1 Chapter 15 Lipids 15.6 Steroids: Cholesterol, and Steroid Hormones Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings CH 3 CH 3 CH 3 CH 3 HO CH 3
Jan 04, 2016
1
Chapter 15 Lipids
15.6 Steroids: Cholesterol, and Steroid
Hormones
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
CH3
CH3CH3
CH3
HO
CH3
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Steroid Nucleus
A steroid nucleus consists of
• 3 cyclohexane rings.
• 1 cyclopentane ring.
• no fatty acids.
steroid nucleus
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Cholesterol
Cholesterol• is the most abundant steroid in the body.
• has methyl CH3- groups, alkyl chain, and -OH attached to the steroid nucleus.
CH3
CH3CH3
CH3
HO
CH3
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Cholesterol in the Body
Cholesterol • 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
A normal, open artery.
5
Cholesterol in Foods
Cholesterol• is considered
elevated if plasma cholesterol exceeds 200 mg/dL.
• is synthesized in the liver and obtained from foods.
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Learning Check
Match the components of the cholesterol molecule with
the following:
___ carbon chain ___hydroxyl group
___ steroid nucleus ___methyl group
CH3
CH3CH3
CH3
HO
CH3
AC
B
D
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Solution
Match the components of the cholesterol molecule with
the following:
_D carbon chain _A_hydroxyl group
_C steroid nucleus _B_methyl group
CH3
CH3CH3
CH3
HO
CH3
AC
B
D
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Lipoproteins
Lipoproteins• combine lipids
with proteins and phospholipids.
• are soluble in water because the surface consists of polar lipids.
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Types of Lipoproteins
Lipoproteins• differ in density, composition, and function.• include low-density lipoprotein (LDLs) and high-density
lipoprotein (HDLs).
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Transport of Lipoproteins in the Body
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Steroid Hormones
Steroid hormones are• chemical messengers in cells.• sex hormones.
Androgens in males (testosterone)
Estrogens in females (estradiol)• Adrenocortical hormones from adrenal glands.
mineralocorticoids (electrolyte balance)
glucocorticoids regulate glucose level
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Steroid Hormones
Steroid hormones• are produced from
cholesterol.
• include sex hormones such as androgens (testosterone) in males and estrogens (estradiol) in females.
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Adrenal Corticosteroids
Steroid hormones called adrenal corticosteroids • 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.
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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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Adrenal Corticosteroids
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Learning Check
Identify each lipid as
(1) fatty acid (2) steroid (3) triacylglycerol.
A. Cholesterol
B. Stearic acid
C. Glyceryl tristearate
D. Estradiol
E. Contains no fatty acids.
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Solution
Identify each lipid as:
(1) fatty acid (2) steroid (3) triacylglycerol
A. 2 Cholesterol
B. 1 Stearic acid
C. 3 Glyceryl tristearate
D. 2 Estradiol
E. 2 Contains no fatty acids.
.