|
nicotine adenine dinucleotide:
see NAD+
nicotine adenine dinucleotide phosphate:
see NADP+
Nitella:
Green algae with giant multinucleated cells. Used in studies
of plant physiology and actin-based cytoplasmic streaming.
nitrogen cycle:
The natural circulation of nitrogen between organic molecules
in living organisms and inorganic molecules in the soil.
nitrogen fixation:
Biochemical process performed by specific bacteria that reduces
atmospheric nitrogen (N2) to ammonia and
hence into various nitrogen-containing metabolites.
nitrogenase complex:
Complex of enzymes in nitrogen-fixing bacteria that catalyzes
the reduction of atmospheric N2 to ammonia.
nm:
see nanometer
NMR (nuclear magnetic resonance):
Resonant absorption of electromagnetic radiation at a specific
frequency by atomic nuclei in a magnetic field, due to flipping
of the orientation of their magnetic dipole moments. The NMR spectrum
provides information about the chemical environment of the nuclei.
Two-dimensional NMR is used widely to determine the three-dimensional
structure of small proteins.
noncovalent bond:
Chemical bond in which, in contrast to a covalent bond, no electrons
are shared. Noncovalent bonds are relatively weak, but they
can sum together to produce strong, highly specific interactions
between molecules.
nonpolar molecule (apolar molecule):
Molecule lacking any asymmetric accumulation of positive or
negative charge; such molecules are generally insoluble in water.
Northern blotting:
Technique in which RNA fragments separated by electro-phoresis
are immobilized on a paper sheet; a specific molecule is then
detected with a labeled nucleic acid probe.
|
