Biochemistry Review Chapters: 10, 13, 14, & 15
 Chapter 10: Lipids
• Biological Functions of Lipids:
o Storage of energy
▪ Reduced compounds: lots of available energy
▪ Hydrophobic nature: good packing
o Insulation from environment
▪ Low thermal conductivity
▪ High heat capacity (can “absorb” heat)
▪ Mechanical protection (can absorb shocks)
o Water repellant
▪ Hydrophobic nature: keeps surface of the organism dry
• Prevents excessive wetting (birds)
• Prevents loss of water via evaporation
o Buoyancy control and acoustics in marine mammals
▪ Increased density while diving deep helps sinking (just a hypothesis)
▪ Spermaceti organ may focus sound energy: sound stun gun?
• More functions:
o Membrane structure
▪ Main structure of cell membranes
o Cofactors for enzymes
▪ Vitamin K: blood clot formation
▪ Coenzyme Q: ATP synthesis in mitochondria
o Signaling molecules
▪ Paracrine hormones (act locally)
▪ Steroid hormones (act body-wide)
▪ Growth factors
▪ Vitamins A and D (hormone precursors)
o Pigments
▪ Color of tomatoes, carrots, pumpkins, some birds
• Depending on wave lengths is what gives off color
o Antioxidants
▪ Vitamin E
• Classification of lipids:
o Based on the structure and function
▪ Lipids that do not contain fatty acids: cholesterol, terpenes,…
▪ Lipids that contain fatty acids (complex lipids)
• Can be further separated into
o Storage lipids and membrane lipids