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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Nitroblue Tetrazolium (NBT) - NMDA Receptor
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Nick
1. A break in one of the strands of double –stranded DNA. 2. To break a phosphodiester bond in one of the strands of the DNA duplex.
Nick translation
A procedure for labelling DNA with radioactive dNTPs. This is accomplished by E.coli DNA polymerase I that uses a nick as a starting point from which one strand of duplex DNA is degraded and replaced by synthesis of a new strand.
Nickase
An enzyme which cleaves one strand of a duplex.
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Nicotinamide
A constituent of the coenzymes –NAD+ and NADP+ which function as electron carriers in redox reactions and play a vital role in glycolysis, oxidative phosphorylation and many synthetic and catabolic processes.
Nicotinic acid
See niacin
Nicotinic receptors
A type of cholinergic receptor that is sensitive to nicotine
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Niemann Pick disease
A lipid storage diseases. This is of three types: Type A disease is the most common disorder characterized by a deficiency of sphingomyelinase. Type B disease is also due to deficiency of sphingomyelinase but is relatively more benign. Type C disease is associated with massive accumulation of cholesterol in lysosomes probably due to a defect in the intracellular utilization of cholesterol. There is no deficiency of sphingomyelinase.
Nif genes
Nitrogen-fixing genes found in bacteria such as Klebsiella. About 17 nif genes are organised in 8 transcription units in Klebsiella.
Ninhydrin
A chemical that reacts with amino groups of amino acids to form a purple pigment called Ruhemann’s purple. It is used in the qualitative and quantitative analysis of amino acids and proteins.
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Ninhydrin reaction
A colour reaction given by amino acids and peptides when heated with ninhydrin. This reaction is used in detecting and estimating amino acids.
Nirenberg, Marshall(b.1927)
A biochemist who conducted experiments that helped crack the genetic code. He was awarded the Nobel Prize in Physiology or Medicine in 1968.
Nitrate
The only form in which nitrogen can be used directly by plants; a component of chemical fertilisers.
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Nitric oxide (NO)
A gaseous signal molecule in plants and animals. In plants, it is involved in response to injury. In animals, it controls smooth muscle contraction.
Nitrification
A chemical process in which nitrogen in plant and animal wastes and dead remains is oxidized to nitrites and nitrates.
Nitrifying bacteria
Bacteria that convert atmospheric nitrogen to ammonia. By this method, nitrogen is incorporated into proteins and nucleic acids.
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Nitrite
A salt or ester of nitrous acid.
Nitroblue tetrazolium (NBT)
A chemical that forms a blue precipitate when alkaline phosphatase acts on certain substrates. It is therefore incorporated as an indicator in techniques that use alkaline phosphatase labels.
Nitrocellulose; cellulose nitrate
A nitrated derivative of cellulose. It is made into membrane filters of defined porosity and used for the immobilisation of DNA, RNA or protein. The immobilized molecules is then probed with a labelled nucleic acid sequence or antibody. Nitrocellulose filters are extremely useful in molecular biology for nucleic acid hybridization experiments. They are used extensively in the Southern and Northern blotting procedures for the transfer of DNA and RNA from agarose.
Nitrogen assimilation
The incorporation of nitrogen into organic substances by living organisms.
Nitrogen balance
A state in which the total daily loss of nitrogen equals the daily nitrogen intake.
Nitrogen cycle
The cycling of different forms of nitrogen (in different valence states ) through the microbial, plant and animal worlds and through the atmosphere and geosphere.
Nitrogen fixation
The conversion of atmospheric nitrogen (N2,) into oxidized forms that can be assismilated by plants. Biological nitrogen fixation is catalysed by the enzyme nitrogenase, which is found only in prokaryotes. Certain blue-green algae as well as some genera of bacteria such as Rhizobium spp. And Azotobacter spp. Are capable of fixing nitrogen. Nitrogen-fixing bacteria are very important symbionts for plants that grow in nitrogen –poor soils.
Nitrogen mustard
A Bifunctional alkylating agent that forms DNA adducts as well as DNA- DNA and DNA – protein crosslinks. It is used as a cancer chemotherapeutic agent.
Nitrogenase complex
A system of enzymes that reduces atmospheric nitrogen to ammonia in presence of ATP.
Nitrogenouse bases
Aromatic nitrogen-containing molecules such as purines and pyrimidines that exhibit basic properties. These are constituents of the nucleic acids DNA and RNA.
NK cells
see natural killer cells.
nm
See nanometre
NMDA receptor
N-methyl D-aspartate receptor. A specialised glutamate receptor found on the postsynaptic membrane of neurons that mediate long-term potentiation involved in memory.
NMP
Ribonucleoside monophosphate. See nucleotide.
NMR
Nuclear magnetic resonance. The ability of atoms to switch between spin states in an applied magnetic field. NMR spectra rely on the type of atom, its chemical content and proximity of atoms in space. It is used to analyse protein structures. See X –ray crystallography.
NO
See nucleolar organiser, nitric oxide.
NO bonomics
A novel metabonomics approach for the global profiling of NO metabolism and signaling in vivo. NObonomics has value as a systems-biology platform in drug discovery and information –based medicine.
Nocturia
Increased urination at night.
Nod box
A DNA sequence that regulates that transcription of Rhizobium nodulation genes.
Nod-1
ACED-4/Apaf-1-like molecule that regulates both apoptosis and NF-kB activation pathways. Also known as CARD4.
Nodulation
Formation of nodules on the roots of plants by symbiotic bacteria.
Nodule
The enlargement on roots of nitrogen-fixing plants. The nodules contain symbiotic nitrogen-fixing bacteria. See nitrogen fixation.
NOE
See Nuclear Overhaused Effect.
NOESY
See two-dimensional NOE spectroscopy.
Noise
A small amount of randomly generated variation in sequences added to a model of the sequences such as the Hidden Markov Model to avoid the model overfitting the sequences.
Nonautonomous
A term that refers to biological units that are incapable of functioning by themselves. These units need the assistance of another unit, or “helper”. See autonomous.
Nonautonomous controlling elements.
Defective transposons that can transpose only with the help of an autonomous controlling element of the same type.
Nonclassical cadherins
Adhesive proteins that being to the family of cell adhesion molecules (CAMs). The types of nonclassical cadherins include desmosomal cadherins found in the brain, and nonadhesive proteins such as T-cadherin, which lacks a transmembrane region and is attached by a glycosylphosphatidyl inositol anchor (GPI) to the plasma membrane, and the fat protein, first identified as a tumour suppressor gene product in Drosophila.
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