Annex 1 Glossary of Terms Commonly Used in Biotechnology
Glossary of the most commonly used terms that appear in reports about biotechnology and genetic engineering. The explanations are kept as simple as possible.
Acclimatisation
Adaptation of an organism to a new environment.
Active immunity
A type of acquired immunity whereby resistance to a disease is built up by either having the disease or receiving a vaccine against it.
Active site
The part of a protein that must be maintained in a specific shape if the protein is to be functional, for example, the part to which the substrate binds in an enzyme. The part of an enzyme where the actual enzymatic function is performed.
Adaptation
In the evolutionary sense, some heritable feature of an individual’s phenotype that improves its chances of survival and reproduction in the existing environment.
Additive genetic variance
Genetic variance associated with the average effects of substituting one allele for another.
Adjuvant
Insoluble material that increases the formation and persistence of antibodies when injected with an immunogen.
Aerobic
Needing oxygen for growth.
Affinity chromatography
A technique used in bioprocess engineering and analytical biochemistry for separation and purification of almost any biomolecule, but typically a protein, on the basis of its biological function or chemical structure. The molecule to be purified is specifically and reversibly adsorbed by a complementary binding substance (ligand) that is immobilised on a matrix, the matrix usually being in the form of beads. The matrix then is washed to remove contaminants, and the molecule of interest is dissociated from the ligand and is recovered from the matrix in purified form by changing the experimental conditions.
Agglutinin
An antibody that, is capable of recognising and binding to an immunological determinant on the surface of bacteria or other cells and causing them to clump (agglutination).
Agrobacterium
A bacterium normally responsible for production of crown gall disease in a variety of plants. A plasmid has been isolated from this bacterium that is useful in plant genetic engineering. This plasmid, called the Ti plasmid, has been modified so that it does not cause disease but can carry foreign DNA into susceptible plant cells.
Allelle
Any of several alternative forms of a given gene.
Allele frequency
Often called gene frequency. A measure of how common an allele is in a population; the proportion of all alleles at one gene locus that are of one specific type in a population.
Allelic exclusion
A process whereby only one immunoglobulin light chain and one heavy chain gene are transcribed in any one cell; the other genes are repressed.
Allogenic
Of the same species, but with a different genotype.
Allopolyploid
Polyploid produced by the hybridisation of two species.
Allotype
The protein product (or the result of its activity) of an allele which may be detected as an antigen in another member of the same species.(e.g. histocompatibility antigens, immunoglobulins), obeying the rules of simple Mendelian inheritance.
Alternative splicing
Various ways of splicing out introns in eukaryotic pre-mRNAs resulting in one gene producing several different mRNAs and protein products.
Alu family
A dispersed intermediately repetitive DNA sequence found in the human genome in about three hundred thousand copies. The sequence is about 300 bp long. The name Alu comes from the restriction endonuclease AluI that cleaves it.
Ames test
A widely used test to detect possible chemical carcinogens; based on mutagenicity in the bacterium Salmonella.
Amino acids
Building blocks of proteins. There are twenty common amino acids: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine.
Amplification
The process of increasing the number of copies of a particular gene or chromosomal sequence. This can also include amplification of the signal to improve detection as an alternative to amplification of the sequence.
Anaerobic
Growing in the absence of oxygen.
Aneuploidy
The condition of a cell or of an organism that has additions or deletions of a small number of whole chromosomes from the expected balanced diploid number of chromosomes.
Annealing
Spontaneous alignment of two complementary single polynucleotide (RNA, or DNA, or RNA and DNA) strands to form a double helix.
Anti-oncogene
A gene that prevents malignant (cancerous) growth and whose absence, by mutation, results in malignancy (e.g. retinoblastoma).
Antibiotic
Chemical substance formed as a metabolic byproduct in bacteria or fungi and used to treat bacterial infections. Antibiotics can be produced naturally, using microorganisms, or synthetically.
Antibody
Protein produced by humans and higher animals in response to the presence of a specific antigen.
Anticodon
Triplet of nucleotide cases (codon) in transfer RNA that pairs with (is complementary to) a triplet in messenger RNA. For example, if the codon is UCG, the anticodon might be AGC.
Antigen
A substance to which an antibody will bind specifically.
Antigenic determinant
See Hapten.
Antihemophilic factors
A family of whole-blood proteins that initiate blood clotting, such as Factor VIII and kidney plasminogen activator.
Antisense RNA
RNA produced by copying and reversing a portion of an RNA-encoding DNA, usually including a protein-specifying region, and placing it next to a transcription-control sequence. This cassette can be delivered to the target cell, resulting in genetic transformation and production of RNA that is complementary to the RNA that is produced from the original, not-reversed, DNA segment. This complementary, or antisense, RNA is able to bind to the complementary sequences of the target RNA, resulting in inhibition of expression of the target gene.
Antiserum
Blood serum containing specific antibodies against an antigen. Antisera are used to confer passive immunity to many diseases and as analytical and preparative reagents for antigens.
Assay
Technique for measuring a biological response.
Attenuated
Weakened; with reference to vaccines, made from pathogenic organisms that have been treated so as to render them avirulent.
Autoimmune disease
A disease in which the body produces antibodies against its own tissues.
Autoimmunity
A condition in which the body mounts an immune response against one of its own organs or tissues.
Autosome
Any chromosome other than a sex chromosome.
Avirulent
Unable to cause disease.
Bacillus subtilis
A bacterium commonly used as a host in recombinant DNA experiments. Important because of its ability to secrete proteins.
Bactericide
An agent that kills bacteria. Also called biocide or germicide.
Bacteriophage
Virus that reproduces in and kills bacteria. Also called phage.
Bacterium
Any of a large group of microscopic, single-cell organisms with a very simple cell structure. Some manufacture their own food from inorganic precursors alone, some live as parasites on other organisms, and some live on decaying matter.
Base
On the DNA molecule, one of the four chemical units that, according to their order, represent the different amino acids. The four bases are: adenine (A), cytosine(C), guanine (G), and thymine(T). In RNA, uracil (U) substitutes for thymine.
Base pair
Two nucleotide bases on different strands of a nucleic acid molecule that bond together. The bases generally pair in only two combinations; adenine with thymine (DNA) or uracil (RNA), and guanine with cytosine.
Batch processing
Growth in a closed system with a specific amount of nutrient medium. In bioprocessing, defined amounts of nutrient material and living matter are placed in a bioreactor and removed when the process is completed. Cf. Continuous processing.
Bioassay
Determination of the effectiveness of a compound by measuring its effect on animals, tissues, or organisms, usually in comparison with a standard preparation.
Biocatalyst
In bioprocessing, an enzyme that activates or speeds up a biochemical reaction.
Biochemical
The product of a chemical reaction in a living organism.
Biochip
Electronic device that uses biologically derived or related organic molecules to form a semiconductor.
Biocide
An agent capable of killing almost any type of cell.
Bioconversion
Chemical restructuring of raw materials by using a biocatalyst.
Biodegradable
Capable of being broken down by the action of microorganisms under conditions generally found in the environment.
Biological oxygen demand (BOD)
The amount of oxygen used for growth by organisms in water that contains organic matter, in the process of degrading that matter.
Biologic response modulator
A substance that alters the growth or functioning of a cell. Includes hormones and compounds that affect the nervous and immune systems.
Biomass
The totality of biological matter in a given area. As commonly used in biotechnology, refers to the use of cellulose, a renewable resource, for the production of chemicals that can be used to generate energy or as alternative feedstocks for the chemical industry to reduce dependence on non-renewable fossil fuels.
Bioprocess
A process in which living cells, or components thereof, are used to produce a desired end product.
Bioreactor
Vessel used for bioprocessing.
Biosynthesis
Production of a chemical by a living organism.
Biotechnology
Biotechnology may be defined as the use of living organisms or their sub-cellular components to develop useful products, processes or services.
B lymphocytes (B-cells)
A class of lymphocytes, released from the bone marrow and which produce antibodies.
Bovine somatotropin (also called bovine growth hormone)
A hormone secreted by the bovine pituitary gland. It has been used to increase milk production by improving the feed efficiency in dairy cattle.
Callus
A cluster of undifferentiated plant cells that can, for some species, be induced to form the whole plant.
Carcinogen
Cancer-causing agent.
Catalyst
An agent (such as an enzyme or a metallic complex) that facilitates a reaction but is not itself changed at completion of the reaction.
Cell
The smallest structural unit of living organisms that is able to grow and reproduce independently.
Cell culture
Growth of a collection of cells, usually of just one genotype, under laboratory conditions.
Cell fusion
See Fusion.
Cell line
Cells which grow and replicate continuously in cell culture outside the living organism.
Cell-mediated immunity
Acquired immunity in which T lymphocytes play a predominant role. Development of the thymus in early life is critical to the proper development and functioning of cell-mediated immunity.
Chemostat
Growth chamber that keeps a bacterial or other cell culture at a specific volume and rate of growth by continually adding fresh nutrient medium while removing spent culture.
Chimera
An individual (animal, plant, or lower multicellular organism) composed of cells of more than one genotype. Chimeras are produced, for example, by grafting an embryonic part of one species onto an embryo of either the same or a different species.
Chromosomes
Threadlike components in the cell that contain DNA and proteins. Genes are carried on the chromosomes.
Cistron
A length of chromosomal DNA representing the smallest functional unit of heredity, essentially identical to a gene.
Clone
A group of genes, cells, or organisms derived from a common ancestor. Because there is no combining of genetic material (as in sexual reproduction), the members of the clone are genetically identical or nearly identical to the parent.
Codon
A sequence of three nucleotide bases that in the process of protein synthesis specifies an amino acid or provides a signal to stop or start protein synthesis (translation).
Coenzyme
An organic compound that is necessary for the functioning of an enzyme. Coenzymes are smaller than the enzymes themselves and may be tightly or loosely attached to the enzyme protein molecule.
Cofactor
A nonprotein substance required for certain enzymes to function. Cofactors can be coenzymes or metallic ions.
Colony-stimulating factors
A group of lymphokines which induce the maturation and proliferation of white blood cells from the primitive cell types present in bone marrow.
Complementarity
The relationship of the nucleotide bases on two different strands of DNA or RNA. When the bases are paired properly (adenine with thymine [DNA] or uracil [RNA] and guanine with cytosine), the strands are said to be “complementary.”
Complementary DNA (cDNA)
DNA synthesised from an RNA template rather than from a DNA template. This type of DNA is used for cloning or as a DNA probe for locating specific genes in DNA hybridisation studies.
Conjugation
Sexual reproduction of bacterial cells in which there is a one-way exchange of genetic material between the cells in contact.
Continuous processing
A method of bioprocessing in which new materials are added and products removed continuously at a rate that maintains the volume at a specific level and usually maintain the composition of the mixture as well. Cf. Batch processing and chemostat.
Crossing over
Exchange of genes between two paired chromosomes.
Culture
As a noun, cultivation of living organism in prepared medium; as a verb, to grow in prepared medium.
Culture medium
Any nutrient system for the artificial cultivation of bacteria or other cells; usually a complex mixture of organic and inorganic materials.
Cyto
A prefix referring to cell or cell plasm.
Cytogenetics
Study of the cell and its heredity-related components, especially the study of chromosomes as they occur in their “condensed” state, when not replicating.
Cytokines
Intercellular signals, usually protein or glycoprotein, involved in the regulation of cellular proliferation and function.
Cytoplasm
Cellular material that is within the cell membrane and surround the nucleus.
Cytotoxic
Able to cause cell death. A cytotoxic substance is usually more subtle in its action than is a biocide.
Defensin
A natural defense protein isolated from cattle. It may prove effective against shipping fever, a viral disease that attacks cattle during transport, causing an estimated 250 million US dollars in losses each year.
Deoxyribonucleic acid (DNA)
The molecule that carries the genetic information for most living systems. The DNA molecule consists of four bases (adenine, cytosine, guanine, and thymine) and a sugar-phosphate backbone, arranged in two connected strands to form a double helix. See also Complementary DNA; Double helix; Recombinant DNA; Base pair.
Diagnostic
A product used for the diagnosis of disease or medical condition. Both monoclonal antibodies and DNA probes are useful diagnostic products.
Differentiation
The process of biochemical and structural changes by which cells become specialised in form and function as the organism develops.
Diploid
A cell with two complete sets of chromosomes. Cf. Haploid.
DNA
See Deoxyribonucleic acid.
DNA probe
A molecule (usually a nucleic acid) that has been labelled with a radioactive isotope, dye, or enzyme and is used to locate a particular nucleotide sequence or gene on a DNA or RNA molecule.
Double helix
A term often used to describe the configuration of the DNA molecule. The helix consists of two spiraling strands of nucleotides (a sugar, phosphate, and base), joined crosswise by specific pairing of the bases. See also Deoxyribonucleic acid; Base; Base pair.
Downstream processing
The stages of processing that take place after the fermentation or bioconversion stage, includes separation, purification, and packaging of the product.
Drug Delivery
The process by which a formulated drug is administered to the patient. Traditional routes have been orally or by intravenous perfusion. New methods that are being developed are through the skin by application of a transdermal patch or across the nasal membrane by administration of a specially formulated aerosol spray.
Electrophoresis
A technique for separating different types of molecules in a gel (or liquid), ion-conducting medium, based on their differential movement in an applied electrical field.
Endonuclease
An enzyme that breaks nucleic acids at specific interior bonding sites; thus producing nucleic acid fragments of various lengths. Cf. Exonuclease.
Enzyme
A protein catalyst that facilitates specific chemical or metabolic reactions necessary for cell growth and reproduction. Cf. Catalyst.
Epitope
A site on the surface of a macromolecule capable of being recognised by an antibody. An epitope may consist of just a few amino-acid residues in a protein or a few sugar residues in a polysaccharide. A synonym is “immunological determinant.”
Erythropoietin (EPO)
A protein that boosts production of red blood cells. It is clinically useful in treating certain types of anemias.
Escherichia coli (E. coli)
A bacterium that inhabits the intestinal tract of most vertebrates. Much of the work using recombinant DNA techniques has been carried out with this organism because it has been genetically very well characterised.
Eukaryote
A cell or organism containing a true nucleus, with a well-defined membrane surrounding the nucleus. All organisms except bacteria, archebacteria, viruses, and blue-green algae are eukaryotic. Cf. Prokaryote.
Exon
In eukaryotic cells, the part of the gene that is transcribed into messenger RNA and encodes a protein. See also Intron; Splicing.
Exonuclease
An enzyme that breaks down nucleic acids only at the ends of polynucleotide chains, thus releasing one nucleotide at a time, in sequential order. Cf. Endonuclease.
Expression
In genetics, manifestation of a characteristic that is specified by a gene. With hereditary diseases, for example, a person can carry the gene for the disease but not actually have the disease. In this case, the gene is present but not expressed. In molecular biology and industrial biotechnology, the term is often used to mean the production of a protein by a gene that has been inserted into a new host organism.
Expressed sequence tags (ESTs)
A unique DNA sequence derived from a cDNA library (therefore from a sequence which has been transcribed in some tissue or at some stage of development). The EST can be mapped, by a combination of genetic mapping procedures, to a unique locus in the genome and serves to identify that gene locus.
Factor VIII
A large, complex protein that aids in blood clotting and is used to treat hemophilia. See also Antihemophilic factors.
Feedstock
The raw material used in chemical or biological processes.
Fermentation
An anaerobic process of growing microorganisms for the production of various chemical or pharmaceutical compounds. Microbes are normally incubated under specific conditions in the presence of nutrients in large tanks called fermentors.
Frameshift
Insertion or deletion of one or more nucleotide bases such that incorrect triplets of bases are read as codons.
Fusion
Joining of the membrane of two cells, thus creating a new, fused cell that contains at least some of the nuclear material from both parent cells. Used in making hybridomas.
Fusion protein
A protein with a polypeptide chain derived from two or more proteins. A fusion protein is expressed from a gene prepared by recombinant DNA methods from the portions of genes encoding two or more proteins.
Gene
A segment of chromosome that encodes the necessary regulatory and sequence information to direct the synthesis of a protein or RNA product. See also Operator; Regulatory g.; Structural g.; Suppressor g.
“Gene machine”
A computer controlled, solid-state chemistry device for synthesising oligodeoxyribonucleotides by combining chemically-activated precursors of deoxyribonucleotides (bases) sequentially in the proper order.
Gene mapping
Determination of the relative locations of genes on a chromosome.
Gene sequencing
Determination of the sequence of nucleotide bases in a strand of DNA.
Gene therapy
The replacement of a defective gene in an organism suffering from a genetic disease. Recombinant DNA techniques are used to isolate the functioning gene and insert it into cells. Over three hundred single gene genetic disorders have been identified in humans. A significant percentage of these may be amenable to gene therapy.
Genetic code
The mechanism by which genetic information is stored in living organisms. The code uses sets of three nucleotide bases (codons) to make the amino aids that, in turn, constitute proteins.
Genetic engineering
A technology used to alter the genetic material of living cells in order to make them capable of producing new substances or performing new functions.
Genetic map
A linear designation of sites within a chromosome or genome, based upon the various frequencies of recombination between genetic markers. See linkage map.
Genetic screening
The use of a specific biological test to screen for inherited diseases or medical conditions. Testing can be conducted prenatally to check for metabolic defects and congenital disorders in the developing foetus as well as post-natally to screen for carriers of heritage diseases.
Genome
The total hereditary material of a cell, comprising the entire chromosomal set found in each nucleus of a given species.
Genotype
Genetic make-up of an individual or group. Cf. Phenotype.
Germ cell
Reproductive cell (sperm or egg). Also called gamete or sex cell.
Germicide
See Bactericide.
Germplasm
The total genetic variability, represented by germ cells or seeds, available within a particular population of organisms.
Gene pool
The total genetic information contained within a given population.
Growth hormone (also called somatotropin)
A protein produced by the pituitary gland that is involved
in cell growth.
Human growth hormone is clinically used to treat dwarfism. Various animal
growth hormones can be used to improved milk production as well as producing
a leaner variety of meat.
Haploid
A cell with half the usual number of chromosomes, or only one chromosome set. Sex cells are haploid. Cf. Diploid.
Hapten
A small molecule which, when chemically coupled to a protein, acts as an immunogen and stimulates the formation of antibodies not only against the two-molecule complex but also against the hapten alone.
Hemagglutination
Clumping (agglutination) of red blood cells, for example by antibody molecules or virus particles.
Hereditary
Capable of being transferred as genetic information from parent cells to progeny.
Histocompatibility
Immunologic similarity of tissues such that grafting can be done without tissue rejection.
Histocompatibility antigen
An antigen that causes the rejection of grafted material from an animal different in genotype from that of the host animal.
Homologous
Corresponding or alike in structure, position, or origin.
Hormone
A chemical that acts as a messenger or stimulatory signal, relaying instructions to stop or start certain physiological activities. Hormones are synthesised in one type of cell and then released to direct the function of other cell types.
Host
A cell or organism used for growth of a virus, plasmid, or other form of foreign DNA, or for the production of cloned substances.
Host-vector system
Combination of DNA-receiving cells (host) and DNA-transporting substance (vector) used for introducing foreign DNA into a cell.
Humoral immunity
Immunity resulting from circulating antibodies in plasma protein.
Hybridisation
Production of offspring, or hybrids, from genetically dissimilar parents. The process can be used to produce hybrid plants (by cross-breeding two different varieties) or hybridomas (hybrid cells formed by fusing two unlike cells, used in producing monoclonal antibodies). The term is also used to refer to the binding of complementary strands of DNA or RNA.
Hybridoma
The cell produced by fusing two cells of different origin. In monoclonal antibody technology, hybridomas are formed by fusing an immortal cell (one that divides continuously) and an antibody-producing cell. See also Monoclonal antibody; Myeloma.
Immune serum
Blood serum containing antibodies.
Immune system
The aggregation of cells, biological substances (such as antibodies), and cellular activities that work together to provide resistance to disease.
Immunity
Nonsusceptibility to a disease or to the toxic effects of antigenic material. See also Active i., Cell-mediated i.; Humoral i.; Natural active i.; Natural passive.; Passive i.
Immunoassay
Technique for identifying substances based on the use of antibodies.
Immunodiagnostics
The use of specific antibodies to measure a substance. This tool is useful in diagnosing infectious diseases and the presence of foreign substances in a variety of human and animal fluids (blood, urine, etc.) It is currently being investigated as a way of locating tumor cells in the body.
Immunofluorescence
Technique for identifying antigenic material that uses antibody labelled with fluorescent material. Specific binding of the antibody and antigen can be seen under a microscope by applying ultraviolet light rays and noting the visible light that is produced.
Immunogen
Any substance that can elicit an immune response, especially specific antibody production. An immunogen that reacts with the elicited antibody may be called an antigen.
Immunoglobulin
General name for proteins that function as antibodies. These proteins differ somewhat in structure, and are grouped into five categories on the basis of these differences: immunoglobulin G (IgG) IgM, IgA, IgD and IgE.
Immunology
Study of all phenomena related the body’s response to antigenic challenge (i.e. immunity, sensitivity, and allergy).
Immunomodulators
A diverse class of proteins that boost the immune system. Many are cell growth factors that accelerate the production of specific cells that are important in mounting an immune response in the body. These proteins are being investigated for use in possible cures for cancer.
Immunotoxins
Specific monoclonal antibodies that have a protein toxin molecule attached. The monoclonal antibody is targeted against a tumor cell and the toxin is designed to kill that cell when the antibody binds to it. Immunotoxins have also been termed “magic bullets.”
Inducer
A molecule or substance that increases the rate of enzyme synthesis, usually by blocking the action of the corresponding repressor.
Interferon
A class of lymphokine proteins important in the immune response. The are three major types of interferon: alpha (leukocyte), beta (fibroblast), and gamma (immune). Interferons inhibit viral infections and may have anticancer properties.
Interleukin
A type of lymphokine whose role in the immune system is being extensively studied. Two types of interleukin have been identified. Interleukin 1 (IL-1), derived from macrophages, is produced during inflammation and amplifies the production of other lymphokines, notably interleukin 2 (IL-2). IL-2 regulates the maturation and replication of T lymphocytes.
Intron
In eukaryotic cells, a sequence of DNA that is contained in the gene but does not encode for protein. The presence of introns divides the coding region of the gene into segments called exons. See also Exon; Splicing.
In vitro
Literally, “in glass.” Performed in a test tube or other laboratory apparatus.
In vivo
In the living organism.
Isoenzyme (isozyme)
One of the several forms that a given enzyme can take. The forms may differ in certain physical properties, but function similarly as biocatalysts.
Isogenic
Of the same genotype.
Kidney plasminogen activator
A precursor to the enzyme urokinase that has bloodclotting properties.
Leukocyte
A colourless cell in the blood, lymph, and tissues that is an important component of the body’s immune system; also called white blood cell.
Library
A set of cloned DNA fragments.
Ligase
An enzyme used to join DNA or RNA segments together. They are called DNA ligase of RNA ligase, respectively.
Linkage
The tendency for certain genes to be inherited together due to their physical proximity on the chromosome.
Linkage group
A group of gene loci known to be linked; a chromosome. There are as many linkage groups as there are homologous pairs of chromosomes. See synteny.
Linkage map
An abstract map of chromosomal loci, based on recombinant frequencies.
Linker
A fragment of DNA with a restriction site that can be used to join DNA strands.
Lipoproteins
A class of serum proteins that transport lipids and cholesterol in the blood stream. Abnormalities in lipoprotein metabolism have been implicated in certain heart diseases.
Locus (Plural loci)
The position of a gene, DNA marker or genetic marker on a chromosome. See gene locus.
Lymphocyte
A type of leukocyte found in lymphatic tissue in the blood, lymph nodes, and organs. Lymphocytes are continuously made in the bone marrow and mature into antibody-forming cells. See also B lymphocytes; T lymphocytes.
Lymphokine
A class of soluble proteins produced by white blood cells that play a role, as yet not fully understood, in the immune response. See also Interferon; Interleukin.
Lymphoma
Form of cancer that affects the lymph tissue.
Lysis
Breaking apart of cells.
Lysozyme
An enzyme present in, for example, tears, saliva, egg whites and some plant tissues that destroys the cells of certain bacteria.
Macrophage
A type of white blood cell produced in blood vessels and loose connective tissues that can ingest dead tissue and cells and is involved in producing interleukin 1. When exposed to the lymphokine “macrophage-activating factor,” macrophages also kill tumor cells. See also Phagocyte.
Macrophage-activating factor
An agent that stimulates macrophages to attack and ingest cancer cells.
Marker
Any genetic element (locus, allele, DNA sequence or chromosome feature) which can be readily detected by phenotype, cytological or molecular techniques, and used to follow a chromosome or chromosomal segment during genetic analysis. See centromere marker; chromosome marker; DNA marker; genetic marker; inside marker; outside marker.
Medium
A liquid or solid (gel) substance containing nutrients needed for cell growth.
Meiosis
Process of cell reproduction whereby the daughter cells have half the chromosome number of the parent cells. Sex cells are formed by meiosis. Cf. Mitosis.
Messenger RNA (mRNA)
Nucleic acid that carries instructions to a ribosome for the synthesis of a particular protein.
Metabolism
All biochemical activities carried out by an organism to maintain life.
Microbial herbicides/pesticides
Microorganisms that are toxic to specific plant/insects. Because of their narrow host range and limited toxicity, these microorganisms may be preferable to their chemical counterparts for certain pest control applications.
Microbiology
Study of living organisms and viruses, which can be seen only under a microscope.
Microorganism
Any organism that can be seen only with the aid of a microscope. Also called microbe.
Mitosis
Process of cell reproduction whereby the daughter cells are identical in chromosome number to the parent cells. Cf. Meiosis.
Molecular genetics
Study of how genes function to control cellular activities.
Monoclonal antibody
Highly specific purified antibody that is derived from only one clone of cells and recognises only one antigen. See also Hybridoma; Myeloma.
mRNA
Messenger RNA.
Multigenic
Of hereditary characteristics, one that is specified by several genes.
Mutagen
A substance that induces mutations.
Mutant
A cell that manifest new characteristics due to a change in its DNA.
Mutation
A change in the genetic material of a cell.
Muton
The smallest element of a chromosome whose alteration can result in a mutation or a mutant organism.
Myeloma
A type of tumor cell that is used monoclonal antibody technology to form hybridomas.
Natural active immunity
Immunity that is established after the occurrence of a disease.
Natural killer (NK) cell
A type of leukocyte that attacks cancerous or virus-infected cells without previous exposure to the antigen. NK cell activity is stimulated by interferon.
Natural passive immunity
Immunity conferred by the mother on the foetus or newborn.
Nitrogen fixation
A biological process (usually associated with plants) whereby certain bacteria convert nitrogen in the air to ammonia, thus forming a nutrient essential for growth.
Nuclease
An enzyme that, by cleaving chemical bonds, breaks down nucleic acids into their constituent nucleotides. See also Exonuclease.
Nucleic acid
Large molecules, generally found in the cell’s nucleus and/or cytoplasm, that are made up of nucleotide bases. The two kinds of nucleic acid are DNA and RNA.
Nucleotide base
See Base.
Nucleotides
The building blocks of nucleic acids. Each nucleotide is composed of sugar, phosphate, and one of four nitrogen bases. If the sugar is ribose, the nucleotide is termed a “ribonucleotide,” whereas deoxyribonucleotides have deoxyribose as the sugar component. The sequence of the nucleotides within the nucleic acid determines, for example, the amino acid sequence of an encoded protein.
Nucleus
The structure within eukaryotic cells that contains chromosomal DNA.
Oligodeoxyribonucleotide
A molecule consisting of a small number (about two to a few tens) of nucleotides linked sugar to phosphate in a linear chain.
Oncogene
Any of a family of cellular DNA sequences which possess the potential to become malignant by undergoing alteration. There are 4 groups of viral and non-viral onc genes: protein kinases, GTPases, nuclear proteins, and growth factors.
Oncogenic
Cancer causing.
Oncology
Study of tumors.
Open reading frame
A nucleotide sequence beginning with a start (AUG) codon, continuing in register with amino acid-encoding codons, and ending with a stop codon.
Operator
A region of the chromosome, adjacent to the sequences encoding the gene product, where a repressor protein binds to prevent transcription.
Operon
Sequence of genes responsible for synthesising the enzymes needed for biosynthesis of a molecule. An operon is controlled by an operator gene and a repressor gene.
Opsonin
An antibody that renders bacteria and other antigenic material susceptible to destruction by phagocytes.
Organic compound
A compound containing carbon.
Passive immunity
Immunity acquired from receiving preformed antibodies.
Pathogen
Disease-causing organism.
Peptide
Two or more amino acids joined by a linkage called a peptide bond.
Phage
See Bacteriophage.
Phagocyte
A type of white blood cell that can ingest invading microorganisms and other foreign material. See also Macrophage.
Phenotype
Observable characteristics, resulting from interaction between an organism’s genetic make-up and the environment. Cf. Genotype
Photosynthesis
Conversion by plants of light energy into chemical energy, which is then used to support the plants’ biological processes.
Plasma
The fluid (noncellular) fraction of blood.
Plasmapheresis
A technique used to separate useful factors from blood.
Plasmid
A small circular form of DNA that carries certain genes and is capable of replicating independently in a host cell.
Pleiotropic
Genes or mutations that result in the production of multiple effects at the phenotypic level. It is the consequence of the fact that biochemical pathways starting from different genes intersect in many places, inhibiting, deflecting, and variously modifying each other. Introduced genes may also insert into sites that effect phenotypic changes other than the one desired.
Polyclonal
Derived from different types of cells.
Polymer
A long molecule of repeated subunits.
Polymerase
General term for enzymes that carry out the synthesis of nucleic acids.
Polymerase chain reaction (PCR)
A technique used for enzymatic in vitro amplification of specific DNA sequences without utilising conventional procedures of molecular cloning. It allows the amplification of a DNA region situated between two convergent primers and utilises oligonucleotide primers that hybridise to opposite strands. Primer extension proceeds inward across the region between the two primers. The product of DNA synthesis of one primer serves as a template for the other primer; repeated cycles of DNA denaturation, annealing of primers, and extension result in an exponential increase in the number of copies of the region bounded by the primers.
Polypeptide
Long chain of amino acids joined by peptide bonds.
Probe
See DNA probe.
Prokaryote
A cellular organism (e.g., bacterium, blue-green algae) whose DNA is not enclosed within a nuclear membrane. Cf. Eukaryote.
Promoter
A DNA sequence that is located near or even partially within encoding nucleotide sequences and which controls gene expression. Promoters are required for binding of RNA polymerase to initiate transcription.
Prophage
Phage nucleic acid that is incorporated into the host’s chromosome but does not cause cell lysis.
Protein
A molecule composed of amino acids. There are many types of proteins, most carrying out functions essential for cell growth.
Protein A
A protein produced by the bacterium Staphylococcus aureus that specifically binds antibodies. It is useful in the purification of monoclonal antibodies.
Protoplast
The cellular material that remains after the cell wall has been removed.
Pure culture
In vitro growth of only one type of microorganism.
Radioimmunoassay
A technique for quantifying a substance by measuring the reactivity of radioactively labelled forms of the substance with antibodies.
Reagent
Substance used in a chemical reaction, often for analytical purposes.
Recombinant DNA (rDNA)
The DNA formed by combining segments of DNA from two or more different sources or different regions of a genome.
Regeneration
Laboratory technique for forming a new plant from a clump of plant cells.
Regulatory gene
A gene that acts to control the protein-synthesising activity of other genes.
Replication
Reproduction or duplication, as of an exact copy of a strand of DNA.
Replicon
A segment of DNA (e.g., chromosome or plasmid) that can replicate independently.
Repressor
A protein that binds to an operator adjacent to a structural gene, inhibiting transcription of the gene.
Restriction enzyme
An enzyme that recognises a specific DNA nucleotide sequence, usually symmetrical, and cuts the DNA within or near the recognised sequence. This may create a gap into which new genes can be inserted.
Reticuloendothelial system
The system of macrophages, which serves as an important defense system against disease.
Retrovirus
An animal virus that contains the enzyme reverse transcriptase. This enzyme converts the viral RNA into DNA, which can combine with the DNA of the host cell and produce more viral particles.
Rheology
Study of the flow of matter such as fermentation liquids.
Rhizobium
A class of microorganisms that converts atmospheric nitrogen into a form that plants can utilise for growth. Species of this microorganism grow symbiotically on the roots of certain legumes such as peas, beans, and alfalfa.
RIA (Radioimmunoassay)
A diagnostic test using antibodies to detect trace amounts of substances. Such tests are useful in biomedical research to study how drugs interact with their receptors.
Ribonucleic acid (RNA)
A molecule similar to DNA that functions primarily to decode the instructions for protein synthesis that are carried by genes. See also Messenger RNA; Transfer RNA.
Ribosome
A cellular component, containing protein and RNA, that is involved in protein synthesis.
Ribozyme
Any of the RNA molecules possessing catalytic activity and acting as biological catalysts.
RNA
Ribonucleic acid.
Scale-up
Transition from small-scale production to production of large industrial quantities.
Selective medium
Nutrient material constituted such that it will support the growth of specific organisms while inhibiting the growth of others.
Sequence tagged site (STS)
Short (200 to 500 base pairs) DNA sequence that has a single occurrence in the human genome and whose location and base sequence are known. Detectable by polymerase chain reaction, STSs are useful for localising and orienting the mapping and sequence data reported from many different laboratories and serve as landmarks on the developing physical map of the human genome. Expressed sequence tags (ESTs) are STSs derived from cDNAs.
Serology
Study of blood serum and reaction between the antibodies and antigens therein.
Signal sequence
The N-terminal sequence of a secreted protein, which is required for transport through the cell membrane.
Single-cell protein
Cells or protein extracts from microorganisms, grown in large quantities for use as protein supplements. Single cell protein is expected to have a nutritionally favourable balance of amino acids.
Site-specific recombination
A crossover event, such as the integration of phage lambda, that requires homology of only a very short region and uses an enzyme specific for that recombination. Recombination occurring between two specific sequences that need not be homologous; mediated by a specific recombination system.
snRNP
Small nuclear ribonucleoprotein (RNA plus protein) particle. Component of the spliceosome, the intron-removing apparatus in eukaryotic nuclei.
Somatic cells
Cells other than sex or germ cells.
Splicing
The removal of introns and joining of exons to form a continuous coding sequence in RNA.
Strain
A pure-breeding lineage, usually of haploid organisms, bacteria, or viruses.
Stringent response
A translational control mechanism of prokaryotes that represses tRNA and rRNA synthesis during amino acid starvation.
Structural gene
A gene that codes for a protein, such as an enzyme.
Substrate
Material acted on by an enzyme.
Suppressor gene
A gene that can reverse the effect of a mutation in other genes.
Synteny
All loci on one chromosome are said to be syntenic (literally on the same ribbon). Loci may appear to be unlinked by conventional genetic tests for linkage but still be syntenic.
Synteny test
A test that determines whether two loci belong to the same linkage group (i.e. are syntenic) by observing concordance (occurrence of markers together) in hybrid cell lines.
Template
A molecule that serves as the pattern for synthesising another molecule.
Therapeutics
Compounds that are used to treat specific diseases or medical conditions.
Thymus
A lymphoid organ in the lower neck, the proper functioning of which in early life is necessary for development of the immune system.
Tissue culture
In vitro growth in nutrient medium of cells isolated from tissue.
Tissue plasminogen activator (tPA)
A protein produced in small amounts in the body that aids in dissolving blood clots.
T lymphocytes (T-cells)
White blood cells that produced in the bone marrow but mature in the thymus. They are important in the body’s defense against certain bacteria and fungi, help B lymphocytes make antibodies, and help in the recognition and rejection of foreign tissues. T lymphocytes may also be important in the body’s defense against cancers.
Toxin
A poisonous substance produced by certain microorganisms.
Transcription
Synthesis of messenger (or any other) RNA on a DNA template.
Transduction
Transfer of genetic material from one cell to another by means of a virus or phage vector.
Transfection
Infection of a cell with nucleic acid from a virus, resulting in replication of the complete virus.
Transfer RNA (tRNA)
RNA molecules that carry amino acids to sites on ribosomes where proteins are synthesised.
Transformation
Change in the genetic structure of an organism by the incorporation of foreign DNA.
Transgenic organism
An organism formed by the insertion of foreign genetic material into the germ line cells of organisms. Recombinant DNA techniques are commonly used to produce transgenic organisms.
Translation
Process by which the information on a messenger RNA molecule is used to direct the synthesis of a protein.
Transposon
A segment of DNA that can move around and be inserted at several sites in the genome of a cell possibly altering expression. The first to be described was the Ac/Ds system in maize shown by McClintock to cause unstable mutations.
tRNA
See transfer RNA.
Tumor necrosis factor
A cytokine with many actions including the destruction of some types of tumor cells without affecting healthy cells. However, hopes for their usefulness in cancer therapy have been dampened by toxic effects of the treatment. They are now being engineered for selective toxicity for cancer cells.
Tumor suppressor gene
Any of a category of genes that can suppress transformation or tumorigenicity (probably ordinarily involved in normal control of cell growth and division).
Vaccine
A preparation that contains an antigen consisting of whole disease-causing organisms (killed or weakened), or parts of such organisms, and is used to confer immunity against the disease that the organism causes. Vaccine preparation can be natural, synthetic, or derived by recombinant DNA technology.
Vector
The agent (e.g., plasmid or virus) used to carry new DNA into a cell.
Virion
An elementary viral particle consisting of genetic material and a protein covering.
Virology
Study of viruses.
Virulence
Ability to infect or cause disease.
Virus
A submicroscopic organism that contains genetic information but cannot reproduce itself. To replicate, it must invade another cell and use parts of that cell’s reproductive machinery.
White blood cells
See Leukocytes.
Wild type
The form of an organism that occurs most frequently in nature.
Yeast
A general term for single-celled fungi that reproduce by budding. Some yeasts can ferment carbohydrates (starches and sugars), and thus are important in brewing and baking.