Bio2205

• Lipids


  Large molecules that are not soluble in water, but are soluble in nonpolar solvents
• Common lipids


  • Fats
  • Steroids
  • Fat soluble vitamins
• Lipids


  • Important part of almost all cells
  • Found in cell membranes and brain and nervous tissue
  • Long-term energy storage in the body
  • Serve as insulation of body's organs against temperature change and shock
• Fats and oils generally provide 9 Cal/g of energy in our diet, and can be converted to glucose
• Classes of lipids


  • Triglycerides
  • Phosphoglycerides
  • Sphingolipids
  • Glycolipids
  • Steroids
  • Fat Soluble Vitamins
• The first four classes of lipids have at least one fatty acid
• Fatty acids


  Long hydrocarbon chains with a carboxyl group at one end
• Types of fatty acids

  • Saturated
  • Monounsaturated (cis)
  • Monounsaturated (trans)
  • Polyunsaturated (2 double bonds)
  • Polyunsaturated (3 double bonds)
• Saturated fatty acids


  • Stack together very easily, so they are solid at room temperature
  • Raise cholesterol levels in the blood
• Cis unsaturated fatty acids

  • Do not stack together well, so they tend to be liquids at room temperature
  • Prone to oxidation and becoming rancid
• Trans fatty acids


  • Stack together well like saturated fatty acids
  • Raise levels of low density lipoproteins (LDL) in the blood, leading to heart disease
• Hydrogenation


  Converts cis double bonds to trans double bonds
• Glycerol


  A 3-carbon alcohol that forms the backbone of triglycerides
• Triglycerides with 3 unsaturated fatty acids in the cis configuration are liquid at room temperature
• Saponification


  Hydrolysis of a triglyceride with a strong base to produce glycerol and 3 salts of fatty acids

  
• Soap


  The salt of a fatty acid, with both a water-loving (hydrophilic) head and a water-hating (hydrophobic) tail
• Soap is able to wash away oil from skin or dishes due to its amphiphilic nature
• Micelle


  An aggregate of soap molecules with the nonpolar tails in the center and the polar heads on the surface, allowing it to surround and remove nonpolar substances
• Types of complex lipids


  • Glycolipids
  • Phosphoglycerides
  • Sphingolipids
• Glycolipids, sphingolipids, and phosphoglycerides

  • Have two hydrophobic "tails" and a hydrophilic head
  • Form the "lipid bilayer" of cell membranes
• Glycolipids are found in brain and nervous tissue
• Sphingolipids form the myelin sheath which protects and insulates nerve tissue
• Steroid examples


  • Cortisone
  • Cholesterol
  • Testosterone
  • Estrone
• Carbohydrates make up a major part of our diet and of all organic matter on Earth
• Carbohydrates


  Contain carbon, hydrogen, and oxygen in a 1:2:1 ratio
• Photosynthesis


  Carbon dioxide + Water + Energy -> Carbohydrate
• Functions of carbohydrates in animals/humans

  • Energy source
  • Structural components
  • Provide 4 Cal/g of energy
• Functions of carbohydrates in plants

  • Energy storage
  • Structural components
  • Photosynthesis
• Types of carbohydrates


  • Monosaccharides
  • Disaccharides
  • Polysaccharides

  
• Monosaccharide examples


  • Glucose
  • Fructose
  • Galactose
• Glycosidic linkage


  Bond formed between the hemiacetal group of one monosaccharide and the hydroxyl group of another
• Glucose is a reducing sugar
• Alpha and beta forms of glucose


  • Differ in the position of one hydroxyl group
  • Alpha form is found in starch, which we can digest
  • Beta form is found in cellulose, which we cannot digest

  
• Alpha and beta forms of galactose


  Differ in the position of one hydroxyl group
• Galactose is a monosaccharide sugar
• Ring Structures


  • C-C-C-C-O-C-CH2OH-H-OH-H-H-H-OH-H-OH-O-H
• α and β forms of glucose


  Differ only in the position of one hydroxyl group
• Glucose is a monosaccharide sugar
• Starch foods like pasta, bread, and rice contain the α form of glucose, which we can digest. The β form is found in wood and cellulose which we cannot digest.
• α and β forms of galactose


  Differ only in the position of one hydroxyl group