Fats and Lipids

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Fats and Lipids
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Lipids

• Lipids are varied in structure.
• Many are insoluble in water because they lack
  polar groups.
• Types of Lipids and their Functions
• 1. Fat provides insulation and energy storage.
• 2. Phospholipids form plasma (cell) membranes
• 3. Steroids are important cell messengers.
• 4. Waxes are for protection/insulation.

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Lipids

• Fats and Oils 3 fatty acids Glycerol
• A fatty acid is a long hydrocarbon chain with a
  carboxyl (acid) group at one end. (-COOH)
• Because the carboxyl group is a polar group,
  fatty acids can be slightly soluble in water.
• Most fatty acids in cells contain 16 to 18 carbon
  atoms per molecule. The longer the chain the
  less water soluble it is.
• Glycerol is a water-soluble compound with three
  hydroxyl groups.

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Lipids

• Triglycerides are glycerol joined to three fatty
  acids by condensation synthesis.
• Fats are triglycerides containing saturated fatty
  acids (e.g., butter is solid at room
  temperature). Generally from animals
• Oils are triglycerides with unsaturated fatty
  acids (e.g., corn oil is liquid at room
  temperature). Generally from plants
• Animals use fat rather than glycogen for
  long-term energy storage fat stores more
  energy.(9cal/g)

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Types of Fatty Acids

• Saturated fatty acids have no double bonds
  between their carbon atoms.
• Unsaturated fatty acids have double bonds in the
  carbon chain where there are less than two
  hydrogens per carbon atom.
• Saturated animal fats are associated with
  circulatory disorders plant oils can be
  substituted for animal fats in the diet.

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Lipids

• Waxes
• Waxes form a protective covering that prevent
  water loss in plants, maintain animal skin and
  fur.
• Steroids
• Cholesterol is a part of an animal cells
  membrane and a precursor of other steroids,
  including the sex hormones.
• Testosterone is the male sex hormone.
• Steroids act as messengers and help turn on or
  turn off genes. Thus they help control cell
  activity

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Lipids

• Phospholipids
• Phosphate group is the polar head
• Hydrocarbon chains become the nonpolar tails.
• Hey! Hey! Hey! This is why phospholipids are
  important!!
• The plasma membrane which surrounds living cells
  is a phospholipid bilayer.

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