g., glycogen, starch, cellulose)

Role of Carbohydrates

• Comprise 1% of human body mass
• Primary role: Energy production
• Found in cell membranes and genetic material

Types of Monosaccharides

• Glucose: Main energy source
• Fructose
• Galactose
• All have the same chemical formula: C6H12O6 (isomers)
• Converted to glucose in the liver

Disaccharides Formation

• Formed via Dehydration Reaction (removal of water molecule)
  • Example: Glucose + Fructose → Sucrose
  • Example: Glucose + Galactose → Lactose
• Broken down via Rehydration Reaction (adding water molecule back)
  • Enzyme needed: Lactase for lactose
  • Lack of lactase → Lactose intolerance → Diarrhea

Polysaccharides

• Glycogen: Animal storage form of glucose
• Starches: Plant storage polysaccharides
• Cellulose: Plant polysaccharide, indigestible in humans
  • Cows can digest cellulose
  • Forms dietary fiber in humans

Digestion and Function

• Humans lack enzymes to break down cellulose
• Enzymes can break down starch and glycogen
• Structural differences:
  • Cellulose: Long linear chains
  • Starches: Branched chains
  • Glycogen: Highly branched, storage form in humans

Summary

• Carbohydrates are crucial for energy production and storage.
• They function in structural roles, but digestion varies based on structure and enzyme presence.
• Understanding carbohydrate types and their metabolism is vital for comprehending energy production and nutritional science.