Lipids

• Lipids are not polymers

  made of: fatty acids and glycerol
• Triglycerols = 3 fatty acids connected to one glycerol

  fats - solid at room temperature

  oilds - liquid at room temperature
• lipids are made up of carbon , hydrogen and oxygen
• Lipids - function:

  • a source of energy
  • store of energy (adipose tissue)
  • biological membranes
  • thermal insulators
  • buoyancy
  • protection - cuticle of leaf and internal organs
  • metabolic source of water
  • hormones
• Glycerol structure:

  
• Fatty acid structure:

  
• Fatty acids:

  • an acid group at one end (COOH)

  saturated or unsaturated
• Saturated fatty acid:

  • single bonds
  • straight molecules = compact
  • bad for you - blocks arteries
  • solid at room temperature - fats
• Unsaturated fatty acid:

  • crooked a bit bent
  • less compacted
  • one or more double bonds between carbon atoms
  • liquid at room temperature - oils
• Polyunsaturated:

  • more than one double bond between carbons

  Monounsaturated

  • only one double bonds between carbons
• animal lipids are often saturated and occur as fats

  plant lipids are often unsaturated and occur as oils
• triglycerides:

  • insoluble in water
  • non-polar
  • hydrophobic
• roles of triglycerides:

  • energy reserve
  • insulators against heat loss
  • buoyancy
  • protection (vital organs)
  • metabolic source of water
• Phospholipid structure:

  head - polar and hydrophilic

  tail - non-polar and hydrophobic

  bilayer - plasma membrane, double layer with heads facing outwards. This forms a phospholipid bilayer

  any non-polar molecule can pass through the bilayer
• Cholesterol

  • small molecule 4 carbon based rings
  • found in all biological membranes
  • small, narrow & hydrophobic
  • helps regulate fluidity & strength of membrane
• triglycerides are bonded together by ester bonds and the reaction is called esterification (type of condensation reaction)
• when a fatty acid and three glycerols join together this produces three waters and bonded by ester bonds
• phospholipid is a modified triglyceride where it has a phosphate head instead and 2 fatty acid tails