Chapter 2

  1. Water
    • -principle solvent if living cells, plays a major role in determining the properties of macromolecules
    • -significantly higher boiling and freezing temperatures
    • -higher heat of vaporization
    • -intramolecular attraction/ 2 electric dipoles
  2. Polar bonds
    bonds with a difference in electronegatively giving rise to partial positive and partial negative charges
  3. Hydrogen Bond
    electrostatic attraction between the oxygen atom of one molecule and the hydrogen of another
  4. Hydrogen Acceptor
    usually oxygen and nitrogen, an electronegative atom
  5. Hydrogen Donor
    hydrogen atom covalently bonded to another electronegative atom
  6. Hydrocarbons
    compounds that contain only carbon and hydrogen, which are nonpolar and are typically not soluble in water
  7. Hydrophobic Effect
    the driving force for the formation of biological lipid membranes where hydrophobic molecules consequently cluster, releasing water from constraint
  8. Amphipathic Compounds
    molecule containing both polar (hydrophilic) and nonpolar (hydrophobic) portions; example: fatty acid
  9. Micelles
    structures formed from an amphipathic molecule in the presence of water; the polar head groups are in contact with the aqueous environment and the nonpolar tails are sequestered from the water
  10. Acid
    proton (hydrogen ion) donor
  11. Base
    proton (hydrogen ion) acceptor
  12. Acid dissociation constant
    Ka value, is a measure of the amount of hydrogen ion released when a given amount of acid is dissolved in water (the strength of the acid); the larger the value, the stronger the acid
  13. Ion product constant for water
    Kw, where the concentration of water has been included in its value
  14. pKa
    more convenient numerical measure of acid strength, the smaller its value, the stronger the acid
  15. Titration
    experiment in which measured amounts of base are added to a measured amount of acid
  16. Equivalence Point
    the point of titration at which the acid is exactly neutralized
  17. Inflection Point
    reached in the titration curve when the pH equals the pKa of acetic acid
  18. Monoprotic Acids
    release one hydrogen ion and have a sking Ka and pKa value
  19. Diprotic Acids
    release two hydrogen ions and have two Ka and pKa values
  20. Polyprotic Acids
    release more than two hydrogen ions, and can have several Ka and pKa values
  21. When the pH of a solution is less than the pKa of an acid, the ________ form predominates
  22. When the pH of a solution is greater than the pKa of an acid, the _________ form predominates
  23. Buffer solution
    resists change in pH when small or moderate amounts of a strong acid or strong base are added
  24. What are the two main buffering systems in living organism?
    1. H2PO4-/ HPO42- : cells

    2. H2CO3/ HCO3- : blood
Card Set
Chapter 2
Water: the solvent for biochemical reactions