GLOSSARY OF COMMON BIOTECH TERMS

Allele: alternative form of a gene, e.g. dominant (always expressed if present) or recessive (only expressed if no dominant allele is present).
Amplification: an increase in the number of copies of a specific DNA fragment.
Base pair (bp): two complementary nucleotide bases joined together by chemical bonds. The two strands of the DNA molecule are held together in the shape of a double helix by the bonds between base pairs. The base adenine pairs with thymine, and guanine pairs with cytosine.
Bioinformatics: the science of informatics as applied to biological research. Informatics is the management and analysis of data using advanced computing techniques. Bioinformatics is particularly important as an adjunct to genomics research, because of the large amount of complex data this research generates.
Biomarker: observable change (not necessarily pathological) in the function of an organism, related to a specific exposure or event.
Candidate Gene: A gene that has been implicated in causing or contributing to the development of a particular disease.
C.elegans: Caenorhabditis elegans, a nemotode or roundworm, the first animal to have its genome completely sequenced and all the genes fully characterised.
Chromosome: The DNA in a cell is divided into structures called chromosomes. Chromosomes are large enough to be seen under a microscope. In humans, all cells other than germ cells usually contain 46 chromosomes: 22 pairs of autosomes and either a pair of X chromosomes (in females) or an X chromosome and a Y chromosome (in males). In each pair of chromosomes, one chromosome is inherited from an individual's father and one from his or her mother.
Clone: A term which is applied to genes, cells, or entire organisms which are derived from - and are genetically identical to - a single common ancestor gene, cell, or organism, respectively. Cloning of genes and cells to create many copies in the laboratory is a common procedure essential for biomedical research. Note that several processes which are commonly described as cell 'cloning' give rise to cells which are almost but not completely genetically identical to the ancestor cell. 'Cloning' of organisms from embryonic cells occurs naturally in nature (e.g. with the occurrence of identical twins). The laboratory cloning of a sheep ('Dolly') using the genetic material from a cell of an adult animal has recently been reported.
Cloning: the process of producing a genetically identical copy (clone).
cloning vector: DNA molecule originating from a virus, a plasmid, or the cell of a higher organism into which another DNA fragment of appropriate size can be integrated without loss of the vectors capacity for self-replication; vectors introduce foreign DNA into host cells, where it can be reproduced in large quantities. Examples are plasmids, cosmids, and yeast artificial chromosomes; vectors are often recombinant molecules containing DNA sequences from several sources.
Coding regions: those parts of the DNA that contain the information needed to form proteins. Other parts of the DNA may have non-coding functions (e.g. start-stop, pointing or timer functions) or as yet unresolved functions or maybe even 'noise'.
Codon: a set of three nucleotide bases in a DNA or RNA sequence, which together code for a unique amino acid. For example, the set AUG (adenine, uracil, guanine) codes for the amino acid methionine.
Combinatorial Chemistry: A technique for rapidly and systematically assembling a variety of molecular entities, or building blocks, in many different combinations, to create tens of thousands of diverse compounds that can be tested in drug discovery screening assays to identify potential useful candidates.
Complementary DNA (cDNA): cDNA is DNA that is synthesised in the lab from mRNA by reverse transcription. A cDNA is so-called because its sequence is the complement of the original mRNA sequence.
Deletion: in the process of DNA replication, a deletion occurs if a nucleotide or series of nucleotides is not copied. Such deletions may be harmless, may result in disease, or may in rare cases be beneficial.
Deoxyribose: A type of sugar which is a component of DNA (Deoxyribonucleic Acid). DNA is a molecule formed of two strands, each of which includes deoxyribose.
DNA (Deoxyribonucleic Acid): the molecule that encodes genetic information. DNA is a double-stranded helix held together by bonds between pairs of nucleotides. See base, base pair, and double helix.
DNA probe: a piece of single-stranded DNA, typically labelled so that it can be detected (for example, a radioactive or fluorescent label can be used), which can single out and bind with (and only with) another specific piece of DNA. DNA probes can be used to determine which sequences are present in a given length of DNA or which genes are present in a sample of DNA.
DNA repair genes: genes which code for proteins which correct 'mistakes' in DNA sequences. When these genes are altered, mutations may be able to accumulate in the genome, ultimately resulting in disease. See genetic mutation, p53 and suppressor gene.
DNA replication: the process of making copies of strands of DNA. Existing DNA is used as a template for synthesising the new strands.
Electrophoresis: A method of separating large molecules (such as DNA fragments or proteins) from a mixture of similar molecules. An electric current is passed through a medium containing the mixture, and each kind of molecule travels through the medium at a different rate, depending on its electrical charge and size. Separation is based on these differences. Agarose and acrylamide gels are the media commonly used for electrophoresis of proteins and nucleic acids.
Endonuclease: An enzyme that cleaves its nucleic acid substrate at internal sites in the nucleotide sequence.
Exogenous DNA: DNA which has been introduced into an organism but which originated outside that organism (e.g. material inserted into a cell by a virus).
Exon: exons are those portions of a gene which code for proteins.
Expressed sequence tag (EST): a short strand of DNA (approximately 200 base pairs long) which is part of a cDNA. Because an EST is usually unique to a particular cDNA, and because cDNAs correspond to a particular gene in the genome, ESTs can be used to help identify unknown genes and to map their position in the genome.
Full gene sequence: the complete order of bases in a gene. This order determines which protein a gene will produce.
Gene: a length of DNA which codes for a particular protein, or in certain cases a functional or structural RNA molecule.
Gene _Expression: the process by which the information in a gene is used to create proteins.
Gene Families: Groups of closely related genes that make similar products.
Gene Library: A collection of cloned DNA fragments which, taken together, represent the entire genome of a specific organism. Such libraries or 'gene banks' are assembled so as to allow the isolation and study of individual genes. Gene libraries are produced by first breaking up or 'fractionating' an entire genome. This fractionation can be accomplished either by physical methods or by use of restriction enzymes. The genome fragments are then cloned (multiplied in number) and stored for later use.
Gene Product: the protein produced by a gene.
Genetic Code: the set of codons in DNA or mRNA. Each codon is made up of three nucleotides which call for a unique amino acid. For example, the set AUG (adenine, uracil, guanine) calls for the amino acid methionine. The sequence of codons along an mRNA molecule specifies the sequence of amino acids in a particular protein.
Genetic Engineering: altering the genetic material of cells or organisms in order to make them capable of making new substances or performing new functions.
Genetic Map: a map of a genome which shows the relative positions of the genes and/or markers on the chromosomes.
Genetic Mutation: a change in the nucleotide sequence of a DNA molecule. Genetic mutations are a kind of genetic polymorphism. The term 'mutation', as opposed to 'polymorphism', is generally used to refer to changes in DNA sequence which are not present in most individuals of a species and either have been associated with disease (or risk of disease) or have resulted from damage inflicted by external agents (such as viruses or radiation).
  a difference in DNA sequence among individuals, groups, or populations (e.g. a genetic polymorphism might give rise to blue eyes versus brown eyes, or straight hair versus curly hair). Genetic polymorphisms may be the result of chance processes, or may have been induced by external agents (such as viruses or radiation). If a difference in DNA sequence among individuals has been shown to be associated with disease, it will usually be called a genetic mutation. Changes in DNA sequence which have been confirmed to be caused by external agents are also generally called 'mutations' rather than 'polymorphisms'.
Genetic Predisposition: susceptibility to a disease which is related to a genetic mutation, which may or may not result in actual development of the disease.
Genomic DNA: The basic chromosome set consisting of a species-specific number of linkage groups and the genes contained therein.
Genome: all the genetic material in the chromosomes of a particular organism; its size is generally given as its total number of base pairs.
Genomic Library: A collection of clones made from a set of randomly generated overlapping DNA fragments representing the entire genome of an organism.
Genomics: the study of genes and their function. Recent advances in genomics are bringing about a revolution in our understanding of the molecular mechanisms of disease, including the complex interplay of genetic and environmental factors. Genomics is also stimulating the discovery of breakthrough healthcare products by revealing thousands of new biological targets for the development of drugs, and by giving scientists innovative ways to design new drugs, vaccines and DNA diagnostics. Genomics-based therapeutics include 'traditional' small chemical drugs, protein drugs, and potentially gene therapy.
Genotype: the particular genetic pattern seen in the DNA of an individual. 'Genotype' is usually used to refer to the particular pair of alleles that an individual possesses at a certain location in the genome. Compare this with phenotype.
Hepatocytes: liver cells.
Hepatotoxicity: toxicity to the liver.
Heterologous _Expression Systems: systems that allow _expression of a gene in a different organism.
Human Genome Project: an international research effort aimed at discovering the full sequence of bases in the human genome. Led in the United States by the National Institutes of Health and the Department of Energy.
Human Genome Initiative: Collective name for several projects begun in 1986 by DOE to (1) create an ordered set of DNA segments from known chromosomal locations, (2) develop new computational methods for analyzing genetic map and DNA sequence data, and (3) develop new techniques and instruments for detecting and analyzing DNA. This DOE initiative is now known as the Human Genome Program. The national effort, led by DOE and NIH, is known as the Human Genome Project
Hybridization: The process of joining two complementary strands of DNA or one each of DNA and RNA to form a double-stranded molecule.
Idiosyncrasy: specific (and usually unexplained) reaction of an individual to e.g. a chemical exposure to which most other individuals do not react at all. Examples: some people react to their first aspirin with a potentially fatal shock. General allergic reactions do not fall into this category.
In Situ Hybridization (ISH): Use of a DNA or RNA probe to detect the presence of the complementary DNA sequence in cloned bacterial or cultured eukaryotic cells.
E intron: a length of DNA which is interspersed among the protein-coding sequences (exons) in a gene. Introns are transcribed (see transcription) into mRNA but are then cut out of the mRNA sequence before protein synthesis occurs.
Kilobase (kb): a length of DNA equal to 1000 nucleotides.
Knockout Animals: genetically engineered animals in which one or more genes, usually present and active in the normal animal, are absent or inactive.
Library: a set of clones of DNA sequences from an organism's genome. A particular library might include, for example, clones of all of the DNA sequences expressed in a certain kind of cell, or in a certain organ of the body.
Marker: a sequence of bases at a unique physical location in the genome, which varies sufficiently between individuals that its pattern of inheritance can be tracked through families and/or it can be used to distinguish among cell types. A marker may or may not be part of a gene. Markers are essential for use in linkage studies and genetic maps to help scientists to narrow down the possible location of new genes, and to discover the associations between genetic mutations and disease.
Messenger RNA (mRNA): the DNA of a gene is transcribed (see transcription) into mRNA molecules, which then serve as a template for the synthesis of proteins.
Metabonome: constituent metabolites in a biological sample.
Metabonomics: techniques available to identify the presence and concentrations of metabolites in a biological sample.
Murine: of the mouse.
Mutation: A change, deletion, or rearrangement in the DNA sequence that may lead to the synthesis of an altered inactive protein the loss of the ability to produce the protein. If a mutation occurs in a germ cell, then it is a heritable change in that it can be transmitted from generation to generation. Mutations may also be in somatic cells and are not heritable in the traditional sense of the word, but are transmitted to all daughter cells.
Nephrotoxicity: toxicity to the kidney.
NMR: Nuclear Magnetic Resonance, a technique to identify atoms in a sample by measuring the signal given off by the relaxation of e.g. protons previously aligned in a strong magnetic field.
Non-genotoxic Carcinogen: a substance that causes cancer, not by primarily damaging the genetic material, but by mechanisms that stimulate cell proliferation, thus increasing the chances for natural mutations to be reproduced, and/or selection of specific cell populations that may derange in a later stage.
Nucleic Acid: one of the family of molecules which includes the DNA and RNA molecules. Nucleic acids were so named because they were originally discovered within the nucleus of cells, but they have since been found to exist outside the nucleus as well.

Nucleotide: the 'building block' of nucleic acids, such as the DNA molecule. A nucleotide consists of one of four bases - adenine, guanine, cytosine, or thymine - attached to a phosphate-sugar group. In DNA the sugar group is deoxyribose, while in RNA (a DNA-related molecule which helps to translate genetic information into proteins), the sugar group is ribose, and the base uracil substitutes for thymine. Each group of three nucleotides in a gene is known as a codon. A nucleic acid is a long chain

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