Carbohydrates - Leaving Cert - Biology Revision Notes

Composition of Carbohydrates

• Elements: Carbon, Hydrogen, Oxygen
• General Formula: ((CH_2O)_n)
• Ratio: 1:2:1_

Types of Carbohydrates

1. Monosaccharides (1 sugar unit)

• Examples:
  • Glucose (found in fruit)
  • Fructose (found in honey)

2. Disaccharides (2 sugar units)

• Examples:
  • Maltose (found in germinating seeds)
  • Lactose (found in milk)
  • Sucrose (common table sugar)

3. Polysaccharides (3 or more sugar units)

• Examples:
  • Starch (found in bread, pasta, potatoes)
  • Cellulose (found in vegetables, wholemeal bread)
  • Glycogen

Role of Carbohydrates

1. Structural Role

• Cellulose is a key component of plant cell walls

2. Metabolic Role

• Involves chemical reactions and processes that sustain life
• Catabolic reactions (e.g., respiration): Breakdown of larger molecules into smaller molecules
• Anabolic reactions (e.g., photosynthesis): Use of smaller molecules to form larger molecules

3. Energy Storage

• Starch: Stored in plants
• Glycogen: Stored in animals, particularly in muscles and the liver

Quick Definition Review

• Catabolic reaction: The breakdown of larger molecules into smaller molecules, e.g., digestion
• Anabolic reaction: The process of forming larger molecules from smaller ones, e.g., photosynthesis, protein synthesis

Revision Questions

• Which carbohydrate is a disaccharide?

  • Options: Glucose, Lactose, Starch, Fructose

• What describes an anabolic reaction?

  • Options: Digestion of food into amino acids, Photosynthesis producing glucose, Lipid breakdown for energy, Cell respiration releasing ATP

Next Topic: Lipids (Fats & Oils)