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  • L-Amino acid
  • The Fischer projection of an L-amino acid has the amino group on the left when the carbon chain is vertical with the carboxyl group at the top FIG
  • Lactam
  • A cyclic amide
  • Lactone
  • A cyclic ester
  • Lactose
  • Milk sugar; a disaccharide formed by a β-glycosidic linkage between C-4 of glucose and C-1 of galactose.
  • Lagging Strand
  • In DNA replication, the strand that grows away from the replication fork.
  • LDA
  • Abbreviation for lithium diisopropylamide LiN[CH(CH3)2]2. LDA is a strong, sterically hindered base
  • Le Chatelier's principle
  • A reaction at equilibrium responds to any stress imposed on it by shifting the equilibrium in the direction that minimizes the stress.
  • Leading strand
  • In DNA replication, the strand that grows toward the replication fork.
  • Leaving group
  • The group, normally a halide ion, that is lost from carbon in a nucleophilic substitution or elimination.
  • Lewis acid
  • see acid. LINK
  • Lewis acid/Lewis base complex
  • The species that results by covalent bond formation between a Lewis acid and a Lewis base .
  • Lewis base
  • see base. LINK
  • Lewis structure
  • A chemical formula in which electrons are represented by dots. Two dots (or a line) between two atoms represent a covalent bond in a Lewis structure. Unshared electrons are explicitly shown, and stable Lewis structures are those in which the octet rule is satisfied.
  • Ligand
  • An atom or group attached to another atom, especially when the other atom is a metal
  • Lindlar catalyst
  • A catalyst for the hydrogenation of alkynes to cis-alkenes. It is composed of palladium, which has been “poisoned” with lead(II) acetate and quinoline, supported on calcium carbonate.
  • linear
  • A common geometry around an atom with the electron domains/groups (bonds or lone pairs) lying all in a straight line with bond angles of approximately 180 degrees.  Commonly found with an sp hybridized atom, such as the carbons in ethyne.
  • Linear polymer
  • A polymer in which the chain of repeating units is not branched.
  • Lipid bilayer
  • Arrangement of two layers of phospholipids that constitutes cell membranes. The polar termini are located at the inner and outer membrane-water interfaces, and the lipophilic hydrocarbon tails cluster on the inside.
  • Lipids
  • Biologically important natural products characterized by high solubility in nonpolar organic solvents
  • Lipophilic
  • Literally, “fat-loving”; synonymous in practice with hydrophobic.
  • Living polymer
  • A polymer that retains active sites capable of further reaction on addition of more monomer
  • Locant
  • In IUPAC nomenclature, a prefix that designates the atom that is associated with a particular structural unit. The locant is most often a number, and the structural unit is usually an attached substituent as in 2-chlorobutane.
  • London force
  • See induced-dipole/induced-dipole attraction LINK
  • Low-density lipoprotein (LDL)
  • A protein which carries cholesterol from the liver through the blood to the tissues. Elevated LDL levels are a risk factor for heart disease; LDL is often called “bad cholesterol.”
  • LUMO
  • The orbital of lowest energy that contains none of a molecule’s electrons; the lowest unoccupied molecular orbital
Department of Chemistry & Chemical Biology