Lipids Overview

Introduction

• Lipids are non-polar hydrocarbons, hydrophobic in nature.
• Found in aquatic animals' fur for protection from elements and drying off.
• Functions include long-term energy storage, insulation, hormone building, and cell membrane structure.

Types of Lipids

1. Fats

   • Comprised of glycerol and three fatty acids (triacylglycerol or triglycerides).
   • Formed through dehydration synthesis linked by ester bonds.
   • Fatty acids can be saturated (no double bonds) or unsaturated (one or more double bonds).

2. Saturated Fats

   • Single bonds, linear structure, pack tightly.
   • Solid at room temperature (e.g., butter, meat fats).
   • Associated with cardiovascular diseases.

3. Unsaturated Fats

   • One or more double bonds, cause kinks in the structure (cis and trans configurations).
   • Liquid at room temperature (e.g., olive oil).
   • Cis fats prevent tight packing, trans fats mimic saturated fats and are less healthy.
   • Trans fats artificially produced through hydrogenation.

4. Essential Fatty Acids

   • Must be obtained from diet (e.g., Omega-3 and Omega-6).
   • Found in fish, nuts.
   • Important for hormone production, reducing heart disease risk.

5. Waxes

   • Long fatty acid chains bonded to alcohols.
   • Waterproof, found on feathers, leaves, bacteria.

6. Phospholipids

   • Composed of two fatty acids, a glycerol backbone, and a phosphate group.
   • Amphipathic nature (hydrophilic head, hydrophobic tails).
   • Form cell membranes as a bilayer, creating a barrier.
   • Soap and shampoo utilize phospholipids to trap and wash away dirt.

7. Steroids

   • Fused ring structure, hydrophobic.
   • Includes cholesterol, important for hormones, vitamin D, bile salts.
   • Steroids affect membrane fluidity and can pass easily through cell membranes.

Lipids in Cell Membranes

• Phospholipid bilayer forms the plasma membrane.
• Creates a barrier to most substances but allows for lateral movement.
• Steroids and specific lipophilic substances can pass through easily.

Conclusion

• Next topic will focus on proteins as the third type of macromolecule.