biological molecules-lipids

• What are lipids made up of?

  Carbon, hydrogen, and oxygen
• Why are lipids insoluble in water?

  Due to their non-polar nature
• What are the main types of lipids in biology?

  • Triglycerides: Energy storage
  • Phospholipids: Form cell membranes
  • Steroids: Hormones like cholesterol
• What is the structure of triglycerides?

  One glycerol and three fatty acids
• How are triglycerides formed?

  By ester bonds via condensation reactions
• What is the reaction to form a triglyceride?

  Glycerol + 3 Fatty Acids → Triglyceride + 3 H2O
• What is esterification?

  The process of forming ester bonds
• What characterizes saturated fatty acids?

  No double bonds between carbon atoms
• Why are saturated fatty acids solid at room temperature?

  They pack tightly in straight chains
• What characterizes unsaturated fatty acids?

  One or more double bonds in the chain
• Why are unsaturated fatty acids liquid at room temperature?

  Kinks prevent tight packing of chains
• What are the functions of triglycerides?

  • Energy storage: High energy density
  • Insulation: Found in animals
  • Protection: Cushions vital organs
  • Waterproofing: Prevents water loss
• What is the structure of phospholipids?

  Glycerol, 2 fatty acids, and phosphate group
• What does amphipathic mean in phospholipids?

  Has both hydrophilic and hydrophobic parts
• What is the hydrophilic part of phospholipids?

  The polar phosphate head
• What is the hydrophobic part of phospholipids?

  The non-polar fatty acid tails
• What is the function of phospholipids in membranes?

  Forms the phospholipid bilayer
• What is selective permeability in membranes?

  Allows certain molecules to pass through
• Which molecules pass freely through membranes?

  Small/non-polar molecules like O2
• What is the structure of steroids?

  Four carbon rings with an OH group
• What is a function of cholesterol?

  Maintains membrane fluidity
• How does cholesterol regulate membrane permeability?

  By maintaining fluidity in the membrane
• What is one use of cholesterol in the body?

  To synthesize steroid hormones
• What is the procedure for the Emulsion Test?

  1. Add ethanol to the lipid sample and shake
  2. Add water and shake again
  3. White emulsion forms if lipids are present
• What are the key roles of lipids?

  • Energy storage (triglycerides)
  • Cell membrane structure (phospholipids)
  • Hormone production (steroids)
  • Waterproofing (waxy cuticle, oil on feathers)
  • Thermal insulation (fat stores in animals)