1. Glycerophospholipids
Glycerophospholipids are
The most abundant lipids in cell membranes.
Composed of glycerol, two fatty acids, phosphate and an amino alcohol.
Fatty acid
Glycerol
Fatty acid
PO4
Amino
alcohol

2. Glycerophospholipids Are Polar
A glycerophospholipid has
Two nonpolar fatty acid chains.
A phosphate group and a polar amino alcohol.
CH3 │
HO−CH2−CH2−N−CH HO−CH2−CH2−NH3 │
choline CH ethanolamine +
NH3
│ Amino alcohols
HO−CH2−CH−COO−
serine

3. Structure and Polarity of A Glycerophospholipid
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4. Lecithin and Cephalin Lecithin and cephalin are glycerophospholipids
Abundant in brain and nerve tissues.
Found in egg yolk, wheat germ, and yeast.
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5. Sphingolipids Sphingolipids Are similar to phospholipids.
Contain sphingosine (a long-chain amino alcohol), a fatty acid, phosphate, and a small amino alcohol.
Have polar and nonpolar regions.
fatty acid
sphingosine
PO4
amino
alcohol

6. Sphingosine Sphingosine is a long-chain unsaturated amino alcohol.
CH3−(CH2)12 −CH=CH−CH−OH │
CH−NH2
CH2−OH
sphingosine

7. Sphingolipids In sphingomyelin, a sphingolipid found in nerve cells
There is an amide bond between a fatty acid and sphingosine, an 18-carbon alcohol.
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8. Glycosphingolipids
Glycosphingolipids contain monosaccharides bonded to the –OH of sphingosine by a glycosidic bond.
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9. Glycosphingolipids (Cerebrosides)
Are sphingolipids that contain monosaccharides.
Can be a cerebroside with galactose.
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10. Glycosphingolipids (Gangliosides)
Are similar to cerebrosides, but contain two or more monosaccharides.
Are important in neurons.
Act as receptor for hormones and viruses.
Can accumulate and cause genetic diseases.

11. Gangliosides GM2 is a ganglioside
That accumulates in Tay-Sachs disease.
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12. Lipid Diseases (Lipidoses)
In many lipid diseases, the deficiency of an enzyme causes the accumulation of glycolipids.
TABLE 17.3
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13. Steroid Nucleus A steroid nucleus consists of 3 cyclohexane rings.
1 cyclopentane ring.
No fatty acids.
steroid nucleus

14. Cholesterol Cholesterol Is the most abundant steroid in the body.
Has methyl CH3- groups, alkyl chain, and -OH attached to the steroid nucleus.

15. Cholesterol in the Body
A normal, open artery.
Cholesterol in the body
Is obtained from meats, milk, and eggs.
Is synthesized in the liver.
Is needed for cell membranes, brain and nerve tissue, steroid hormones, and Vitamin D.
Clogs arteries when high levels form plaque.
An artery clogged by cholesterol plaque
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16. Cholesterol in Foods Cholesterol is
Considered elevated if plasma cholesterol exceeds 200 mg/dL.
TABLE 17.4
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17. Bile Salts Bile salts Are synthesized in the liver from cholesterol.
Are stored in the gallbladder.
Are secreted into the small intestine.
Have a polar and a nonpolar region
Mix with fats to break them part.
Emulsify fat particles to provide large surface area.

18. Bile Salts
Polar region
Nonpolar region

19. Lipoproteins Lipoproteins
Combine lipids with proteins and phospholipids.
Are soluble in water because the surface consists of polar lipids.
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20. Types of Lipoproteins Lipoproteins
Differ in density, composition, and function.
Include low-density lipoprotein (LDLs) and high-density lipoprotein (HDLs).
TABLE 17.5
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21. Transport of Lipoproteins in the Body
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22. Steroid Hormones Steroid hormones Are chemical messengers in cells.
Are produced from cholesterol.
Include sex hormones such as androgens (testosterone) in males and estrogens (estradiol) in females.
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23. Adrenal Corticosteroids
Adrenal corticosteroids are steroid hormones that
Are produced by the adrenal glands located on the top of each kidney.
Include aldosterone, which regulates electrolytes and water balance by the kidneys.
Include cortisone, a glucocorticoid, which increases blood glucose level and stimulates the synthesis of glycogen in the liver.

24. Adrenal Corticosteroids
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25. Anabolic Steroids Anabolic steroids Are derivatives of testosterone.
Are used illegally to increase muscle mass.
Have side effects including fluid retention, hair growth, sleep disturbance, and liver damage.
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26. Cell Membranes Cell membranes
Separate cellular contents from the external environment.
Consist of a lipid bilayer made of two rows of phospholipids.
Have an inner portion made of the nonpolar tails of phospholipids with the polar heads at the outer and inner surfaces.

27. Fluid Mosaic Model of Cell Membranes
The lipid bilayer
Contains proteins, carbohydrates, and cholesterol.
Has unsaturated fatty acids that make cell membranes fluid-like rather than rigid.
Has proteins and carbohydrates on the surface that communicate with hormones and neurotransmitters.

28. Fluid Mosaic Model Copyright © 2007 by Pearson Education, Inc.
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29. Transport Through Cell Membranes
The transport of substances through cell
Membranes involves
Diffusion (passive transport), which moves particles from a higher to a lower concentration.
Facilitated transport, which uses protein channels to increase the rate of diffusion.
Active transport, which moves ions against a concentration gradient.

30. Transport Pathways Through Cell Membranes
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