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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Antisense DNA APC Syndrome
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Antimicrobial agent Any chemical or biological agent that prevents the growth of microorganisms.
Antimorphic allele A mutant allele that has an antagonistic reaction to the normal, wild type allele.
Antimutator A gene that decreases the spontaneous mutation rate of an organism. Antimutator ganes are usually involved in DNA repair processes.
Antimycin An inhibitor of electron transport from cytochrome b to cytochrome c. It inhibits both electron transport and ATP synthesis (oxidative phosphorylation).
Antinutrients Substances that inhibit normal uptake of nutrients.
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Antiparallel orientation The normal arrangement of the two strands of nucleic acid duplexes (NDA-DNA, DNA-RNA, RNA-RNA), in which the two strands are riented in opposite directions; ie. the 5-phosphate end of one strand is aligned with the 3-hydroxyl end of the complementary strand.
Antiparallel β-pleated sheet (b-sheet) A secondary structure formed by hydrogen bonding between two or more extended polypeptide chains.
Structure of β-Pleated Sheet 
Antiparasite A substance that inhibits or kills parasites.
Antiport Transport of two substances simultaneously through the cell membrane in opposite directions.
Antiresorptive agents Drugs or hormones that inhibit bone resorption.
Antisense A DNA or RNA strand that is complementary to the target DNA/RNA. Antisense also describes a therapeutic strategy that uses an antisense DNA or RNA sequence to target a specific gene, DNA or mRNA and binds to it thereby inhibiting gene expression.
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Antisense DNA 1. The sequence of chromosomal DNA that is transcribed to RNA.
2. A DNA sequence that has complete or partial complementarity to a functional mRNA.
Antisense gene A gene that produces a transcript (mRNA) that is complementary to the pre-mRNA or mRNA of a normal gene. It is constructed by inverting the coding region relative to the promoter.
Antisense RNA An RNA molecule that has a sequence complementary to a specific mRNA with which it can hybridize and block its function.
Antisense therapy The treatment for a genetic disease based on complementary base pairing between a DNA(RNA) sequence and a specific mRNA. The formation of a DNA(RNA)-RNA hybrid prevents translation.
Antiseptic Any substance that kills or inhibits the growth of disease-causing microorganisms. It is however nontoxic to the cells of the body.
Antiserum The fluid portion of the blood of an animal that contains antibodies.
Anti-terminator A protein that enables RNA polymerase to ignore transcriptional termination signals and read through them to generate longer mRNA transcripts.
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Antithrombin III A circulating plasma protein and an inhibitor of the clotting factors IXa, Xa, XIa and thrombin.
Antitoxin An antibody produced by certain bacteria, plants and animals that has the ability to neutralize a specific toxin.
Anuria Absence of urine formation by the kidney.
AP endonucleases Enzymes that cut DNA on the 5 side of either apurinic or apyrimidinic sites.
AP site Apurinic or apyrimidinic site. An abasic site. A site where the base has been removed from the DNA backbone.
Apaf-1 Apoptosis protease activating factor-1. A human protein homologous to CED 4 in C. elegans that participates with caspase-9 in the cytochrome c-dependent activation of caspase-3, resulting in apoptosis.
APC See adenomatous polyposis coli, anaphase promoting complex.
APC syndrome A genetic disease characterised by the development of benign polyps in the colon, a preneoplastic lesion that progresses to colon cancer. The APC gene is located on the human chromosome 5.
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APH Aminoglycoside 3-phosphotransferase. A bacterial gene encoding an enzyme that confers resistance to the antibiotic neomycin. The APH gene is used as a selectable marker in transfection experiments. Cells that lack the gene are eliminated on exposure to neomycin.
Apical Refers to the tip of a cell, a structure or an organ. The apical surface of an epithelial cell is the exposed free surface.
Apo A The major apolipoprotein found in LDL, VLDL and chylomicrons. Apo B-48 of chylomicrons is synthesised in the intestine. Apo B-100 found in LDL and VlDL is synthesised in the liver and is a very large single polypeptide of 4536 amino acid residues.
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Apo C Small apolipoproteins that comprise apo C-I, C-ii and C-iii. They freely exchange between different lipoproteins.
Apo D A subfraction of HDL.
Apo E An arginine-rich apolipoprotein found in VLDL and HDL.
Antioncogene A gene whose product prevents the development of cancer. See tumour suppressor gene.
Antioxidant A substance which when present at low concentrations compared to those of an oxidisable substrate, significantly delays or prevents oxidation of that substrate. Antioxidants act by interrupting an oxidative sequence by removal of oxygen or metal catalysts, inactivating intermediates, scavenging initiating radicals or breaking initiated chain reactions. Some examples of antioxidants include vitamin C, vitamin E, b-carotene, glutathione etc.
Apoactivator A regulatory protein that stimulates transcription in the presence of a coactivator.
Apoenzyme The protein part of an enzyme.
Apoinducer A protein that binds to DNA and turns on transcription by RNA polymerase.
Apolipoprotein Protein part of a lipoprotein.
Apoprotein The protein part of a protein, excluding the organic or inorganic prosthetic groups or cofactors.
Apoptosis Programmed cell death. A genetically controlled process essential for normal development, morphogenesis, tissue remodeling and homeostasis. It is characterised by DNA fragmentation, cytoplasmic shrinkage, nuclear condensation, membrane blebbing and cell death without lysis or damage to neighbouring cells. Cells that have undergone apoptosis are removed by Phagocytosis by macrophages or neighbouring cells. Two major pathways are involved in apoptotic cell death-the extrinsic or the death receptor pathway and the intrinsic or the mitochondrial pathway. Both the pathways converge at the activation of caspases that eventually carries out a proteolytic death execution programme. The Bcl-2 family of proteins play a major role in the regulation of both the intrinsic and extrinsic pathways. In addition to caspases-dependent pathway, apoptosis can also be executed by a caspases independent apoptosis inducing factor (AIF) pathway. Defects in apoptotic regulation are seen in pathological conditions such as cancer and AIDS. Apoptosis differs from necrosis, in which cell death is caused by a toxic substance.
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