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1.2 Biologically Important Molecules (Carbohydrates)

1.2 - Biologically Important Molecules

Macromolecules

  • Definition: Large complex molecules (polymers) made of many smaller structural units (monomers) covalently linked together.

    • Monomer: A small molecule that serves as the building block of polymers.

    • Polymer: A long-chain molecule composed of repeated patterns of monomers.

Key Elements in Biological Molecules

  • CHONP: Primary elements in biological macromolecules

    • CHO: Carbon, Hydrogen, Oxygen (found in carbohydrates and lipids)

    • CHON: Carbon, Hydrogen, Oxygen, Nitrogen (found in proteins)

    • Nucleic Acids: Contain CHONP (Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus)

Synthesis and Breakdown of Macromolecules

Condensation/Dehydration Synthesis Reaction

  • Anabolic Reaction: Construction of larger molecules from smaller units.

    • Energy Requirement: Energy is required.

    • Water Production: Water is released as a byproduct.

Hydrolysis Reaction

  • Definition: Process of breaking down polymers into monomers.

    • Catabolic Reaction: Larger molecules are broken down into smaller subunits.

    • Energy Release: Energy is released during this reaction.

    • Water Requirement: Water is used in the breakdown process.

Carbohydrates (CHO)

Functions

  • ** Source of Energy**: Main energy source for the body.

  • Structural Support: Provides structure, particularly in plants.

Types of Carbohydrates

  • Monosaccharides: Simplest sugars that provide immediate energy (e.g. Glucose and Fructose).

  • Disaccharides: Composed of two monosaccharides (e.g. Sucrose, Lactose, Maltose).

  • Polysaccharides: Long chains of monosaccharides (e.g. Starch, Glycogen, Cellulose).

Definitions

  • Simple Carbohydrates: Sugars, including Monosaccharides and Disaccharides.

  • Complex Carbohydrates: Include Oligosaccharides and Polysaccharides.

Monosaccharides

  • Definition: Single sugar units with 3 to 7 carbon atoms.

  • Example: C6H12O6 for Glucose, Galactose, Fructose.

Carbon Numbering for Simple Sugars

  • Monosaccharides like Glucose can be represented as C6H12O6 and they are isomers.

Disaccharides

  • Definition: Formed when two monosaccharides undergo condensation, creating a glycosidic linkage.

    • Examples:

      • Glucose + Glucose = Maltose

      • Glucose + Fructose = Sucrose

      • Glucose + Galactose = Lactose

Polysaccharides

  • Definition: Composed of many monosaccharides linked together.

Types of Polysaccharides

  1. Starch: Storage form of glucose in plants.

  2. Glycogen: Storage form of glucose in animals, found mainly in liver and skeletal muscles.

  3. Cellulose: Provides structural support in plant cell walls.

  4. Chitin: Structural support in the exoskeletons of arthropods and in fungal cell walls.

Dietary Fiber

  • Comprises plant polysaccharides that cannot be digested by humans due to lack of enzymes to break down glycosidic linkages.

Chitin

  • Provides structural support in the exoskeleton of insects, crabs, and lobsters, as well as in fungi cell walls.

  • Medical Uses: Utilized in manufacturing contact lenses and surgical thread.