DNA

DEFINITION:

Deoxyribonucleic acid.

nucleic acid

DEFINITION:

A high-molecular-weight nucleotide polymer. There are two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

deoxyribose

DEFINITION:

A deoxypentose found in deoxyribonucleic acids (DNA), deoxyribonucleotides, and deoxyribonucleosides.

constituting

DEFINITION:

Making up or composing.

cellular

DEFINITION:

Pertaining to, or made up of, cells.

organisms

DEFINITION:

Individual living things, whether animals or plants.

nucleus

DEFINITION:

1. The central core of an object or body.

2. A cell nucleus: a spheroid body within a cell, consisting of a number of characteristic organelles visible with the optical microscope, a thin nuclear membrane, a nucleolus or nucleoli, irregular granules of chromatin and linin, and a diffuse nucleoplasm.

3. A group of nerve cells ordinarily located within the central nervous system and bearing a direct relationship to the fibers of a particular nerve.

4. In organic chemistry, the combination of atoms forming the central element or basic framework of the molecule of a specific compound or class of compounds.

nucleus caudatus - Also caudate nucleus . An elongated, arched gray mass closely related to the lateral ventricle throughout its entire extent and consisting of a head, body, and tail. The caudate nucleus and putamen form a functional unit (the neostriatum) of the corpus striatum.

nucleus lentiformis - Also lentiform nucleus . The part of the corpus striatum somewhat resembling a biconvex lens, divided into an external, larger, lateral part, the putamen, and an internal, smaller, lighter colored medial part (globus pallidus), which is in turn subdivided into a smaller, medial, and a larger, lateral part by the medial medullary lamina.

linear

DEFINITION:

Pertaining to or resembling a line.

polymer

DEFINITION:

A compound formed by the joining of smaller molecules, referred to as monomers. The term is generally used to refer either to a macromolecule made up of a large number of monomers linked by covalent bonds, e.g., polypeptides, nucleic acids, polysaccharides, and plastics, or to a protein made up of several subunits linked by covalent or noncovalent bonds, e.g., hemoglobin or lgM immunoglobulin.

backbone

DEFINITION:

1. Columna vertebralis: The bony column in the back of a vertebrate that is the chief support of the trunk and consists of a jointed series of vertebrae enclosing and protecting the spinal cord.

2. Firm resolute character.

linked

DEFINITION:

In genetics, pertaining to linkage (def. 2); See also X-linked under gene .

phosphate

DEFINITION:

1. Any salt of phosphoric acid or its anions, particularly referring to orthophosphate (inorganic phosphate).
2. Any ester of phosphoric acid or of one of its salts or anions; an organic phosphate.

side chains

DEFINITION:

Groups of atoms attached to a larger chain or to a ring; called also "lateral chain."

purine

DEFINITION:

A colorless crystalline heterocyclic compound, C₅H₄N₄, which is not found free in nature, but is variously substituted to produce a group of compounds known as purines or purine bases , of which uric acid is a metabolic end product. The purine bases include adenine and quanine, which are constituents of nucleic acids, and hypoxanthine and xanthine.

adenine

DEFINITION:

A major purine base; in animal and plant cells it usually occurs condensed with ribose or deoxyribose to form the nucleosides adenosine and deoxyadenosine. As such, it is a component of nucleic acids, of certain nucleotides, and of many coenzymes. Symbol A. The official preparation [USP] contains 98 to 102 percent adenine, calculated on the dried basis, and is used to improve the preservation of whole blood.

guanine

DEFINITION:

A purine base, in animal and plant cells usually occurring condensed with ribose or deoxyribose to form the nucleosides guanosine and deoxyguanosine; these nucleosides are components of nucleic acids and of free nucleotides important in metabolism. Symbol G.

pyrimidine

DEFINITION:

An organic compound, a metadiazine, C₄H₄N₂, which is the fundamental form of the pyrimidine bases. These are mostly oxy or amino derivatives. Some of these are constituents of nucleic acid (uracil, thymine, and cytosine).

cytosine

DEFINITION:

A pyrimidine base found in animal and plant cells, usually occurring condensed with ribose or deoxyribose to form the nucleosides cytidine and deoxycytidine, major constituents of nucleic acids. Symbol C.

thymine

DEFINITION:

A pyrimidine base, in animal cells usually occurring condensed with deoxyribose to form the nucleoside deoxythymidine, a component of deoxyribonucleic acid. The corresponding ribonucleoside, thymidine, is a rare constituent of ribonucleic acids.

adenine

DEFINITION:

A major purine base; in animal and plant cells it usually occurs condensed with ribose or deoxyribose to form the nucleosides adenosine and deoxyadenosine. As such, it is a component of nucleic acids, of certain nucleotides, and of many coenzymes. Symbol A. The official preparation [USP] contains 98 to 102 percent adenine, calculated on the dried basis, and is used to improve the preservation of whole blood.

hydrogen

DEFINITION:

The lightest element, an odorless, tasteless, colorless gas that is inflammable and explosive when mixed with air. It is found in water and in almost all organic compounds. Its ion is the active constituent of all acids in the water system. Its symbol is H; atomic number, 1; atomic weight, 1.00797; specific gravity, 0.069. Hydrogen exists in three isotopes: ordinary, or light, hydrogen is the mass 1 isotope, also called protium; heavy hydrogen is the mass 2 isotope, also called deuterium; the mass 3 isotope is tritium.

bonds

DEFINITION:

1. The linkages between two atoms or radicals of a chemical compound.

2. Marks used to indicate the number and attachment of the valences of an atom in constitutional formulas; they are represented by a pair of dots or a line between the atoms.

thymine

DEFINITION:

A pyrimidine base, in animal cells usually occurring condensed with deoxyribose to form the nucleoside deoxythymidine, a component of deoxyribonucleic acid. The corresponding ribonucleoside, thymidine, is a rare constituent of ribonucleic acids.

cytosine

DEFINITION:

A pyrimidine base found in animal and plant cells, usually occurring condensed with ribose or deoxyribose to form the nucleosides cytidine and deoxycytidine, major constituents of nucleic acids. Symbol C.

guanine

DEFINITION:

A purine base, in animal and plant cells usually occurring condensed with ribose or deoxyribose to form the nucleosides guanosine and deoxyguanosine; these nucleosides are components of nucleic acids and of free nucleotides important in metabolism. Symbol G.

double helix

DEFINITION:

See under helix .

antiparallel

DEFINITION:

Denoting molecules that are arranged side by side, but in opposite directions. For example, the strands of deoxyribonucleic acid are antiparallel with their 5' to 3' linkages running in opposite directions.

DNA

DEFINITION:

Deoxyribonucleic acid.

replication

DEFINITION:

1. A turning back of a part so as to form a duplication.

2. Repetition of an experiment to ensure accuracy.

3. The process of duplicating or reproducing, as the replication of an exact copy of a polynucleotide strand of DNA or RNA.

template

DEFINITION:

1. A pattern or mold.
2. In genetics, a strand of DNA or RNA (mRNA) that specifies the base sequence of a newly synthesized strand of DNA or RNA, the two strands being complementary.
3. In dentistry, a curved or flat plate used as an aid in setting teeth in a denture.

synthesis

DEFINITION:

The artificial building up of a chemical compound, by the union of its elements or from other suitable starting materials.

ribonucleic acid

DEFINITION:

RNA; the nucleic acid in which the sugar is ribose, constituting the genetic material in the RNA viruses and playing a role in the flow of genetic information. Ribosyl moieties are linked via phosphate groups attached to their 5' and 3' hydroxyl groups to form the backbone of a linear polymer, with purine and pyrimidine bases attached to the sugars as side chains. The characteristic bases adenine (A), uracil (U), cytosine (C), and guanine (G) are specified by the presence of thymine (T), A, G, and C, respectively, in the gene being transcribed. Many RNA molecules contain bases modified by posttranscriptional processing (methylation, deamination, isomerization), and some contain secondary structure such as base pairing between self-complementary sequences, which stabilizes specific conformations.

transcription

DEFINITION:

The process by which a single-stranded RNA with a base sequence complementary to one strand of a double-stranded DNA is synthesized. The enzymes involved are called DNA-dependent RNA polymerases.