Glossary of terms in biotechnology

This leaflet is designed to help those who would like to know more about biotechnology but have been intimidated by unfamiliar words. Of course, our list is not exhaustive. We have included words that are frequently encountered in literature intended for the general public, but have left out more esoteric terms. We have avoided lengthy or highly technical definitions, and have concentrated on conveying the meanings of words as they are commonly used.

A

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.
Aerobic: Needing oxygen for growth.
Agrobacterium: A bacterium containing a plasmid that is useful in plant genetic engineering.
Allele: Any of several alternative forms of a gene.
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.
Anaerobic: Growing in the absence of oxygen.
Antibiotic: Chemical substance formed as a metabolic by-product 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.
Antigen: A substance that, when introduced into the body, induces an immune response by a specific antibody.
Antiserum: Blood serum containing specific antibodies against an antigen. Antisera are used to confer passive immunity to many diseases.
Attenuated: Weakened; with reference to vaccines, made from pathogenic orgainsms that have been treated so that they are unable to cause disease.
Autoimmunity: A condition in which the body mounts an immune response against one of its own organs or tissues.

B

Bacteriophage: Virus that lives in and kills bacteria. Also called phage.
Bacterium: Any of a large group of microscopic organisms with a very simple cell structure. Some manufacture their own food, some live as parasites on other organisms, and some live on decaying matter. (See Prokaryote)
Base: On the DNA molecule, one of the four chemical units that, according to their order and pairing, 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 the nucleic acid molecule that bond together. The bases can pair in only one way: adenine with thymine (DNA) or uracil (RNA), and guanine with cytosine.
Bioassay: Determination of the effectiveness of a compound by measuring its effect on animals, tissues, or organisms in comparison with a standard preparation.
Biocatalyst: In bioprocessing, an enzyme or microorganism that activates or speeds up a biochemical reaction.
Biochip: Electronic device that uses organic molecules to form a semiconductor.
Bioconversion: Chemical restructuring of raw materials by using a biocatalyst.
Biodegradable: Capable of being broken down by the action of microorganisms or enzymes.
Biological oxygen demand (BOD): The amount of oxygen used for growth by organisms in water that contains organic matter. Commonly used as an indicator of pollution levels.
Biomass: The mass of biological material (e.g. microbial cells or plants), commonly used to refer to agricultural feedstocks. In microbiology, refers to mass of microbial cells in growth studies.
Biosensor: Device in which powerful recognition systems of biological chemicals (enzymes, antibodies) are coupled to microelectronics to enable low-level detection of substances such as sugars and proteins in body fluids, pollutants in water and gases in air.
Biotechnology: Development of products by a biological process. Production may be carried out by using intact organisms, such as yeasts and bacteria, or by using natural substances (e.g. enzymes) from organisms.
B lymphocytes (B-cells): A class of lymphocytes, released from the bone marrow, which produce antibodies.

C

Callus: A cluster of undifferentiated plant cells that can, in some species, be induced to form a whole plant.
Carcinogen: Cancer-causing agent.
Cell: The smallest structural unit of living organisms that is able to grow and reproduce independently.
Cell culture: Growth of cells under laboratory conditions.
Cell fusion: See Fusion
Cell line: Cells which grow and replicate continuously outside the living organism.
Chemostat: Growth chamber that keeps a bacterial culture at a specific volume and rate of growth by continually adding fresh nutrient medium while removing spent culture.
Chromosomes: Threadlike components in the cell that contain DNA and proteins. Genes are carried on the chromosomes.
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 to the parent.
Codon: A sequence of three nucleotide bases that specifies an amino acid or represents a signal to stop or start a function.
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.
Complementary DNA (cDNA): DNA synthesized from a messenger RNA 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 hybridization studies.
Copy number: Refers to the number of molecules of the plasmid per molecule of chromosome.
Culture: As a noun, cultivation of living organisms 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-: Referring to cell or cell plasm.
Cytoplasm: Cellular material that is within the cell membrane and surrounds the nucleus.

D

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.
Diagnostic: A product used to diagnose a 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 specialized in form and function.
Diploid: A cell with two complete sets of chromosomes. Cf.Haploid.
DNA: See Deoxyribonucleic acid.
DNA cloning: The process whereby fragments of DNA from any source can be amplified many times by inserting them into a plasmid or a bacterial virus (bacteriophage) and then growing these in bacterial or yeast cells.
DNA probe: A molecule (usually a nucleic acid) that has been labeled with a radioactive isotope, dye, or enzyme and is used to locate a particular nucleotide sequence or gene on a DNA molecule.
DNA sequence: The order of nucleotide bases in the DNA 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.

E

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.
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 well characterized.
Eukaryote: A cell or organism containing a true nucleus, with a well-defined membrane surrounding the nucleus. All organisms except bacteria, 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 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.

F

Feedstock: The raw material used for chemical or biological processes.
Fermentation: A process of growing micro-organisms 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.
Fungus: (Plural: Fungi) A Eukaryote possessing a cell wall. Fungi cannot conduct photosynthesis and they feed on organic mattter. Fungi include mushrooms and moulds.
Fusion: Joining of the membrane of two cells, thus creating a daughter cell that contains the nuclear material from parent cells. Used in making hybridomas. (See Protoplast)

G

Gene: A segment of chromosome. Some genes direct the synthesis of proteins, while others have regulatory functions.
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 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 acids 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.
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.
Germplasm: The total genetic variability, represented by germ cells or seeds, available to a particular population of organisms.
Growth hormone (also called somatotropin): A protein produced by the pituitary gland that is involved in cell growth. Human growth hormone is used clinically to treat dwarfism. Various animal growth hormones can be used to improve milk production as well as to produce a leaner variety of meat.

H

Haploid: A cell with half the usual number of chromosomes, or only one chromosome set. Sex cells are haploid. Cf. diploid.
Heredity: Transfer of genetic information from parent cells to progeny.
Homologous: Corresponding or alike in structure, position, or origin.
Hormone: A chemical, often a polypeptide, that acts as a messenger, relaying instructions to stop or start certain physiological activities. Hormones are synthesized 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.
Hybridization: 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.

I

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.
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 flluids (blood, urine, etc). It is currently being investigated as a way of locating tumor cells in the body.
Immunogen: Any substance that can elicit an immune response.
Immunoglobulin: General name for proteins that function as antibodies.
Immunology: Study of all phenomena related to the body's response to antigenic challenge (i.e. immunity, sensitivity, and allergy).
Immunotoxins: Monoclonal antibodies that have a protein toxin molecule attached. The molecule is targeted against a tumour cell and the toxin is designed to kill that cell.
Interferon: A class of proteins important in the immune response. Interferons inhibit viral infections and may have anticancer properties.
Intron: In eukaryotic cells, a sequence of DNA that is contained in the gene but does not encode for protein.
In vitro: Literally, "in glass." Performed in a test tube or other laboratory apparatus.
In vivo: In the living organism.

L

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 or RNA ligase, respectively.
Linkage: The tendency for certain genes to be inherited together due to their physical proximity on the chromosome.
Lymphokine: A class of soluble proteins, produced by white blood cells, that play a role in the immune response.
Lysis: Breaking apart of cells.

M

Medium: A mixture of 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 instruction 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 plants/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 that 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 recognizes only one antigen. See also Hybridoma; Myeloma.
mRNA: Messenger RNA.
Mutagen: A substance that induces mutations.
Mutant: A cell that manifests new characteristics due to a change in its DNA.
Mutation: A sudden random change in the genetic material of a cell.
Myeloma: A type of tumor cell that is used in monoclonal antibody technology to form hybridomas.

N

Nuclease: An enzyme that, by cleaving chemical bonds, breaks down nucleic acids into their constituent nucleotides. See also Exonuclease.
Nucleic acids: 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. The sequence of the bases within the nucleic acid determines which proteins will be made.
Nucleus: The structure within eukaryotic cells, bounded by a membrane, that contains an organism's chromosomes.

O

Oligonucleotide: A polymer consisting of a small number (about two to ten) of nucleotides.
Oncogene: Gene thought to be capable of producing cancer.
Operator gene: A region of the chromosome, adjacent to the operon, where a repressor protein binds to prevent transcription of the operon.
Operon: Sequence of genes responsible for synthesizing the enzymes needed for biosynthesis of a molecule. An operon is controlled by an operator gene and a repressor gene.

P

Pathogen: Disease-causing organism.
Peptide: Two or more amino acids joined by a linkage called a peptide bond.
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.
Plasmid: A small circular form of DNA that carries certain genes and is capable of replicating independently in a host cell.
Polyclonal: Derived from different types of cells. Cf. Monoclonal.
Polymer: A long molecule of repeated subunits.
Polymerase: General term for enzymes that carry out the synthesis of nucleic acids.
Polypeptide: Long chain of amino acids joined by peptide bonds.
Prokaryote: An organism (e.g. bacterium, virus, blue-green alga) whose DNA is not enclosed within a nuclear membrane. Cf. Eukaryote.
Promoter: A DNA sequence that is located in front of a gene and controls gene expression. Promoters are required for binding of RNA polymerase to initiate transcription.
Protein: A molecule composed of amino acids. There are many types of proteins, all carrying out a number of different functions essential for cell growth.
Protoplast: The cellular material that remains after the cell wall has been removed.
Pure culture: In vitro growth of only one type of microorganism.

R

Radioimmunoassay (RIA): 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.
Recombinant DNA (rDNA): The DNA formed by combining segments of DNA from different types of organisms.
Regulatory gene: A gene that acts to control the protein-synthesizing activity of other genes.
Replication: Reproduction or duplication, as of an exact copy of a strand of DNA.
Repressor: A protein that binds to an operator adjacent to a structural gene, inhibiting transcription of that gene.
Restriction enzyme: An enzyme that breaks DNA in highly specific locations, creating gaps into which new genes can be inserted.
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.
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 sythesis.
Ribozyme: An enzyme made of RNA rather than protein. "Designer" ribozymes which can cut RNA molecules at specific points are known as "gene shears". RNA; Ribonucleic acid.

S

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.
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.

T

Template: A molecule that serves as the pattern for synthesizing another molecule.
Therapeutics: Compounds that are used to treat specific diseases or medical conditions.
Tissue culture: In vitro growth in nutrient medium of cells isolated from tissue.
T lymphocytes (T-cells): White blood cells that are produced in the bone marrow but mature in the thymus. They are important in the body's defences 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 defence against cancers.
Toxin: A poisonous substance produced by certain microorganisms.
Transcription: Synthesis of messenger (or any other) RNA on a DNA template.
Transfer RNA (tRNA): RNA molecules that carry amino acids to sites on ribosomes where proteins are synthesized.
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. tRNA; Transfer RNA.

V

Vaccine: A preparation that contains an antigen consisting of whole disease-causing orgainsms (killed or weakened), or parts of such organisms, and is used to confer immunity against the disease that the organisms cause. Vaccine preparations 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.
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.

W

Wild type: The form of an organism that occurs most frequently in nature.

Y

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.

Most definitions based on those in Biotechnology at Work Glossary of Terms, published by Industrial Biotechnology Association, 1625 K Street, N.W., Suite 1100, Washington DC 20006, USA. ABA acknowledges with thanks IBA's permission to reproduce this material.

Last revision: 16 Apr 96

Original leaflets produced by Deakin University, School of Computing and Mathematics for Australian Biotechnology Association Ltd.

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