BIOL 110 1st Edition Lecture 10Functional Groups cont. - Functional groups form molecular units. - Groups with just C and H are nonpolar. o Small electronegativity difference C:2.5 vs H: 2.1 - Groups with C H or P bonded to O or N are polar o Large electronegative difference Polar/Nonpolar Molecules- Entire molecules also polar/nonpolar o Defined by charged separation - positive/negative charged molecules and ions always polar o separated from the neutral charge in the environment surrounding the ion - since molecules can be larger they can be polar , ex) acetone o has some polar and nonpolar groups o what is acetone use for? Nail polish remover/ paint thinner- Key concept- like interacts favorably with like o Mix and dissolve well in each other o Polar things interact favorably with polar water – beer, wine, mojitoo Nonpolar also interact favorably with nonpolar water -- gasoline and motor oilo Unlike don’t interact favorably – don’t mix  Water and cooking oil - Blood- polar - Membrane- nonpolar } all drugs must be polar to dissolve and partly nonpolar - Cell- polar Wear, noncovalent Bonding - Not ionic bonding - Doesn’t mean “not covalent” - Result of quantum mechanics/ electromagnetic force - Creates effective but reversible interactions o Means in takes much less energy to break these noncovalent bonds than ionic/covalent bonds Van Der Waals - Occurs between all atoms - Can be attractive or repulsive - All atoms attract each other via VDW attraction - Also repulse via VDWHydrogen Bonding - Only attractive and requires specific set up – not all atoms can do this- Requirement: H covalently bonded to move electronegative atom o More electronegative atom attracts shared electrons of Covalent Bonds and has a partial negative charge. ( H-bond donor) - H then has a partial positive charge - H+ end of CB can now be attracted to another electronegative atom o Electronegative atom = H bond acceptor - This forms the H bond - H- bonds are stronger than VDW attraction o Makes an important source of effective but reversible interactions between biological