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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Deletion Mutagenesis Deoxyribonucleotide
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Deletion mapping
:A process by which different deletions in a region of DNA are created and used to map the function critical areas of that DNA.
For example, the minimal region of DNA required for a test promoter can be deduced by systematic deletions in the region of interest. This method of physical mapping involves assay of DNA sequence by hybridisation or PCR, or for a gene product.
Deletion mutagenesis
A technique that involves use of restriction enzymes to remove segments of donor DNA from a clone.
Deletion mutation
:A mutation in which one or more nucleotides are removed from a gene.
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Deliberate release Introducing something into the environment. In biotechnology, it refers to the introduction of a genetically modified organism (GMO) from the laboratory into field trials.
Delivery system
An artificial system for the delivery of a drug to s specific target such as in a liposome or tagged to an antibody.
Delta sequences
Short terminal direct found in Ty elements in yeast.
Dementia Pathologic loss of intellectual function.
Demineralisation 1. Bone resorption. This is governed by osteoclasts. 2. To remove the mineral content (salts, ions) from a substance, especially water. The methods of removal include distillation and electrodialysis.
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Demyelination
Loss of myelin sheath, surrounding nerves. This occurs in neurodegenerative diseases such as multiple sclerosis and polio with loss of nerve function.
Denaturation mapping
Partial denaturation of the genome and observation by electron microscopy to identify regional differences in base composition.
Denature
To induce structural changes that disrupt the biological activity of a molecule. Refers to the disruption of hydrogen bonds between base pairs in double-stranded nucleic acid molecules to generate single-stranded polynucleotide, or alterations of the secondary and tertiary structure of a protein that destroy its activity.
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Denaturated DNA
The conversion of double-stranded DNA to single strands by breaking the hydrogen bonds between complementary bases. This is generally achieved by heating.
Denaturing gel
An agarose or acrylamide gel run under conditions in which the secondary and tertiary structures are destroyed. Urea is used to denature DNA, and formaldehyde or glyoxal to destroy higher-order RNA structures. For proteins, 2-mercaptoethanol (to reduce disulfide bonds) and sodium Dodecyl sulfate (SDS) and/or urea are used.
Denaturing gradient gel electrophoresis (DGGE)
The migration of duplex DNA through a gel condition increasing gradient of denaturant until the strands slightly different conditions, generating alleles and heteroduplexes denature under slightly different conditions, generating individual bands.
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Dendrite
A short, branched extension of a nerve cell that receives stimuli from other nerve cells.
Dendritic Cell
A cell that is derived from the bone marrow and present in the lymphoid and other tissues. It functions as an antigen-presenting cell in immune responses and is specialised for the uptake of particulate matter by phagocytosis.
Denaturation
Loss of native conformation of a macromolecule (protein or nucleic acid) by physical or chemical means, without breaking covalent bonds., Denaturation is often accompanied by loss of biological activity. During denaturation, double-stranded DNA separates into single strands. Denaturated proteins unfold their polypeptide chains and show changes in solubility properties.
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Dendrogram
A graphical procedure used to represent the output of a hierarchical clustering method. It is defined as a binary tree with a distinguished root that has all the data items as its leaves. By convention, all the leaves are shown at the same level of the drawing. The ordering of the leaves and their horizontal positions are arbitrary, whereas the heights of the internal nodes may be arbitrary, or related to the metric information used to form the clustering.
Denhart’s solution A solution used for probe hybridisation on filters. The solution contains polyvinylpyrrolidone (PVP), ficoll, bovine serum albumin and nonspecific DNA at high concentration to prevent nonspecific probe hybridisation.
Density gradient
A solution in which there is a range of densities, with the solute being less concentrated at the top and more concentrated in the bottom. The gradient may be stepwise or continous and created by solutions of sucrose or caesium chloride.
Density-gradient centrifugation
A technique for separating molecules according to their density in a gradient varying in solute concentration. Molecules float at a point where their density equals that in a gradient of caesium chloride or sucrose.
Dental Caries
Cavities or holes in the outer two layers of a tooth - the enamel and the dentin caused by bacteria which metabolise carbohydrates to form organic acids which dissolve tooth enamel.
Dental fluorosis
Mottled enamel that occurs in areas where the fluoride concentration in drinking water is 10-45 ppm.
5-deoxyadenosylcobalamin
A metabolically active form of vitamin B12.
Deoxyribonuclease (DNase)
See DNase.
Deoxyribonucleic acid
See DNA.
Deoxyribonucleoside
Any of the nitrogenous bases found in nucleic acids (adenine, guanine, thymine, cytosine) attached to deoxyribose
Deoxyribonucleotide
A Deoxyribonucleoside with phosphate groups attached to the ribose sugar at the 5’ – position. Based on the number of phosphate groups in the 5’ position, deoxyribonucleotides are classified into mono, di and triphosphates. The builiding blocks of DNA are deoxyribonucleoside 5’ triphosphate (dNTPs).
Deoxyribose
A pentose sugar found in DNA that lacks hydroxyl group on the 2’ carbon.
Depolarization
A change in the negative-inside electric potential of a cell at rest that results in a less negative membrane potential.
Depurination
Removal of purines (adenine and guanine) from DNA with the sugar-phosphate backbone remaining intact. This may be enzymatic by chemicals that interact with the bases.
Depression
Removal of a repressor protein from its binding to DNA. The repressor protein when bound to DNA prevents RNA polymerase from initiating transcription. Synonymous with induction.
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