Transcript FATS = LIPIDS - Wild about Bio

ARE LIPIDS BAD
FOR US?
GOOD VS. BAD
Lipids are a diverse group of
hydrophobic molecules
• Lipids are the one class of large biological
molecules that do not form polymers
• All lipids contain large chains of nonpolar
hydrocarbons (chains of carbon and hydrogen)
• Lipids are hydrophobic and water insoluble
• The most biologically important lipids are fats
(triglycerides) , phospholipids, and steroids
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Fats
• Fats are constructed from two types of smaller molecules:
glycerol and fatty acids
• Glycerol is a three-carbon alcohol with a hydroxyl group attached
to each carbon
• A fatty acid consists of a carboxyl group (COOH) attached to a
long carbon skeleton
Fat molecule
(triacylglycerol)
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• Saturated fatty acids
have the maximum
number of hydrogen
atoms possible and no
double bonds
• Unsaturated fatty acids
have one or more
double bonds
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
• Saturated fats are solid at room temperature
• Most animal fats are saturated
• Found in soaps, candles, lotion, creams, etc
• Unsaturated fats or oils are liquid at room
temperature
• Plant fats and fish fats are usually unsaturated
• Found in avocado, almonds, macadamia nuts,
etc
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FATS
• Stored as adipose tissue under skin, around
kidneys, within abdomen, etc
• Long term energy source/long term energy
storage
• Provides insulation, and protection around
organs
Phospholipids
• In a phospholipid, two
fatty acids and a
phosphate group are
attached to glycerol
• The two fatty acid tails
are hydrophobic, but
the phosphate group
and its attachments
form a hydrophilic
head
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Fig. 5-14
Hydrophilic
head
Hydrophobic
tail
WATER
WATER
• Regulates the amount of material that
goes in/out of cells.
• Provides flexibility and fluidity to cell
membrane allowing formation of
vesicles.
Steroids
• Steroids are lipids characterized by a carbon
skeleton consisting of four fused rings
• Steroids all have a 17 carbon atom skeleton
• Cholesterol, an important steroid, is a
component in animal cell membranes
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• Cholesterol:
– Insoluble in blood so carried by lipoproteins
– HDL = good cholesterol, picks up cholesterol
and takes to liver
– LDL = bad cholesterol, forms plaque in
arteries
State three functions of lipids
Compare the use of carbohydrates
and lipids in energy storage