Lipit

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LIPIT
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LIPIDS
Not polymers
Comprised almost exclusively of C and H
Nonpolar bonds  no H-bonding
Generally interact poorly with water
Hydrophobic
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LIPIDS
Key roles of lipids
Energy storage
Insulation
Membrane components
Cell communication
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LIPIDS
Major classes of lipids
Fats and oils
Phospholipids
Steroids
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LIPIDS
Fats and oils
“Triacylglycerols” or “triglycerides”
Not polymers
Assembled from smaller
molecules through
condensation reactions
Glycerol
Three fatty acids
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LIPIDS
Fats and oils
Fatty acids contain long carbon skeletons
Generally 16 – 18 carbons
These carbon skeletons may contain only single bonds
“Saturated”
These skeletons may
contain double bonds
“Unsaturated”
“Polyunsaturated”
Cause chain to bend
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LIPIDS
Fats and oils
Saturated fats
Present in fatty meats, dairy products, coconut oil, etc.
Possess only single bonds in fatty acid tails
Molecules can pack together tightly
Solid at room temperature
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LIPIDS
Fats and oils
Unsaturated fats (oils)
Present in most plant and fish oils, etc.
Possess double bonds in fatty acid tails
Molecules cannot pack together as tightly
Generally liquid at room temperature
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LIPIDS
Phospholipids
Similar to fats
Glycerol
2 fatty acids
Phosphate
(Inositol,
choline, etc.)
Amphipathic
Hydrophilic region
Hydrophobic region
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LIPIDS
Phospholipids
Aggregate in water-rich environments
Micelles
Phospholipid bilayers
Key components of cell membranes
Hydrophobic regions are “hidden” from water
Hydrophilic regions are in contact with water
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LIPIDS
Cholesterol
Steroid
Amphipathic
Membrane antifreeze
Prevents membrane solidification at low temperatures
Precursor for all steroid hormones
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LIPIDS
Steroid hormones
Synthesized from cholesterol
Involved in a variety of body functions
e.g., Development
e.g., Reproduction
e.g., Salt regulation
e.g., Sugar biosynthesis
e.g., Water regulation
etc.
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LIPIDS
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REFERENCES
Campbell, Neil A. and Reese, Jane B. Biology, 7th edition. Pearson Education, Inc. 2005.
Campbell, Neil A., Reese, Jane B., Taylor, Martha R., and Simon, Eric J. Biology, Concepts and Connections, 5th edition. Pearson Education, Inc. 2006.
Nester, Eugene W., Anderson, Denise G., Roberts, C. Evans Jr., and Nester, Martha T. Microbiology, A Human Perspective, 5th edition. McGraw-Hill Companies, Inc. 2007.
Limson, Janice. 2002. http://www.scienceinafrica.co.za/2002/june/lactose.htm