Lipids

• What are the general types of lipids?

  Fats, oils, and waxes
• What elements do lipids contain?

  Carbon, hydrogen, and oxygen
• How do the oxygen atoms in lipids compare to those in carbohydrates?

  There are fewer oxygen atoms in lipids than in carbohydrates
• What is the solubility of lipids in water?

  Lipids are non-polar and insoluble in water
• What are lipids esters of?

  Organic (fatty) acids and alcohols
• How do saturated and unsaturated fatty acids differ in terms of their structure?

  Saturated fatty acids have only single bonds, while unsaturated fatty acids have one or more double bonds

  
• What are triglycerides composed of?

  Glycerol and fatty acids

  
• How many hydroxyl groups does a glycerol molecule have?

  Three hydroxyl groups

  
• What is the process by which triglycerides are formed?

  Condensation reactions between glycerol and fatty acids

  
• What is formed when a fatty acid attaches to a hydroxyl group of glycerol?

  An ester called a triglyceride

  
• What is the bond formed by the condensation of a fatty acid with a hydroxyl group called?

  An ester linkage
• What is the structure of fatty acid molecules?

  Long hydrocarbon chains with a carboxyl group at one end

  
• Why are lipids with saturated fatty acids more solid than those with unsaturated fatty acids?

  Saturated fatty acids have only single bonds, making them more tightly packed

  
• What are the roles of fats and oils in organisms?

  They serve as important energy stores
• How much energy do fats release compared to carbohydrates?

  Fats release twice as much energy per gram as carbohydrates
• Where is fat stored in animals?

  In adipose tissue beneath the skin and around organs
• What additional functions does adipose tissue perform besides storage?

  It provides protection, insulation, and buoyancy
• What is the waterproofing function of waxes?

  Waxes prevent water loss
• How do waxes differ from triglycerides?

  Waxes are esters of fatty acids and long-chain alcohols
• How does a waxy cuticle on a mesophytic leaf help reduce water loss?

  It forms an additional layer that prevents evaporation
• What are the components of a phospholipid molecule?

  Glycerol, two fatty acid chains, and a polar group with a phosphate group
• How do phospholipid molecules orientate themselves at interfaces?

  Their heads face water while their tails face inwards
• What structure do phospholipids form in cell membranes?

  The lipid bilayer
• What is the function of the cell surface membrane?

  It forms a selective barrier between the cell and the external environment
• What membranes do phospholipids form within cells?

  Membranes of the endoplasmic reticulum and organelles like chloroplasts and mitochondria
• What are the key roles of lipids in biological systems?

  • Energy storage
  • Protection of vital organs
  • Insulation
  • Buoyancy in aquatic mammals
  • Waterproofing in plants and animals
• What are the differences between saturated and unsaturated fats?

  • Saturated fats:
  • Only single bonds in hydrocarbon chains
  • Typically solid at room temperature
  • Unsaturated fats:
  • One or more double bonds in hydrocarbon chains
  • Typically liquid at room temperature

  
• What is the significance of the ester bonds in triglycerides and phospholipids?

  • Triglycerides: Formed by ester bonds between glycerol and fatty acids
  • Phospholipids: Formed by ester bonds between glycerol and fatty acids, with a phosphate group
• What is the process of forming triglycerides from glycerol and fatty acids?

  1. Glycerol undergoes condensation with three fatty acids
  2. Three molecules of water are released
  3. Ester linkages are formed

  
• How do phospholipids contribute to cell membrane structure?

  • Form a lipid bilayer
  • Polar heads face outward towards water
  • Non-polar tails face inward, away from water
  • Create a selective barrier for the cell