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3.8 Lipids include fats, which are mostly energy-storage molecules. These compounds are composed largely of carbon and hydrogen They are not true polymers They are grouped together because they do not mix with water. Figure 3.8A. They are also called triglycerides - PowerPoint PPT Presentation
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Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• These compounds are composed largely of carbon and hydrogen
– They are not true polymers
– They are grouped together because they do not mix with water
3.8 Lipids include fats, which are mostly energy-storage molecules
Figure 3.8A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Fats are lipids whose main function is energy storage
– They are also called triglycerides
• A triglyceride molecule consists of one glycerol molecule linked to three fatty acids
Figure 3.8B
Fatty acid
LE 5-11b
Ester linkage
Fat molecule (triacylglycerol)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The fatty acids of unsaturated fats (plant oils) contain double bonds
– These prevent them from solidifying at room temperature
• Saturated fats (lard) lack double bonds
– They are solid at room temperature
Figure 3.8C
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Fatty acids vary in length (number of carbons) and in the number and locations of double bonds
• Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds
• Unsaturated fatty acids have one or more double bonds
• The major function of fats is energy storage
LE 5-12a
Saturated fat and fatty acid.
Stearic acid
LE 5-12b
Unsaturated fat and fatty acid.
Oleic acid
cis double bondcauses bending
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Fats made from saturated fatty acids are called saturated fats
• Most animal fats are saturated
• Saturated fats are solid at room temperature
• A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Phospholipids are a major component of cell membranes
• Waxes form waterproof coatings
• Steroids are often hormones
3.9 Phospholipids, waxes, and steroids are lipids with a variety of functions
Figure 3.9
LE 5-13
Structural formula Space-filling model Phospholipid symbol
Hydrophilichead
Hydrophobictails
Fatty acids
Choline
Phosphate
Glycerol
Hyd
rop
ho
bic
tai
lsH
ydr o
ph
ilic
hea
d
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Anabolic steroids are usually synthetic variants of testosterone
• Use of these substances can cause serious health problems
3.10 Connection: Anabolic steroids and related substances pose health risks
Figure 3.10
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Paper Lipid Synthesis Activity: Using the paper folding diagram for lipid, do the following…
1. What two compounds are needed to synthesize a lipid?
2. How many carbon atoms does glycerol contain?
3. Place an asterisk(s) (*) on the glycerol molecule to indicate the location where a dehydration synthesis could occur to synthesis a triglyceride.
4. How many fatty acid molecules are found on the folding diagram? Number each fatty acid molecule on the paper. Identify each as a saturated or unsaturated fatty acid.
5. How does cholesterol’s structure differ from a triglyderide?
6. What would need to draw on the folding diagram if you wanted to make a phospholipid?
If time permits, construct (3) additional questions and answer them.
