Ch. 5.3: LIPIDS

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Ch. 5.3 LIPIDS

• Objectives
• Identify a general characteristic of lipids.
• Describe the structure and function of fats.
• Describe the structure and function of steroids.

• Vocabulary
• Lipid
• Hydrophobic
• Fat
• Saturated fat
• Unsaturated fat
• Steroid
• Cholesterol

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5.3 Lipids

• Waxes or oils or fats
• HYDROPHOBIC!
• Also made of C, H O, but lower proportion of
  oxygen
• Lipids store more energy than carbohydrates
  because they have twice as many energy rich (C-H)
  bonds than carbohydrates.
• 1 Lipid 3 fatty acids 1 glycerol molecule
  (monomers)
• Example Triglyceride (polymer) Composed of 3
  fatty acid molecules joined to 1 Molecule of
  alcohol glycerol.

• FUNCTIONS
• Store energy
• Chemical signals to cells
• Boundary to water in cells (IN CELLMEMBRANE)
• Cushion organs

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• A fatty acid is a long hydrocarbon chain with a
  carboxyl (acid) group at one end.
• The Carboxyl End (HEAD) POLAR and HYDROPHILIC.
• The Hydrocarbon End (TAIL) NONPOLAR and
  HYDROPHOBIC.
• Saturated fatty acids have no double bonds
  between their carbon atoms.
• Unsaturated fatty acids have double bonds in the
  carbon chain.

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5.3 LIPIDS

• Saturated-carbons are joined by all single bonds
  solid _at_ room temp.
• Ex animal fats (bacon fat, etc.), cheeses,
  butter
• not healthy (raise cholesterol)
• Unsaturated (mono or poly)
• 2 carbons are joined by a double bond
• Usu. Liquid _at_ room temp.
• Derived from plants or fish
• Ex olive oil, nuts, fish oils
• Healthier fats
• Polyunsaturated-carbons have many double bonds

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Saturated Fats
Unsaturated Fats
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Saturated Fat
Unsaturated Fat
http//faculty.clintoncc.suny.edu/faculty/michael.
gregory/files/bio20101/bio2010120lectures/bioch
emistry/biochemi.htm
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5.3 STEROIDS

• Steriod - Lipid molecule with 4 fused carbon
  rings.
• Different functional groups attach to rings for
  different results.
• Ex Testosterone vs. Estrogen (HORMONES)
  Cortisol, Adrenaline
• Act as chemical signals or messengers to cells.
• Cholesterol in cell membranes. Over abundance
  can clog arteries.

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5.3 Phospholipids

• PHOSPHOLIPIDS - TWO Fatty Acids joined by a
  Molecule of Glycerol. 
• Called a LIPID BILAYER and forms a barrier
  between the inside and outside of the Cell.