lipids

• lipids are macromolecules
• lipids are non-polar molecules
• lipid are insoluble in water
• lipids do dissolve in organic solvents like alcohol or ethanol
• lipids are made up of two molecules

  fatty acids and glycerol
• what are the two types of lipids

  Triglycerides and phospholipids
• Triglycerides are formed by a condensation reaction between one molecule of glycerol and three molecules of fatty acids
• the bond formed between the triglyceride is called an ester bond
• Saturated fatty acids

  Only has single bonds no double bonds between carbon's
• Unsaturated fatty acids

  One or more double bonds between carbons
• monounsaturated fatty acids

  Only one double bonds between carbon
• Polyunsaturated fatty acids

  Many double bonds between carbon
• Properties of triglycerides

  • High ratio of hydrogen and carbon to oxygen
  • large - long hydrocarbon chain
  • non-polar long hydrocarbon chain is non-polar which is much larger than Polar glycerol
  • in water triglycerides do not dissolve
• Functions of triglycerides

  • Enable the release of energy via respiration
  • energy storage molecule
  • provides insulation
  • high ratio of carbon and hydrogen to oxygen makes a good energy source
  • triglycerides have low mass to energy ratio
  • insoluble won't affect water potential
• Phospholipids are formed by condensation reaction between one glycerol molecule two fatty acid chains and a phosphate group
• phospholipid heads are hydrophilic and mix with water
• Phospholipid tails are hydrophobic and don't mix with water
• Phospholipids are insoluble in water
• In water the hydrophilic head position themselves on the outside as they are charged and hydrophobic tails crusted together on the inside as they are repelled by water this is called the phospholipid bilayer
• The phospholipid bilayer forms a barrier that separates the cell from its environment, it also allows selective transport of substances into or out of the cell.
• The phospholipid bilayer is a useful property as it allows phospholipids to form the membrane found within and around cells