-
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
-
Polar bonds
bonds with a difference in electronegatively giving rise to partial positive and partial negative charges
-
Hydrogen Bond
electrostatic attraction between the oxygen atom of one molecule and the hydrogen of another
-
Hydrogen Acceptor
usually oxygen and nitrogen, an electronegative atom
-
Hydrogen Donor
hydrogen atom covalently bonded to another electronegative atom
-
Hydrocarbons
compounds that contain only carbon and hydrogen, which are nonpolar and are typically not soluble in water
-
Hydrophobic Effect
the driving force for the formation of biological lipid membranes where hydrophobic molecules consequently cluster, releasing water from constraint
-
Amphipathic Compounds
molecule containing both polar (hydrophilic) and nonpolar (hydrophobic) portions; example: fatty acid
-
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
-
Acid
proton (hydrogen ion) donor
-
Base
proton (hydrogen ion) acceptor
-
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
-
Ion product constant for water
Kw, where the concentration of water has been included in its value
-
pKa
more convenient numerical measure of acid strength, the smaller its value, the stronger the acid
-
Titration
experiment in which measured amounts of base are added to a measured amount of acid
-
Equivalence Point
the point of titration at which the acid is exactly neutralized
-
Inflection Point
reached in the titration curve when the pH equals the pKa of acetic acid
-
Monoprotic Acids
release one hydrogen ion and have a sking Ka and pKa value
-
Diprotic Acids
release two hydrogen ions and have two Ka and pKa values
-
Polyprotic Acids
release more than two hydrogen ions, and can have several Ka and pKa values
-
When the pH of a solution is less than the pKa of an acid, the ________ form predominates
protonated
-
When the pH of a solution is greater than the pKa of an acid, the _________ form predominates
deprotonated
-
Buffer solution
resists change in pH when small or moderate amounts of a strong acid or strong base are added
-
What are the two main buffering systems in living organism?
1. H2PO4-/ HPO42- : cells
2. H2CO3/ HCO3- : blood
|
|