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VIDEO LECTURE 2 LIPIDS CLASSIFICATION& FUNCTIONS

VIDEO LECTURE 2 LIPIDS CLASSIFICATION& FUNCTIONS. Spingosine+fatty acid= ceramide Ceramide plus a phosphocholine group constitutes a sphingomyelin. C erebrosides. These are the simplest spingogycolipids

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VIDEO LECTURE 2 LIPIDS CLASSIFICATION& FUNCTIONS

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  1. VIDEO LECTURE 2 LIPIDSCLASSIFICATION& FUNCTIONS

  2. Spingosine+fatty acid=ceramide Ceramide plus a phosphocholine group constitutes a sphingomyelin

  3. Cerebrosides • These are the simplest spingogycolipids • They consist of a ceramide with a single sugar residue at the 1-hydroxyl moiety. The sugar residue can be either glucose or galactose • Galactosylceramide is the principal glycosphingolipidin brain tissue.Glucosylceramide is found at low levels in animal cells such as the spleen, erythrocytes.

  4. Cerebroside structure

  5. Gangliosides • A ganglioside is a molecule composed of a glycosphingolipid (ceramide and oligosaccharide) with one or more sialic acids (e.g. n-acetylneuraminic acid, NANA) linked on the sugar chain • The oligosaccharide groups on gangliosides extend well beyond the surfaces of the cell membranes, and act as distinguishing surface markers that can serve as specific determinants in cellular recognition and cell-to-cell communication. These carbohydrate head groups also act as specific receptors for certain pituitaryglycoproteinhormones and certain bacterial protein toxins such as cholera toxin.

  6. Structure of Ganglioside

  7. STEROIDS • Steroids are lipids containing a steroid nucleus (core structure) • The steroid nucleus is a fused ring system consisting of three cyclohexane rings and one cyclopentane ring • The rings are designated A, B, C and D • Attachment of different groups to the core steroid structure leads to a wide variety of steroid compounds, including cholesterol, bile salts and steroid hormones

  8. CHOLESTEROL • Cholesterol is the highly studied small molecule in biology. Thirteen Nobel Prizes have been awarded to scientists who devoted major parts of their careers to cholesterol • Cholesterol is the most abundant steroid in animals • Plants have very small amounts (but have related compounds) • It’s a major component of cell membranes, and affects the fluidity of the membrane due to its bulky structure • It is a precursor for biosynthesis of many other steroids • Cholesterol is called a sterol because it contains an alcohol group • We can obtain cholesterol from our diet (animal products), but our liver can also synthesize all the cholesterol that we need • The liver synthesizes more cholesterol when dietary intake is low • Excessive blood cholesterol is associated with atherosclerosis and formation of gallstones

  9. STRUCTURE OF CHOLESTEROL

  10. CHOLESTEROL IS THE BIOSYNTHETIC SOURCE OF ALL STEROIDS

  11. CHOLESTEROL IS THE BIOSYNTHETIC SOURCE OF ALL STEROID HORMONES • Five major classes of hormones • Progestins (regulate events during pregnancy and are precursors to all other steroid hormones) • Androgens (male sexual characteristic development and maintenance) • Estrogens (female sexual characteristics development and maintenance) • Glucocorticoids (promote gluconeogenesis, and in certain doses suppress inflammation rxns) • Mineralocorticoids (regulate ion balance in kidney)

  12. Bile salts • Bile acids and bile salts are synthesized from cholesterol in the liver They are stored in the gall bladder and released into the upper small intestine to help break down fats and oils (like soaps)by the process called emulsification.

  13. The Structure and Function of the Plasma Membrane • Plasma membrane act as barriers between cells and surroundings. • In eukaryotes they divide the internal space in to discrete compartments to segregate processes. • They are central to biological energy conservation and cell to cell communication. • Membranes are flexible, self sealing and selectively permeable.

  14. COMPOSITION • Membranes are selectively permeable which allows necessary molecules to cross in and waste molecules to come out of the cell. • Consist of lipids, proteins and carbohydrates, the phospholipids and sterols form the bilayer • The nonpolar regions of lipid molecules face each other at the core of the bilayer and their polar head groups face outward. • Major lipids are phospholipid which is amphipathic , contain both hydrophobic and hydrophilic region.

  15. COMPOSITION • .

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