Review: Macromolecules

Macromolecules Overview

• Large molecules, or polymers, composed of smaller structural units called monomers.
• Four major biologically important macromolecules:
  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids

Condensation/Dehydration Synthesis Reaction

• Water is removed during the formation of new molecules.
• Monomers combine to form polymers through an anabolic reaction.
• Energy is required, and water is released.

Hydrolysis Reaction

• Breakdown of macromolecules where water is used to disassemble polymers into monomers.
• Catabolic reaction characterized by energy release.

Carbohydrates Functions

• Serve as primary energy sources, e.g., glucose is the main energy source.
• Act as building materials and cell surface markers for communication.
• Contain carbon, hydrogen, and oxygen in a 1:2:1 ratio (Formula: (CH2O)n).

Simple Carbohydrates

Monosaccharides

• Smallest structural units of carbohydrates (C6H12O6).
• Examples include glucose, fructose, and galactose.
• Polar and hydrophilic (water-soluble).
• Characterized by the number of carbons and functional groups, primarily –OH and carbonyl (=O) groups.

Carbonyl Types

• Aldehyde: At the end of the molecule; must have hydrogen attached to C=O.
• Ketone: Located in the middle of the molecule; both R groups are hydrocarbons.

Isomerism

• Isomers are monosaccharides with the same chemical formula but different atom arrangements (e.g., glucose, galactose, fructose all share C6H12O6).

Glucose Variants

• α-Glucose: -OH below the plane of the molecule.
• β-Glucose: -OH above the plane.

Disaccharides

• Formed by two monosaccharides linked through a condensation reaction, creating a glycosidic linkage.
• Examples:
  • Glucose + Glucose = Maltose (e.g., in infant formula, beer).
  • Glucose + Fructose = Sucrose (e.g., in sugar cane, table sugar).
  • Glucose + Galactose = Lactose (e.g., in milk).

Complex Carbohydrates

Oligosaccharides

• Composed of 3 to 10 monosaccharides linked together.
• Example: Raffinose (glucose, galactose, fructose) found in beans, peas, lentils, causing digestive issues due to enzyme lack.

Polysaccharides

• Formed from more than 10 monosaccharides linked, potentially hundreds.
• Types of polysaccharides include:
  • Starch: Glucose storage in plants, consisting of amylopectin (branched) and amylose (coiled).
  • Glycogen: Glucose storage in animals.
  • Dietary Fiber: Not energy-used; includes cellulose (plants) and chitin (organisms).

Starch Sources

• Found in grains, dried beans, pasta, bread, and potatoes.