Carbohydrate Chemistry Overview

Carbohydrate Chemistry

• Carbohydrates are the most abundant form of organic matter on Earth. They are composed of carbon, hydrogen, and oxygen, and are produced through photosynthesis.
• Biological Importance of carbohydrates:
  • Primary source of metabolic energy for plants and animals.
  • Used to form key structural components like chitin in animals and cellulose in plants.
  • Building blocks for other molecules, including fats, amino acids, and nucleic acids.
  • Found in cell surface receptors, cell membranes, DNA, RNA, and vitamins B2 and C.
  • Dietary fiber can help lower blood glucose and cholesterol levels, and prevent constipation.
  • Sugars and other fermentable carbohydrates contribute to the action of oral bacteria, which can lower salivary pH and lead to tooth demineralization.

Carbohydrate Classification

• Carbohydrates are classified based on the number of sugar units in the chain:
  • Monosaccharides: Single sugar unit (e.g., glucose, fructose, galactose)
  • Disaccharides: Two sugar units (e.g., sucrose, lactose, maltose)
  • Oligosaccharides: 3-10 sugar units
  • Polysaccharides: More than 10 sugar units (e.g., starch, glycogen, cellulose)

Monosaccharides: Building Blocks of Carbohydrates

• Monosaccharides are the simplest forms of carbohydrates.
• Classification of Monosaccharides

  • Based on the presence of an aldehyde or ketone group:

    • Aldoses: Contain an aldehyde group.
    • Ketoses: Contain a ketone group.

  • Based on the number of carbon atoms in the backbone:

    • Trioses: 3 carbons (e.g., glyceraldehyde, dihydroxyacetone).
    • Tetroses: 4 carbons.
    • Pentoses: 5 carbons (e.g., ribose, deoxyribose, xylose, ribulose).
    • Hexoses: 6 carbons (e.g., glucose, fructose, galactose, mannose).
    • Heptoses: 7 carbons.

  • Based on the number of carbon atoms and active group:

    Number of Carbons	Aldoses	Ketoses
    Trioses	Glyceraldehyde	Dihydroxyacetone
    Tetroses	Erythrose	Erythrulose
    Pentoses	Ribose, Xylose	Ribulose, Xylulose
    Hexoses	Galactose, Glucose, Mannose	Fructose
    Heptoses	Heptose	Sedoheptulose

Biological Importance of Monosaccharides

• Ribose is a component of ribonucleic acid (RNA).
• Deoxyribose is a component of deoxyribonucleic acid (DNA).
• Glucose is the sugar found in blood.
• Fructose is the sugar found in semen.
• Galactose is synthesized in the mammary gland to make lactose (milk sugar).
• Mannose is a constituent of many glycoproteins.

Configuration of Monosaccharides

• Asymmetric Carbon: A carbon atom attached to four different chemical groups.
• Stereiosomers: Compounds with the same chemical formula but different spatial arrangement of their atoms.
• D and L Forms:
  • D-sugars: Have the hydroxyl group (OH) on the subterminal carbon atom on the right side.
  • L-sugars: Have the hydroxyl group (OH) on the subterminal carbon atom on the left side.
  • Almost all naturally occurring carbohydrates are D-configuration.

This quiz explores the fundamental concepts of carbohydrate chemistry, including their composition, biological importance, and classification. Learn about the roles carbohydrates play in metabolic energy, structural components, and their effects on health.