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Lipids

Lipids. Phospholipids Steroids and Cholesterol Plasma (Cell)Membranes. Phosphoglycerides. Most abundant lipids in cell membranes Control cell permeability FATTY ACID FATTY ACID . glycerol. PO 4. Amino alcohol. Lecithin. Abundant in brain and nerve tissues

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Lipids

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  1. Lipids Phospholipids Steroids and Cholesterol Plasma (Cell)Membranes

  2. Phosphoglycerides • Most abundant lipids in cell membranes • Control cell permeability FATTY ACID FATTY ACID glycerol PO4 Amino alcohol

  3. Lecithin • Abundant in brain and nerve tissues • Found in egg yolk, what germ, yeast

  4. Sphingolipids Esters of an 18-carbon alcohol sphingosine FATTY ACID sphingosine PO4 Amino alcohol

  5. Sphingomyelin Found in the myelin sheath CH3(CH2)12CH=CH –CH–OH O sphingosine‖ fatty acid CH–NH –C –(CH2)14CH3 O ‖+ CH2 –O –P –O –CH2CH2 –N–(CH3)3 ‖ O– choline

  6. Steroids • Steroid nucleus • 3 cyclohexane rings • 1 cyclopentane ring steroid nucleus

  7. Cholesterol • Most abundant steroid in the body • Add methyl CH3- groups, alkyl chain, and -OH to steroid nucleus

  8. Cholesterol in the Body • Cellular membranes • Myelin sheath, brain, and nerve tissue • Bile salts • Hormones • Vitamin D

  9. Bile Salts • Synthesized in the liver from cholesterol • Stored in the gallbladder • Secreted into small intestine • Mix with fats to break them part • Emsulsify fat particles

  10. Example of a Bile Salt

  11. Steroid Hormones • Chemical messengers in cells • Sex hormones Androgens in males (testosterone) Estrogens in females (estradiol) • Adrenocorticosteroids from adrenal glands mineralocorticoids (electrolyte balance) glucocorticoids regulate glucose level

  12. Sex Hormones

  13. Plasma Membranes • Surround cells • Lipid bilayer pf phospholipids • Nonpolar hydrocarbon tails in center • Polar (hydrophilic) sections on outside • Some unsaturated fatty acids give flexibility • Keep aqueous contents inside • Allow certain biochemicals to pass through

  14. Diagram of a Plasma Membrane Polar sections Nonpolar tails

  15. Other Structures in Membranes • Cholesterol molecules add strength • Glycolipids on surface communicate with other cells • Proteins embedded in bilayer move certain substances (water, K+, Cl-, HCO3-) across the cell membrane • Proteins on surface act as receptors for hormones and other biochemicals

  16. Learning Check PL1 Identify each lipid as: (1) phospholipid (2) steroid (3) triglyceride (4) sphingolipid A. Cholesterol • Glycerol, 2 fatty acids, phosphate, and choline • Glyceryl tristearate • Sphingosine, fatty acid, phosphate, and choline • Estradiol • Bile salts • Most of plasma membranes

  17. Solution PL1 A. 2 steroid B. phospholipid C. 3 triglyceride D. 4 sphingolipid E. 2 steroid F. 2 steroid G. 1 phospholipid

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