Microbiology terms - N
- natural killer (NK) cell
- A specialized lymphocyte that recognizes and destroys foreign cells or
infected host cells in a nonspecific manner.
- necrosis
- Damage of living tissues due to infection or injury.
- nicotinamide adenine dinucleotide (NAD)
- An important coenzyme, functioning as a hydrogen carrier in a wide range of
redox reactions; the H is carried on the nicotinamide residue. The oxidized
form of the coenzyme is written NAD+, the reduced form as NADH (or
NADH+H+)
- nicotinamide adenine dinucleotide phosphate (NADP)
- An important coenzyme, functioning as a hydrogen carrier in a wide range of
redox reactions; the H is carried on the nicotinamide residue. The oxidized
form of the coenzyme is written NADP+, the reduced form as NADPH.
Many oxidoreductases are specific for either NAD or NADP, although
some can function with either. As a broad generalization, NADP is more
commonly associated with biosynthetic reactions, NAD with catabolic and
energy-yielding reactions.
- nitrification
- The conversion of ammonia (NH3) to nitrate (NO3-).
- nitrifying bacteria
- Chemolithotrophs capable of carrying out the transformations from NH3 to
NO2- or NO2- to NO3-.
- nitrogenase
- The enzyme complex catalyzing the reaction of nitrogen fixation.
- nitrogen fixation
- Reduction of dinitrogen gas (N2) to ammonia (NH3) by the enzyme
nitrogenase.
- nodule (root nodule)
- A tumorlike structure produced by the roots of symbiotic nitrogen-fixing
plants. Contains the nitrogen-fixing microbial component of the symbiosis.
- nomenclature
- The system of naming things (e.g. organisms).
- nonpolar
- Possessing hydrophobic (water repelling) characteristics and not easily
dissolved in water.
- nonsense mutation
- A mutation that changes a sense codon into one which does not code for an
amino acid.
- nonsulfur purple bacteria
- A group of phototrophic prokaryotes containing bacteriachlorophylls a or b
which grow best as photohetertrophs and have a relatively low tolerance for
hydrogen sulfide (H2O).
- northern blot
- Hybridization of a single strand of nucleic acid (DNA or RNA) to RNA
fragments immobilized on a filter. Compare with Southern and western blot.
- nosocomial infection
- Hospital-acquired infection.
- nucleic acid
- A polymer of nucleotides, see also DNA and RNA.
- nucleic acid probe
- A strand of nucleic acid which can be labeled and used to hybridize to a
complementary molecule from a mixture of other nucleic acids. In clinical
microbiology, short oligonucleotide of unique sequences used as
hybridization probes for identifying pathogens.
- nucleoid
- The aggregated mass of DNA that makes up the chromosome of
prokaryotic cells.
- nucleoside
- A nucleotide without the phosphate group.
- nucleotide
- A monomeric unit of nucleic acid, consisting of a sugar (ribose), a
phosphate, and a nitrogenous base.
- nucleus
- A membrane-enclosed structure containing the genetic material (DNA)
organized in chromosomes.
- numerical taxonomy
- The groupig by numerical methods of taxonomic units into taxa based on
their character states.
- nutrient
- A substance taken by a cell from its environment and used in catabolic or
anabolic ractions.
- nutrient agar
- The solid version of nutrient broth supplemented with agar.
- nutrient broth
- A general-purpose liquid basal medium composed of e.g. beef extract and
peptone, which allows many types of microorganisms to grow.
Compiled by Tsute Chen, Converted by Ben Hoyt