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.