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Compound and Derived Lipids
Glycerophospholipids are: The most abundant lipids in cell membranes. Composed of glycerol, two fatty acids, phosphate and an
amino alcohol.
Glycerol
PO4
Amino
alcohol
Glycerophospholipids
Fatty acid
Fatty acid
Phospholipids
PolarHead Glycerol Fatty Acid Tails
HydrophobicHydrophilic
Polarity of Glycerophospholipids
A glycerophospholipid has polar and nonpolar regions.
Lecithin and cephalin are glycerophospholipids: Abundant in brain and nerve tissues. Found in egg yolk, wheat germ, and yeast.
Lecithin and Cephalin
Sphingolipids are phospholipids that have an amide bond between a fatty acid and sphingosine, an 18-carbon alcohol.
Sphingolipids
Glycosphingolipids
Glycosphingolipids (cerebrosides and gangliosides) contain monosaccharides bonded to the –OH of sphingosine by a glycosidic bond.
Cerebrosides contain only one monosaccharide.
Gangliosides
Gangliosides are similar to cerebrosides, but contain two or more monosaccharides.
Lipid Diseases (Lipidoses)
In many lipid diseases, the deficiency of an enzyme causes the accumulation of glycolipids.
Steroids are: Lipids containing the steroid nucleus, which
is a fused structure of four rings. Found in cholesterol, bile salts, hormones,
and vitamin D.
Steroids
steroid nucleus
Complex ring forms Some hormones Cholesterol
Natural substance
Found in membranes
Gives membranes natural flexibility
Steroids
Steroids
Cholesterol Estradiol
Testosterone
The most abundant steroid in the body.
Contains 27 carbon atoms.
At C3 there is a –OH group; so it is an alcohol.
Composed of the steroid nucleus with methyl groups, an alkyl chain, and a hydroxyl group attached.
Precursor for adrenal corticosteroids, vitamin D and bile acids
Cholesterol
CH3
HO
CH3
CH3 CH3
CH3
Cholesterol in Foods
Cholesterol:
Is considered elevated if plasma cholesterol exceeds 200-220 mg/dL.
Is synthesized in the liver and obtained from foods.
100 g
1
100 g
100 g
100 g
100 g
100 g
1 tablespoon
1 cup
1 cup
1 tablespoon
Lipoproteins Combine lipids with proteins and phospholipids. Are soluble in water because the surface consists of
polar lipids.
Types of LipoproteinsLipoproteins:
Differ in density, composition, and function.
Include low-density lipoprotein (LDLs) and high-density lipoprotein (HDLs).
Transport of Lipoproteins in the Body
Bile Salts
Are synthesized from cholesterol and stored in the gall bladder.
Emulsify fats and oils to give a greater surface area for lipid digesting enzymes.
CH3
HO
CH3
CH3OH
C
O
N
H
CH2COO- Na+
OH
glycine, an amino acid
cholic acid, a bile acid
sodium glycocholate, a bile salt
Steroid Hormones
Steroid hormones:
Are produced from cholesterol.
Include sex hormones such as androgens (testosterone) in males and estrogens (estradiol) in females
Estradiol
Testosterone
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.
Adrenal Corticosteroids
Lipid Profile
Lipid profile includes:
1)Total lipids
2)Triglycerides
3) Cholesterol
4) HDL
5) LDL These tests must be carried out after 12-15 hrs.
fasting due the high molecular weight of lipid molecules and the prolonged digestion and metabolism.
Phospholipids
Polar group
Phospholipid Bilayer
Mic
elles
A Composite Cell
Major parts include:• Nucleus• Cytoplasm• Cell membrane
Microtubules
Flagellum
Nuclear envelope
Basal body
Chromatin
Ribosomes
Cell membrane
Mitochondrion
Cilia
Microtubules
Microtubule
Centrioles
Microvilli
Lysosomes
Nucleolus
Nucleus
Phospholipid bilayer
Smooth
Endoplasmic
reticulum
Rough
Endoplasmic
reticulum
Golgi
apparatus
Secretory
vesicles
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.
Cell Membrane
Cell membraneCell membrane
“Heads” of
phospholipid
“Tails” of
phospholipid
Fibrous proteinCarbohydrateGlycolipid
Glycoprotein
Extracellular sideof membrane
Cytoplasmic sideof membrane
Cholesterolmolecules
Globularprotein
Doublelayer of
Phospholipidmolecules
Hydrophobicfatty acid
“tail”
HydrophilicPhosphate
“head”
Fluid Mosaic Model of Cell Membranes
The lipid bilayer contains proteins, carbohydrates, and cholesterol.
The unsaturated fatty acids make cell membranes fluid-like rather than rigid.
Proteins and carbohydrates on the outer surface communicate with hormones and neurotransmitters.
Transport Through Cell Membranes
Diffusion (passive transport) moves particles from a higher to a lower concentration.
Facilitated transport uses protein channels to increase the rate of diffusion.
Active transport moves ions against a concentration gradient.
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