Glossary
Terms starting with N
150 definitions · page 3 of 3.
- NUCLEAR ENERGY
- Power obtained by splitting heavy atoms (fission) or joining light atoms (fusion). A nuclear energy plant uses a controlled atomic chain reaction to produce heat. The heat is used to make steam run conventional turbine generators.
- nuclear fusion
- the process by which two atomic nuclei combine to form a heavier atomic nucleus; this is the energy source that causes most stars to shine
- NUCLEAR INSURANCE
- Covers operators of nuclear reactors and other facilities for liability and property damage in the case of a nuclear accident and involves both private insurers and the federal government.
- NUCLEAR REGULATORY COMMISSION (NRC)
- An independent federal agency that ensures that strict standards of public health and safety, environmental quality and national security are adhered to by individuals and organizations possessing and using radioactive materials. The NRC is the agency that…
- nuclear transplantation
- The technique of placing a nucleus from another source into an enucleated cell.
- nuclease
- One of the several classes of enzymes that degrade nucleic acid. An enzyme that can degrade DNA or RNA by breaking phosphodiester bonds. See endonucleases; exonucleases.
- nuclease hypersensitive site
- Region of eukaryotic chromosome DNA that is specifically vulnerable to nuclease attack perhaps because it is not wrapped in histone as nucleosomes.
- nucleoid
- A DNA mass within a chloroplast or mitochondrion.
- nucleolar organizer
- The chromosomal region around which the nucleolus forms, a site of tandem repeats of the rRNA gene. A region (or regions) of the chromosome set physically associated with the nucleolus and containing rRNA genes.
- nucleolus
- The globular nuclear organelle formed at the nucleolar organizer. Site of ribosome construction. An organelle found in the nucleus, containing rRNA and multiple copies of the genes coding for rRNA.
- nucleoprotein
- The substance of eukaryotic chromosomes consisting of proteins and nucleic acids.
- nucleoside
- A sugar-base compound that is a nucleotide precursor. Nucleotides are nucleoside phosphates. A nitrogen base linked to a sugar molecule.
- nucleosome
- A nu body; the basic unit of eukaryotic chromosome structure; a ball of eight histone molecules wrapped about by two coils of about 220 base pairs of DNA. Arrangement of DNA and histones forming regular spherical structures in eukaryotic chromatin.
- nucleosynthesis
- the creation of heavy elements from lighter ones by nuclear fusion
- nucleotide
- Subunit that polymerizes into nucleic acids (DNA or RNA). Each nucleotide consists of a nitrogenous base; a sugar; and one to three phosphate groups.
- nucleotide pair
- A pair of complementary nucleotides (one in each strand of DNA) that are joined by hydrogen bonds.
- nucleotide-pair substitution
- The replacement of a specific nucleotide pair by a different pair; often mutagenic.
- Nucleus
- A subatomic object with a definite mass and charge.
- nucleus
- the central region of an atom, comet, or galaxy
- nucleus
- The membrane bound organelle containing the genome of eukaryotes organized into chromosomes.
- NUG
- A non-utility generator. A generation facility owned and operated by an entity who is not defined as a utility in that jurisdictional area.
- null allele
- An allele whose effect is either an absence of normal gene product at the molecular level or an absence of normal function at the phenotypic level.
- null hypothesis
- The statistical hypothesis that states that there are no differences between observed and expected data.
- nullisomic
- A diploid cell or individual missing both copies of the same chromosome. A cell or individual with one chromosomal type missing, with a chromosome number such as n-1 or 2n-2.
- Numbers Game
- This term can be used for any lottery game where winners are determined by a random draw of numbers. However, it is often used more specifically for a game where a player selects three or four digits (0 to 9) and matches them with a similar set drawn at…
- numerator element
- Genes on the X chromosome in Drosophila that regulate the sex switch (sxl) to the on condition (femaleness). Refers to the numerator of the X/A (number of X chromosomes/autosomes) genic balance equation.
- nurse cell
- A sister cell of an oocyte in insects. Nurse cells produce the bulk of the cytoplasmic contents of the mature oocyte.
- NURSING HOME INSURANCE
- A form of long-term care policy that covers a policyholder’s stay in a nursing facility.
- Nutmeg
- Nutmeg is a spice from the nutmeg tree, which is native to several Indonesian islands. Both nutmeg and mace come from the same plant. Nutmeg is the 'nut', while mace is the surrounding lacy 'aril'. Nutmeg has a warm, spicy aroma and flavour and can be used…
- NVC
- See National Visa Center