The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Abbreviation for:deoxyribonucleic acid did not arrive did not attend, see thirteen's Medical Dictionary.
Deoxyribonucleic acid Molecular biology A double-stranded linear macromolecule which encodes an organism's genetic informationMcGraw-Hill Concise Dictionary of Modern Medicine. The very long molecule that winds up to form a CHROMOSOME and that contains the complete code for the automatic construction of the body.
The molecule has a double helix skeleton of alternating sugars (deoxyribose) and phosphates. Between the two helices, lying like rungs in a ladder, are a succession of linked pairs of the four bases adenine, thymine, guanine and cytosine.
The sequence of bases along the molecule, taken in groups of three (codons), is the genetic code. Each CODON specifies a particular amino acid to be selected, and the sequence of these, in the polypeptides formed, determines the nature of the protein (usually an ENZYME) synthesized.
Periodicity of DNA is defined as the number of base pairs per turn of the double helix. Collins Dictionary of Medicine © Robert M. Young son 2004, 2005 A complex NUCLEIC ACID molecule found in the chromosomes of almost all organisms, which acts as the primary genetic material, controlling the structure of proteins and hence influencing all enzyme-driven reactions.
The model proposed by WATSON and CRICK in 1953 has now become universally accepted for double-stranded DNA. The two poly nucleotide chains each have an opposite polarity due to the way the phosphates are attached to the sugar groups by 3'- 5' PHOSPHODIESTERASE BONDS.
In this form the molecule is twisted into a right-handed double helix, with a complete turn every tenth base. In E. coli, replication occurs as follows: the DNA unwinds, SSB protein is laid down on the single strands to stabilize them and to prevent rewinding.
An RNA PRIMER initiates DNA synthesis on the leading strand. RNA primers initiate synthesis of each fragment on the lagging strand.
These primers are later removed and the gaps left are filled in by the activity of a DNA polymerase. DNA LIGASE then joins the fragments together to form a complete strand.
In eukaryotes, DNA replication occurs in the ‘S’ phase of the CELL CYCLE prior to nuclear division. In PROKARYOTES, DNA is generally in the form of a single coiled molecule in a continuous loop (see NUCLEOID and may also occur as extra chromosomal material in the cytoplasm.
In EUKARYOTES the DNA is also highly coiled but is complexed with basic and acidic proteins. There are several pieces of evidence to suggest the role of DNA in inheritance: (i) TRANSFORMATION experiments with Streptococcus (Micrococcus) pneumonia in 1928, by F. GRIFFITH ; (ii) the identification of the ‘transforming principle’ as DNA by AVERY MacLeod and McCarty in 1944; (iii) the fact that the wavelength of ultraviolet light which causes most mutations in various prokaryotes and eukaryotes matches the ABSORPTION SPECTRUM of nucleic acids (260 nm); (iv) HERSHEY and Chase's experiment with labelled BACTERIOPHAGE.
DNA has several features which make it an ideal genetic material: great stability (see structure above); accurate replication so that all cells contain an identical copy of information; four nucleotide bases to provide storage of coded information (see GENETIC CODE); it is capable of mutation by altering the base sequence; it may be broken and rejoined to form new genetic combinations (see RECOMBINATION); stored information can be accurately ‘read’ by other cell molecules (see TRANSCRIPTION). The abbreviation for “deoxyribonucleic acid,” the primary carrier of genetic information found in the chromosomes of almost all organisms.
The entwined double structure allows the chromosomes to be copied exactly during cell division. A type of nucleic acid that constitutes the molecular basis of heredity.
It acts as the carrier of genetic information containing the instructions (code) to make proteins. It consists of two single chains of nucleotides, which are twisted round each other to form a double helix or spiral.
The nucleotides contain sugar (deoxyribose), phosphate and the bases (adenine, cytosine, guanine and thymine). The two strands of DNA are held together by hydrogen bonds located between specific pairs of bases (adenine to thymine and cytosine to guanine).
Assessment of DNA has found many applications, including forensic science to help identify a perpetrator (a process called genetic fingerprinting), to establish family relationships or the history of a particular population (phylogenetic). Printer Friendly Also found in: Thesaurus, Medical, Legal, Acronyms, Idioms, Encyclopedia, Wikipedia.
DNA (DEend) n. A nucleic acid that carries the genetic information in cells and some viruses, consisting of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine. The DNA molecule consists of two poly nucleotide chains in the form of a double helix, containing phosphate and the sugar deoxyribose and linked by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine.
Deoxyribonucleic acid: an extremely long, double-stranded nucleic acid molecule arranged as a double helix that is the main constituent of the chromosome and that carries the genes as segments along its strands: found chiefly in the chromatin of cells and in many viruses. The nucleic acid that is the genetic material determining the makeup of all living cells and many viruses.
It consists of two strands of nucleotides linked together in a structure resembling a ladder twisted into a spiral. One of the wonders of nature is that the complexity and diversity of life can be contained in a molecule with a relatively simple structure.
Deoxyribonucleic acid, commonly called DNA, exists mainly in the nucleus and mitochondria of each cell in an organism. It consists of two long strands linked together in a structure resembling a ladder twisted into a spiral, called a double helix.
Specific sequences of these bases, known as genes, form codes that contain all of an organism's genetic information. When other components of a cell “read” this code, they produce proteins, the building blocks of life.
Deoxyribonucleic acid: an extremely long macromolecule that is the main component of chromosomes and is the material that transfers genetic characteristics in all life forms, constructed of two nucleotide strands coiled around each other in a ladderlike arrangement with the sidepieces composed of alternating phosphate and deoxyribose units and the rungs composed of the purine and pyrimidine bases adenine, guanine, cytosine, and thymine: the genetic information of DNA is encoded in the sequence of the bases and is transcribed as the strands unwind and replicate. Compare base pair, gene, genetic code, RNA. The set of nongenetic traits, qualities, or features that characterize a person or thing: Humility is just not in her DNA.
LEARN THE SPANISH WORDS FOR THESE COMMON ANIMALS! Another bishop sailed up the DNA with a fleet of twenty-three ships, and in 1200 founded Riga.
The DNA takes a westerly course towards the Gulf of Riga where it empties near the city of that name. The cup and foot are of agate, probably specimens of the classic period; the mounting, which dates from the time of DNA.
Deoxyribonucleic acid; a nucleic acid that consists of two long chains of nucleotides twisted together into a double helix and joined by hydrogen bonds between complementary bases adenine and thymine or cytosine and guanine; it carries the cell's genetic information and hereditary characteristics via its nucleotides and their sequence and is capable of self-replication and RNA synthesis. The American Heritage® Sherman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company.
The nucleic acid that is the genetic material determining the makeup of all living cells and many viruses. It consists of two long strands of nucleotides linked together in a structure resembling a ladder twisted into a spiral.
In eukaryotic cells, the DNA is contained in the nucleus (where it is bound to proteins known as histones) and in mitochondria and chloroplasts. The workings of the DNA molecule provide the most fundamental explanation of the laws of genetics.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company.