lipids

• The hydrophobic tails are nonpolar, while the polar heads contain oxygen atoms.
• One end of phospholipids is hydrophilic (water-loving) due to its charged head group, while the other end is hydrophobic (water-hating).
• Phospholipid molecules have two fatty acid chains attached to glycerol through ester bonds.
• Lipids are an exception among macromolecules

  because they do not have polymers
• Lipids are made up of C, H, and O (C, H > O)
• The unifying feature of lipids is that they all have

  little or no affinity for water 🡪 Why?

  This is because their structures are

  dominated by nonpolar covalent bonds =

  hydrophobic
• lipids are the most common energy-storing

  molecule

  has more than twice the energy stored in

  carbohydrates
• What do you notice about the

  composition and structure of fats?

  The energy of lipids is stored in the

  hydrocarbon chain which is harder

  for cells to access

  Carbohydrates are more

  accessible and therefore broken

  down first

  
• What do you think are some

  functions that lipids have in living

  systems?

  • Digestion (e.g. bile)
  • Insulation (conserve body heat)
  • Food storage as adipose tissue as a source of
  • energy
  • Chemical Signaling (hormones)
  • Structural (cell membranes, nervous tissue)
  • Fat-soluble vitamins regulate body processes
  • Blood clotting – clotting factors are made from lipids
  • Nerve function – makes up the sheath around nerves
  • Protective coating – repels water (e.g. feathers and leaves)
• types of lipids?

  Fats

  Phospholipids

  Steroids

  Waxes
• Glycerol+3 fatty acids = Triglyceride


  tryglyceride

  
• triglycerides

  • Fatty acids are long hydrocarbon chains with a carboxyl group at the end
  • Fatty acids join a glycerol molecule by an ester linkage
  • Carried in the blood and stored in adipose (fat) tissue
  • The liver creates ketoacids (that can be used for energy) from fatty acids for respiration when blood sugar levels are low
  • Some fatty acids form local hormones
• what are the two types of fatty acids?

  saturated and unsaturated

  
• Properties of fatty acids (saturated)

  Saturated fatty acids contain only single

  covalent bonds between carbon atoms

  The fatty acid chain is "saturated" with

  hydrogen

  Saturated fatty acids can pack very tightly

  together

  Triglycerides with saturated fatty acids are

  solids at room temperature

  Found in animals (lard, butter, etc.)
• Properties of Fatty Acids (unsaturated)

  Monounsaturated fatty acids have one

  double bond

  Polyunsaturated fatty acids have multiple

  double bonds

  Double bonds cause the chains to kink

  Lipids with unsaturated fatty acids have

  increased fluidity

  found in plants (oils)
• Unsaturated fatty acid chains cannot fit closely together
• Phospholipids

  Composed of a glycerol

  molecule which is

  attached to:

  two non-polar fatty

  acids (tail)

  highly polar

  phosphate group

  (head)

  
• which one should make up the cell membrane

  d

  
• Properties of Phospholipids

  When added to water, two possible

  conformations result:

  A) micelle

  B) lipid bilayer

  
• Steroids

  • Lipids with four carbon ring framework
  • Used as drugs to reduce inflammation (e.g. asthma)
  • Anabolic steroids mimic male sex hormones to build
  • muscle mass
  • Used by cancer/AIDS patients but is abused by
  • others
• Steroids (cholesterol)

  • Vital component of lipid bilayer in cell membranes
  • Maintains fluidity in extreme conditions
  • Incorporated into vitamins and bile
  • Part of sex hormones
• waxes are Lipids containing long-chain

  fatty acids that are linked to

  alcohols or carbon rings. Very firm molecules.
• Cutin – a wax produced by the

  epidermal cells of plants to form

  a water-resistant coating on

  leaves, fruit, and stems

  Helps plants resist disease and

  conserve water