Canadian Medical Guide > Chemicals and Drugs > Nucleic Acids, Nucleotides, and Nucleosides > Nucleic Acids > DNA Terms and Definitions




DNA

Medical Definition: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
Guide Notes: GEN: prefer specifics; /biosyn permitted but consider also DNA REPLICATION; structural DNA models = DNA (IM) + MOLECULAR MODELS (IM)
Also Called: DNA, B-Form,DNA, Double-Stranded
CAS Type 1 Name: CAS Number: 9007-49-2
DNA Categories.
Canadian Medical Guide Definition DNA Adducts - Covalent adducts between chemical mutagens and DNA. Such couplings activate DNA repair processes and, unless repaired prior to DNA replication, may lead to nucleotide substitutions, deletions, and chromosome rearrangements. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)
Canadian Medical Guide Definition DNA Transposable Elements - Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.
Canadian Medical Guide Definition DNA, A-Form - An isoform of DNA that occurs in an environment rich in SODIUM and POTASSIUM ions. It is a right-handed helix with 11 base pairs per turn, a pitch of 0.256 nm per base pair and a helical diameter of 2.3 nm.
Canadian Medical Guide Definition DNA, Archaeal - Deoxyribonucleic acid that makes up the genetic material of archaea.
Canadian Medical Guide Definition DNA, Bacterial - Deoxyribonucleic acid that makes up the genetic material of bacteria.
Canadian Medical Guide Definition DNA, C-Form - An isoform of DNA that occurs under experimental conditions. It is a right-handed helix that is less compact than the B-form of DNA (DNA, B-FORM).
Canadian Medical Guide Definition DNA, Circular - Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)
Canadian Medical Guide Definition DNA, Concatenated - Head to tail array of covalently joined DNA sequences generated by concatenation. It is distinguished from CATENATED DNA in being attached end to end.
Canadian Medical Guide Definition DNA, Cruciform - A cross-shaped DNA structure that can be observed under the electron microscope. It is formed by the incomplete exchange of strands between two double-stranded helices.
Canadian Medical Guide Definition DNA, Fungal - Deoxyribonucleic acid that makes up the genetic material of fungi.
Canadian Medical Guide Definition DNA, Helminth - Deoxyribonucleic acid that makes up the genetic material of helminths.
Canadian Medical Guide Definition DNA, Intergenic - Any of the DNA in between gene-coding DNA, including untranslated regions, 5' and 3' flanking regions, INTRONS, non-functional pseudogenes, and non-functional repetitive sequences. This DNA may or may not encode regulatory functions.
Canadian Medical Guide Definition DNA, Neoplasm - DNA present in neoplastic tissue.
Canadian Medical Guide Definition DNA, Plant - Deoxyribonucleic acid that makes up the genetic material of plants.
Canadian Medical Guide Definition DNA, Protozoan - Deoxyribonucleic acid that makes up the genetic material of protozoa.
Canadian Medical Guide Definition DNA, Recombinant - Biologically active DNA which has been formed by the in vitro joining of segments of DNA from different sources. It includes the recombination joint or edge of a heteroduplex region where two recombining DNA molecules are connected.
Canadian Medical Guide Definition DNA, Ribosomal - DNA sequences encoding ribosomal RNA (RNA, RIBOSOMAL) and the segments of DNA separating the individual ribosomal RNA genes, referred to as ribosomal spacer DNA (DNA, RIBOSOMAL SPACER).
Canadian Medical Guide Definition DNA, Satellite - Highly repetitive DNA sequences found in HETEROCHROMATIN, mainly near centromeres. They are composed of simple sequences (very short) (see MINISATELLITE REPEATS) repeated in tandem many times to form large blocks of sequence. Additionally, following the accumulation of mutations, these blocks of repeats have been repeated in tandem themselves. The degree of repetition is on the order of 1000 to 10 million at each locus. Loci are few, usually one or two per chromosome. They were called satellites since in density gradients, they often sediment as distinct, satellite bands separate from the bulk of genomic DNA owing to a distinct BASE COMPOSITION.
Canadian Medical Guide Definition DNA, Single-Stranded - A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle.
Canadian Medical Guide Definition DNA, Viral - Deoxyribonucleic acid that makes up the genetic material of viruses.
Canadian Medical Guide Definition DNA, Z-Form - A left-handed double helix of DNA. Its name derives from its narrow zigzag structure that is the least twisted and thinnest form of DNA. Z-DNA forming regions within the GENOME may play an important role in GENE EXPRESSION REGULATION.
Canadian Medical Guide Definition Isochores - Large regions of the GENOME that contain local similarities in BASE COMPOSITION.
Canadian Medical Guide Definition Retroelements - Elements that are transcribed into RNA, reverse-transcribed into DNA and then inserted into a new site in the genome. Long terminal repeats (LTRs) similar to those from retroviruses are contained in retrotransposons and retrovirus-like elements. Retroposons, such as LONG INTERSPERSED NUCLEOTIDE ELEMENTS and SHORT INTERSPERSED NUCLEOTIDE ELEMENTS do not contain LTRs.

DNA Medical Definitions and Terms

CANADIAN MEDICAL GUIDE

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