Lipids are the type of molecule that includes examples with a long-chain carbon backbone, such as fatty acids and triglycerides.

These hydrocarbon chains, often 16 to 18 carbons long, form the structural core of fats and oils, enabling energy storage and membrane formation.

Why Lipids?

Lipids like stearic acid feature unbranched chains of carbon atoms bonded to hydrogen, creating a hydrophobic backbone essential for their nonpolar nature. Unlike carbohydrates (ring or short-chain structures) or nucleic acids (sugar- phosphate backbones), lipids rely on these extended chains for fluidity in cell membranes.

Common Examples

  • Fatty acids : Straight chains ending in a carboxyl group, e.g., palmitic acid (C16).
  • Triglycerides : Glycerol linked to three fatty acid chains.
  • Phospholipids : Similar chains with polar heads for bilayers.

Comparison of Biomolecule Backbones

Biomolecule| Backbone Type| Example Structure
---|---|---
Lipids| Long carbon chain| CH3-(CH2)n-COOH 13
Carbohydrates| Rings/short chains| Glucose rings 1
Proteins| Peptide bonds (N-CĪ±)| Amino acid chain 1
Nucleic Acids| Sugar-phosphate| DNA backbone 1

TL;DR: Lipids, due to fatty acids' long hydrocarbon chains.

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