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Lipids & Nucleic Acids

Lipids & Nucleic Acids. Lipids: Basic Information. Lipids are defined as groups of molecules that are insoluble in water. Fats (triglycerides), oils, waxes, and steroids. Long chains of CH 2 units Molecules are nonpolar. Phospholipids. Special types of lipid

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Lipids & Nucleic Acids

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  1. Lipids & Nucleic Acids

  2. Lipids: Basic Information • Lipids are defined as groups of molecules that are insoluble in water. • Fats (triglycerides), oils, waxes, and steroids. • Long chains of CH2 units • Molecules are nonpolar

  3. Phospholipids • Special types of lipid • form the core of all biological membranes.

  4. Types of Lipids

  5. Lipids repel water. Ex. The cuticle of plants is waxy. The waxy covering makes the plant water proof and minimizes water loss. Lipids are hydrophobic

  6. One glycerol-alcohol Three fatty acid chains Building Blocks of Lipids

  7. Fats and Oils (triglycerides) • Fats and oils consist of a glycerol molecule with three attached fatty acids (triglyceride / triglycerol). • Saturated fats - all internal carbon atoms are bonded to at least two hydrogen atoms • usually a solid at room temperature • Unsaturated fats - at least one double bond between successive carbon atoms • Polyunsaturated - contains more than one double bond • usually liquid at room temperature

  8. Fats as Energy Storage Molecules • Fats, on average, yield about 9 kcal per gram versus 4 kcal per gram for carbohydrates. • Animal fats are saturated while most plant fats are unsaturated. • Consumption of excess carbohydrates leads to conversion into starch, glycogen, or fats for future use.

  9. Triglycerides

  10. Saturated vs. unsaturated fatty acids

  11. Which fats are best? • Unsaturated with one double bond can help lower cholestrol • Examples-olive and canola • Saturated or hydrogenated are considered unhealthy and should be consumed in limited quanities

  12. Cis and Trans

  13. Hydrogenated Fats • Hydrogenation is used to add hydrogens to unsaturated fats and make them more solid. If a fat is FULLY saturated, it becomes solid, like candle wax. If it is PARTIALLY saturated (the same as partially hydrogenated) the result is a semi-solid, like margarine.

  14. Steroids • Steroid hormones are crucial substances for the proper function of the body. They mediate a wide variety of vital physiological functions ranging from anti-inflammatory agents to regulating events during pregnancy. • They are synthesized and secreted into the bloodstream by endocrine glands such as the adrenal cortex and the gonads (ovary and testis). • Skeleton made of four fused carbon rings • Cholesterol is a steroid as well as the foundation for other steroids.

  15. Long-chain fatty acid bonded to a long-chain alcohol High melting point Waterproof Resistant to degradation Why do you wax a car? Waxes

  16. Waxes

  17. Phospholipids

  18. Derived from triglycerides Glycerol backbone Two fatty acids attached instead of three Third fatty acid replaced by phosphate group The fatty acids are nonpolar and hydrophobic The phosphate group is polar and hydrophilic Molecules self arrange when placed in water Polar phosphate “heads” next to water Nonpolar fatty acid tails” overlap and exclude water Spontaneously form double layer & a sphere Phospholipids

  19. Phospholipid molecules have one end which is attracted to water while the other is repelled by it. The fatty acid end is not attracted to water and is called hydrophobic. At the other end of the molecule the phosphate group is attracted to water, it is said to be hydrophilic. Phospholipid Structure Hydrophilic Head Hydrophobic Tail

  20. Phospholipids Form Membranes

  21. Nucleic Acids

  22. Nucleic Acids • Deoxyribonucleic Acid (DNA) • Encodes information used to assemble proteins. • Ribonucleic Acid (RNA) • Reads DNA-encoded information to direct protein synthesis. Adenosine triphosphate (ATP) • Provides energy

  23. Nucleic Acid Structure • Nucleic acids are composed of long polymers of repeating subunits, nucleotides - the monomer. • five-carbon sugar • phosphate • nitrogenous base • purines • adenine and guanine • pyrimidines • cytosine, thymine, and uracil

  24. Nucleic Acid Structure • DNA exists as double-stranded molecules. • Genetic info. - coded for by the order of the nucleotides. • double helix • complementary base pairing • hydrogen bonding • base pairing: A-T, C-G • RNA exists as a single stand. • contains ribose instead of deoxyribose • contains uracil in place of thymine

  25. Nucleotides

  26. Comparison of DNA & RNA • Feature • DNA • RNA • Sugar • Deoxyribose • Ribose • Bases • Cytosine, guanine;adenine, thymine • Cytosine, guanine; • adenine, uracil • Strands • Double-stranded; Pairing across strands • Mostly single stranded • Helix • Yes • No • Function • Heredity; cellular control center • Interprets genetic info; protein synthesis • Where • Chromosomes of cell nucleus • Cell nucleus and cytoplasm

  27. Structure of DNA

  28. RNA Structure

  29. DNA  RNA Protein

  30. Other Nucleic Acids • ATP (adenosine triphosphate) is composed of adenine, ribose, and three phosphates • In cells, one phosphate bond is hydrolyzed – Yields: • The molecule ADP (adenosine diphosphate) • An inorganic phosphate molecule pi • Energy • Other energy sources used to put ADP and pi back together again

  31. ATP

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