BIOCHEM 4511 Study Guide - Midterm Guide: Nucleic Acid Double Helix, Isoelectric Point, Purine
4 Oct 2018
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Important concepts of water, ph, and buffer lectures (chapter 2) Water is polar- electronegativity difference between o (-0. 66e) and h (+0. 33e) Can be both a hydrogen bond donor (donates proton) and acceptor (provides lone pair) Tetrahedral geometry- may form up to 4 h-bonds. Serves as both an acid and a base. Hydrogen bonding of water to itself and other common biological functional groups: Liquid water- continuous change in h-bonds between molecules. Hydroxyl-hydroxyl, hydroxyl-carbonyl, amide-carbonyl, amide-hydroxyl, and amide-imidazole nitrogen. 90% of h-bonds in proteins are linear (stronger) H-bond strength: 20 kj*mol-1 = 5 kcal*mol-1. Determine whether a compound is hydrophilic, hydrophobic, or amphipathic and predict whether a molecule would be soluble in water or not. Hydrophilic: water loving molecule forms favorable interaction with water and dissolves well. Hydrophobic: water fearing molecule does not make favorable interactions with water and does not dissolve well. Amphipathic: part hydrophilic and part hydrophobic; molecules with localized polar and nonpolar components; ex.
