2.19.4 Waxes

Introduction

Waxes are a group of lipids that are esters of long-chain fatty acids with long-chain alcohols. They are solid at room temperature and are used by plants and animals for waterproofing and protection. Waxes also have many industrial uses.

Definition

Waxes: Waxes are esters of long-chain fatty acids with long-chain alcohols.

In simple words: Waxes are lipids that are solid at room temperature and are used for waterproofing and protection.

Core Concept

• Waxes are esters of long-chain fatty acids with long-chain alcohols.
• They are solid at room temperature.
• They are hydrophobic (water-repellent).
• They are used by plants and animals for waterproofing and protection.
• Waxes also have many industrial uses.

Detailed Explanation

Structure of Waxes

• Long-chain fatty acid – Usually 14 to 36 carbons.
• Long-chain alcohol – Usually 16 to 30 carbons.

Reaction: Fatty Acid + Alcohol → Wax + Water

Example: Palmitic Acid + Cetyl Alcohol → Cetyl Palmitate + Water

Natural Waxes

Synthetic Waxes

Roles of Waxes

• Polishing – Effective in polishing.
• Waterproofing – Provide waterproofing.
• Anti-fouling – Prevent fouling (accumulation of organisms).
• Cosmetics and crayons – Used to form cosmetics and crayons.
• Candles – Used to make candles.
• Car waxes – Used in car waxes.
• Paints, inks, adhesives, and tyres – Used to produce paints, inks, adhesives, and tyres.

Biological Roles of Waxes

Intermediate Level

Structure of Waxes in Detail

Natural Waxes in Detail

Synthetic Waxes in Detail

Roles of Waxes in Detail

Important Points

• 1. Phospholipids are derived from phosphatidic acid.
• 2. A phosphatidic acid molecule is most similar to a diglyceride that it contains:
• - A glycerol
• - Two fatty acids esterified with first and second -OH groups of glycerol
• - A phosphate group esterified with third -OH group of glycerol
• 3. A phospholipid is formed when phosphatidic acid combines with one of the four organic compounds:
• - Choline (a nitrogenous base)
• - Ethanolamine (an amino alcohol)
• - Inositol (an amino alcohol)
• - Serine (an amino acid)
• 4. Most common type of phospholipid is phosphatidylcholine also called lecithin in which choline is attached to phosphate group of phosphatidic acid.
• 5. One end of the phospholipid molecule, containing the phosphate group and additional compound, is hydrophilic (polar and readily soluble in water).
• 6. The other end, containing the fatty acid side chains, is hydrophobic (nonpolar and insoluble in water).
• 7. These phospholipids are major constituents of lipid bilayer of cell membrane.
• 8. Terpenes are synthesized from a five-carbon building block known as the isoprene unit.
• 9. This unit condenses in different ways to form many compounds.
• 10. Two isoprene units form a monoterpene (e.g., menthol).
• 11. Four isoprene units form a diterpene (e.g., vitamin A, phytol — chlorophyll tail).
• 12. Six isoprene units form a triterpene (e.g., ambrein).
• 13. Natural rubber is a polyterpene.
• 14. Waxes are esters of long-chain fatty acids with long-chain alcohols.
• 15. Roles of waxes:
• - Effective in polishing, waterproofing, anti-fouling.
• - Used to form cosmetics and crayons, candles, car waxes.
• - Used to produce paints, inks, adhesives, and tyres.

Remember

• - Phospholipids = derived from phosphatidic acid
• - Phosphatidic acid = glycerol + 2 fatty acids + phosphate
• - Phospholipid = phosphatidic acid + choline/ethanolamine/inositol/serine
• - Most common = phosphatidylcholine (lecithin)
• - Amphipathic = hydrophilic head + hydrophobic tails
• - Functions: Membrane structure, permeability, protein fixation, cell signaling, bile, fat absorption, ETC, inhibit fat accumulation, transport cholesterol, surfactants
• - Terpenes = isoprene units
• - Monoterpene = 2 units (menthol)
• - Diterpene = 4 units (vitamin A, phytol)
• - Triterpene = 6 units (ambrein)
• - Polyterpene = many units (natural rubber)
• - Waxes = long-chain fatty acids + long-chain alcohols
• - Roles: Polishing, waterproofing, anti-fouling, cosmetics, crayons, candles, car waxes, paints, inks, adhesives, tyres

Common Mistakes

• 1. Confusing phospholipids with triglycerides – Phospholipids have a phosphate group; triglycerides do not.
• 2. Thinking phospholipids are only hydrophobic – Phospholipids are amphipathic (both hydrophilic and hydrophobic).
• 3. Confusing the four organic compounds in phospholipids – Choline, ethanolamine, inositol, serine.
• 4. Forgetting that lecithin is phosphatidylcholine – Lecithin is the common name for phosphatidylcholine.
• 5. Confusing the number of isoprene units in terpenes – Monoterpene = 2; Diterpene = 4; Triterpene = 6; Polyterpene = many.
• 6. Thinking terpenes are only from plants – Some terpenes are from animals (e.g., ambrein from sperm whale).
• 7. Confusing waxes with fats – Waxes are esters of long-chain fatty acids with long-chain alcohols; fats are esters of glycerol with fatty acids.
• 8. Thinking waxes are only synthetic – Waxes can be natural (beeswax, carnauba wax) or synthetic (paraffin wax).
• 9. Forgetting that waxes are solid at room temperature – Waxes are solid at room temperature because of their long hydrocarbon chains.
• 10. Confusing the roles of phospholipids and waxes – Phospholipids = membrane structure; Waxes = waterproofing.
• 11. Thinking phospholipids are only in cell membranes – Phospholipids also have other functions (fat absorption, ETC, cholesterol transport).
• 12. Forgetting the role of phospholipids as surfactants – Phospholipids act as surfactants in the respiratory system.

Quick Revision

• Phospholipids are derived from phosphatidic acid.
• A phosphatidic acid molecule is most similar to diglyceride that it contains a glycerol, two fatty acids esterified with first and second OH groups of glycerol and a phosphate group esterified with third OH group of glycerol.
• A phospholipid is formed when phosphatidic acid combines with one of the four organic compounds such as choline (a nitrogenous base), ethanolamine (an amino alcohol), inositol (an amino alcohol) and serine (an amino acid).
• Most common type of phospholipid is phosphatidylcholine also called lecithin in which choline is attached to phosphate group of phosphatidic acid.
• One end of the phospholipid molecule, containing the phosphate group and additional compound is hydrophilic i.e., polar and readily soluble in water.
• The other end, containing the fatty acid side chains, is hydrophobic i.e., nonpolar and insoluble in water.
• These phospholipids are major constituents of lipid bilayer of cell membrane.
• All the terpenes are synthesized from a five-carbon building block known as isoprene unit.
• This unit condenses in different ways to form many compounds.
• Two isoprene units form a monoterpene e.g., menthol, four form a diterpene e.g., vitamin A, phytol (chlorophyll tail) and six form a triterpene e.g., ambrein.
• Natural rubber is a polyterpene.
• Roles of Waxes:
• Wax is effective in polishing, water proofing, anti-fouling.
• It is used to from cosmetics and crayons, candles, car waxes.
• Waxes are used to produce paints, inks, adhesives, and tyres.

60-Second Revision

• Phospholipids = derived from phosphatidic acid
• Phosphatidic acid = glycerol + 2 fatty acids + phosphate
• Phospholipid = phosphatidic acid + choline/ethanolamine/inositol/serine
• Most common = phosphatidylcholine (lecithin)
• Amphipathic = hydrophilic head + hydrophobic tails
• Functions: Membrane structure, permeability, protein fixation, cell signaling, bile, fat absorption, ETC, inhibit fat accumulation, transport cholesterol, surfactants
• Terpenes = isoprene units
• Monoterpene = 2 units (menthol)
• Diterpene = 4 units (vitamin A, phytol)
• Triterpene = 6 units (ambrein)
• Polyterpene = many units (natural rubber)
• Waxes = long-chain fatty acids + long-chain alcohols
• Roles: Polishing, waterproofing, anti-fouling, cosmetics, crayons, candles, car waxes, paints, inks, adhesives, tyres
• Warning: Phospholipids are not triglycerides. They are amphipathic. Terpenes are made of isoprene units. Waxes are not fats. Waxes are solid at room temperature. Do not confuse the number of isoprene units in different terpenes.