Lipids/fats

• saturated fatty acids


  no double bonds between carbon atoms (c-c-c-c-c-c)
• mono-unsaturated


  one double bond between carbon atoms (c-c-c-c-c=c)
• poly unsaturated


  more than one double bond between carbon atoms.

  double bond cause molecules to bend (cant pack together making them liquid at room temp e.g oils) (c-c-c=c-c=c-c)
• unsaturated fatty acids (cis and trans)

  • creates biggest kink in fatty acids
  • produces chains unable to pack closely together
  • weak attractive forces
  • leading to liquid (e.g oil)
• phospholipids


  amphipathic: both hydrophilic and hydrophobic

  tails: hydrophobic heads: phosphate, charged, hydrophilic
• steroids and cholesterol

  • steroid alcohol helps maintain fluidity of cell membranes
  • made of 4 carbon rings as opposed to glycerol or fatty acids
  • small and hydrophobic (no charge)
  • used to make steroids including hormones e.g oestrogen and testosterone
• lipids 


  uses: insulation and energy store

  types: triglycerides, waxes and steroids
• lipids as adipose tissue

  • buoyancy: less dense than water (float)
  • heat insulation: reduces heat loss
  • protection: around delicate organs