VIII.  Fats and Lipids

A.  Functions

1.  common feature is low solubility in water (they are non-polar, hydrophobic molecules)

2.  waxy cuticle

3.  cell membrane

4.  fat droplets

5.  How do insoluble lipids move through the body?

B.  Fats

1.  Intro:  fats store more energy than carbohydrates and proteins (per gram)

a.  basic structure

b.  Why does water reject the tails?

2. Structure

a.  fats have 3 fatty acid (carboxylic acid) tails

b.  tails joined to glycerol backbone

c.  joined by ester linkage

 
 
 
 

3.  Synthesis of fats

a.  glycerol joins to 3 fatty acid tails
 
 

b.  can have different types of fatty acid tails
 
 

4.  Variations in fats

a.  fats vary in length of fatty acid tail

b.  fats vary in type of fatty acid tail (# of double bonds)

5.  Saturated vs.  Unsaturated fats

a.  unsaturated fats contain double bonds

b.  saturated fats do not (all single bonds)

c.  Why do saturated fats cause heart disease?

d.  How can I avoid saturated fats?

e.  measuring saturation:  the iodine number

6.  Liquid vs. Solid fats

a.  saturation determines melting point

b.  C=C double bond cause the tails to kink...

c.  all single bonds...

d.  When butter melts, does it gain double bonds?

e.  Does tail length matter?

7.  Saturating a fat

a.  hydrogenation

b.  trans- fatty acids

C.  Steroids

1.  Structure of Steroids

2.  Variations in steroids

a. general structure

b.  cholesterol

c.  vitamin D

d.  What is an anabolic steroid?

e.  Why does high cholesterol promote heart disease?

f.  What's all this I hear about HDL and LDL cholesterol?

g.  How can I keep my blood cholesterol down?

D.  Emulsifiers

1.  amphipathic molecules

2.  lecithin structure

E.  The trouble with fat

1.  Fat stores energy

a.  compare to carbohydrates and proteins

b.  Why do we store excess energy as fat?

2.  Fat makes food taste good

a.

b.

c.

d.

e.

3.  fats are used to cook food because

a.

b.

c.

d.

4.  Fats can deteriorate over time (react with oxygen)

a.  most easily oxidized fats are:

b.  "hydrogenated to preserve freshness"

c.  some preservatives prevent the oxidation of fats

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