Joining segment (Abbreviation: J). A small DNA segment that links genes in order to yield a functional gene encoding an immunoglobulin.
Juvenility Early phase of development in which an organism is incapable of sexual reproduction.
Kanamycin An antibiotic of the aminoglycoside family that inhibits translation by binding to the ribosomes. Important as a substrate for selection of plant transformants.
Kartagener’s syndrome A genetic disorder in which the heart and other internal organs are on the opposite side of the body to the normal location for the organs.
Karyogamy The fusion of nuclei or nuclear material that occurs at fertilization during sexual reproduction.
Karyogram A diagrammatic representation of the full chromosome set of a species, highlighting characteristic physical features of individual chromosomes.
Karyotype The chromosome constitution of a cell, an individual, or of a related group of individuals, as defined both by the number and the morphology of the chromosomes, usually in mitotic metaphase; chromosomes arranged in order of length and according to position of centromere; also, the abbreviated formula for the chromosome constitution, such as 47, + 21 for human trisomy-21 (Down’s syndrome).
Keratinocytes A type of skin cell that makes up 95 percent of the epidermis. They contain the keratin proteins that make up a large part of nail, hair, and skin.
Killer T cell T cells that kill cells displaying recognized antigens.
Kinetochore Structure at the centromere of eukaryotic chromosomes. The kinetochore consists of inner and outer electron dense plates and a central zone containing repetitive DNA elements. Kinetochores are involved in the control of chromosome movement in cell division.
Klinefelter’s syndrome A genetic growth disorder in males, resulting in small testes, enlarged breasts, and failure to produce sperm. It is caused by the presence of an extra sex chromosome.
Knockout A mutant individual, in which a single functionalgene has been replaced by a non-functional form of the gene. Used to understand gene function via the comparison of the phenotypes of wild type and knockouts.
Label A compound or atom that is attached to, or incorporated into, another molecule in order to allow detection of the latter’s presence. Commonly, labels exploit radioactivity, fluorescence or antigenicity. Synonym: tag.
Labelled probe Molecules with special properties, like radioactivity, used to search for, and highlight, other specific molecules in a sample.
Labelling The process of attaching or inserting a label into a molecule. Most often in the context of nucleic acids or proteins.
Lag phase 1. The state of apparent inactivity preceding a response to a treatment; also called a latent phase. 2. The initial growth phase, during which cell number remains relatively constant, prior to the onset of rapid cell division.
Lagging strand The strand of DNA that is synthesized discontinuously during replication (because DNA synthesis can proceed only in the 5′?3′ direction). See: Okazaki fragment.
Land-based grow-out systems (In aquaculture) Refers to a land rearing facility for aquatic organisms.
Leading strand The strand of DNA that is synthesized continuously during replication.
Lethal allele A mutant form of a gene that, in the homozygous state, is fatal.
Lethal gene See: lethal allele.
Leukocytes White blood cell, up to 0.02 mm in diameter, of which there are normally 4-11 million per millilitre of human blood.Leukocytes or the WBCs are an essential part of our immune system. Investigate this site to know how these cells function in our body. They fight the infections in the body and this they do by attacking the germs, virus and bacteria that invade our body. The WBC originates in the bone marrow. These then circulate through the bloodstream. There are several kinds, all involved in the body’s defence mechanisms. Granulocytes have granules in their cytoplasm; monocytes ingest and feed on bacteria and other micro-organisms that cause infection; lymphocytes include the B cells that are involved with the production of antibodies.
Life-cycle The sequence of events from a given developmental stage in one generation to the same stage in the following generation. In sexually reproduced organisms, the starting point is the fusion of gametes to form the zygote.
Life Sciences Industry – Organizations in the fields of biotechnology, pharmaceuticals, biomedical technologies, life systems technologies, nutraceuticals, cosmeceuticals, food processing, environmental, biomedical devices. Also called: Life Sciences, Biological Sciences, Medical Supplies Industry, Health Care Supplies Industry, Medical Equipment Industry, Medical Devices Industry, Natural Sciences, Medical Devices, Life Science Industry, Medical Device Industry, Medical Products Industry, Health Care Equipment Industry, and Medical Instruments Industry
Lignans A small molecule (e.g. activators, substrates and inhibitors of enzyme activity) bound to a protein by non-covalent forces; an ion or a molecule that binds to another chemical entity to form a larger complex.
Lineage A group of individuals, related by common descent, e.g. an in vitro cell line derived from a single cell.
Linear phase The growth phase during cell culture when cell number increases arithmetically. The linear phase follows a period of exponential growth.
Linearized vector A covalently closed circular DNA vector (typically a plasmid) which has been opened by restriction digestion to convert it to a linear molecule. In molecular cloning, DNA to be cloned is mixed with the linearized vector, and treated with ligase to join and recircularize the resulting hybrid molecule.
Linkage The tendency of a set of genes to be inherited together more often than would be expected if they were assorting independently. exists between two genes when they are located sufficiently close to one another on the same chromosome that a proportion of gametes is produced without crossing-over occurring between them.
Linkage map A linear or circular diagram that shows the relative positions of genes on a chromosome as determined by recombination fraction.
Lipid Any of a group of fats or fat-like compounds insoluble in water and soluble in fat solvents.
Liposome A synthetic microscopic spherical structure consisting of a phospholipid bilayer membrane containing a user-defined aqueous solution. Liposomes can be used to transport relatively toxic drugs into diseased cells, where they can exert their maximum effect. DNA molecules may be entrapped in, or bound to the surface of, the vesicles, and subsequent fusion of the liposome with the cell membrane will deliver the DNA into the cell. Liposomes have been used to develop an efficient transfection procedure for Streptomyces bacteria.
Lipoprotein Molecules that transport fatty compounds, like cholesterol, in the blood.
Live vaccine A living, non-virulent form of a pathogenic micro-organism or virus used to elicit an antibody response for the protection against infection by a virulent form of the same pathogen.
Living modified organism (Abbreviation: LMO). “Living organism that possess a novel combination of genetic material obtained through the use of modern biotechnology” (Convention on Biological Diversity). Synonym of GMO, but restricted to organisms that can endanger biological diversity.
Low-density lipoprotein(s) A lipoprotein that is high in cholesterol and low in protein content. It carries the cholesterol to cells and tissues and is associated with heart disease.
Lymphocyte White blood cells that are important components of the immune system of vertebrates. See: B cell, T cell.
Lymphokine Generic name for proteins that are released by lymphocytes to act on other cells involved in the immune response. The term includes interleukins and interferons. A sub-class of cytokines.
Lymphoma Cancer originating in the lymph nodes, spleen and other lympho-reticular sites.
Lysis The destruction or breakage of cells either by viruses or by chemical or physical treatment.
Lysosome A membrane-bound sac within the cytoplasm of animal cells that contains enzymes responsible for the digestion of material in food vacuoles, the dissolution of foreign particles entering the cell and, on the death of the cell, the breaking down of all cell structures. The digestive system of the cell.
Lysozyme A naturally occurring enzyme extracted from egg white protein and other animal and plant sources, which attacks the cell wall of gram-positive bacteria leading to cell lysis and death.
Lytic A phase of the virus life cycle during which the virus replicates within the host cell, releasing a new generation of viruses when the infected cell undergoes lysis.
Lytic cycle The steps in viral production that lead to cell lysis.
Macromolecule Any high molecular weight molecule. Often used as a synonym for polymers.
Macronutrient A major chemical element essential for normal growth and development. In tissue culture media, macronutrients are those required in concentrations above 0.5 millimole/litre.
Macrophage Large white blood cells that ingest foreign substances and display on their surfaces antigens which are recognized by other cells of the immune system.
Mad cow disease Colloquial term for bovine spongiform encephalopathy.
Marker An identifiable DNA sequence that is inherited in Mendelian fashion, and which facilitates the study of inheritance of a trait or a linked gene.
Marker gene A gene of known function or known location, used for marker-assisted selection or genetic studies.
Mash Mixture of boiled grain, bran or other substances (including bacteria) for brewing or production purposes.
Maturation The formation of gametes or spores.
Maximum residue levels Criteria that govern the safe maximum levels of pesticide residues on goods produced for consumption.
Medium/media A substance used to provide nutrients for in vitro (outside the body) cell growth. It may be liquid or solid.
Meiosis The two-stage process in sexual reproduction by which the chromosome number is reduced from the somatic to the haploid number. The first division, in which homologous chromosomes pair and exchange genetic material, is followed by amitotic division. The nucleus divides twice, but the chromosomes only once, generating haploid nuclei, which develop into the gametes (egg and sperm in animals; egg and s in plants).
Memory cell Long-lived B cells and T cells that mediate rapid secondary immune responses to a previously encountered antigen.
Mendel’s Laws Two laws summarizing Gregor Mendel’s theory of inheritance. The Law of Segregation states that each hereditary characteristic is controlled by two ‘factors’ (now called alleles), which segregate and pass into separate germ cells. The Law of Independent Assortment states that pairs of ‘factors’ segregate independently of each other when germ cells are formed.
Mesoderm The middle germ layer that forms in the early animal embryo and gives rise to parts such as bone and connective tissue.
Messenger RNA Abbreviation: mRNA.
Metabolism The biochemical processes whereby nutritive material is converted to living matter, or aids in building living matter, or by which complex substances and food are broken down into simple substances.
Metabolite A low-molecular-weight biological compound that is usually synthesized enzymically.
Metacentric chromosome A chromosome in which thecentromere is located in the middle and, consequently, the chromosome arms are of about equal length.
Metaphase Stage ofmitosis or meiosis (following prophase and preceding anaphase) during which the chromosomes, or at least the kinetochores, lie in the central plane of the spindle. The stage of maximum chromosome condensation, at which karyotypes are generally described. In the first division of meiosis, metaphase represents the stage at which meiotic analysis is generally performed.
Metastasis The spread of cancer cells to previously unaffected organs.
Methionine A naturally occurring amino acid which is essential in the mammalian diet, providing both methyl groups and sulfur needed for normal metabolism.
Microalgae An ancient life form that produces oxygen. Almost all microalgae are unicellular.
Micro-array A large set of cloned DNA molecules immobilized as a compact and orderly pattern of sub-microlitre spots onto a solid matrix (typically a glass slide). Used to analyse patterns of gene expression, presence of markers, or nucleotide sequence. The major advantage of micro-arrays is the extent to which the process of genotyping can be automated, thereby enabling large numbers of individuals to be simultaneously genotyped at many loci. A similar approach may be used with other immobilized components for other purposes.
Microbe A microscopic organism including bacteria, fungi and viruses.
Microprojectile bombardment A technique for introducing new genes into cells. The gene is attached to tiny “bullets” made of tungsten or other metal. The tiny particles are then literally “shot” through the plasma membrane into plant cells by a “gene gun.”
Missense mutation A mutation that changes acodon for one amino acid into a codon specifying another amino acid.
Mitochondrial DNA (Abbreviation: mtDNA). A circular DNA found in mitochondria. In mammals, mtDNA makes up less than 1% of the total DNA, but in plants the amount is variable. It encodes rRNA and tRNA and some mitochondrial proteins (up to 30 in animals).
Mitochondrion (pl.: mitochondria) Organelle possessing its own DNA which appear in all eukaryotic cells (and never in prokaryotic cells) and produce adenosine triphosphate as an energy source for the cell via oxidative phosphorylation. Mitochondria contain many enzymes of the respiratory cycle, although most of these proteins are nuclear encoded.
Mitosis Splitting of replicated chromosomes, and the division of the cytoplasm to produce two genetically identical daughter cells. On the basis of the appearance of the chromosomes, it is separated into five stages: interphase, prophase, metaphase, anaphase and telophase.
Modifying gene A gene that affects the expression of some other gene.
Molecular biology The study of living processes at the molecular level.
Molecular cloning The biological amplification of a DNA sequence via the mitotic division of a host cell into which it has been transformed or transfected.
Molecular genetics The study of the expression, regulation and inheritance of genes at the level of DNA and its transcription products.
Molecular weight The sum of the atomic weights of all atoms in a molecule.
Molecule The stable union of two or more atoms; some organic molecules contain very large numbers of atoms.
Monoclonal antibody (Abbreviation: mAb). An antibody, produced by a hybridoma, directed against a single antigenic determinant of an antigen.
Monounsaturated fatty acid A fatty acid that contains one double bond in the hydrocarbon chain.
Mosaic viruses Viruses that cause leaf-mottling in plants.
mRNA Abbreviation for messenger RNA. The RNA molecule resulting from transcription of a protein-encoding gene, following any splicing (1). The information encoded in the mRNA molecule is translated into a gene product by the ribosomes.
Multiple alleles The existence of more than two alleles at a locus in a population.
Mutable gene A gene which has an unusually high rate of mutation.
Mutagen An agent or process capable of inducing mutations (e.g. irradiation, alkylating agents).
Mutagenesis Induction of heritable change(s) in the genetic constitution of a cell through alterations to its DNA.
Mutant An organism or an allele bearing a mutation. Usually applied when a characteristic change in phenotype can be recognized.
Mutation Any change in the genome with respect to a defined wild type. Can occur at the level of ploidy, karyotype, or nucleotide sequence. Most of the latter mutations are silent (i.e. cannot be associated with any change in phenotype), either because the DNA sequence affected is in the non-coding part of the genome, or because the specific change does not alter the function of a coding sequence.
Myeloma A plasma cell cancer.
Natural selection The differential survival and reproduction of organisms because of differences in characteristics that affect their ability to utilize environmental resources.
Necrosis Death of tissue evidenced by discolouration, dehydration and loss of organization.
Negative control system A mechanism by which a regulatory protein is required to turn off gene expression.
Nematode Slender, unsegmented worms, often parasitic. Also known as eelworm, especially when phytoparasitic.
Neurodegenerative disease Diseases caused by the irreversible deterioration of essential cell and tissue components of the nervous system.
Neurons Cells of the nervous system, which transmit nerve impulses (electrical signals) between cells.
Neurotransmitter A chemical that mediates the transmission of nerve impulses between neurons.
Neutral mutation A mutation that changes thenucleotide sequence of a gene, but has no observable effect on the fitness of the organism.
Nitrile herbicide Chemical class of herbicides used for post-emergent control of annual broadleaf weeds. Broken down by soil bacteria.
Non-selective (In herbicides) Lacking specificity. Lethal to many plant varieties, whether or not they are considered weeds.
Nonsense mutation A mutation which converts an amino-acid-specifyingcodon into a stop codon, e.g. a single base change from UAU to UAG generates the premature termination of the polypeptide chain at the position where a tyrosine was incorporated in the wild type.
Non-target organism/species Organisms that may be exposed to a given product or event, even though they are not the intended target.
Non-transformed Those cells which failed to incorporate foreign DNA into their genomes during an engineering attempt to add a gene(s).
Nopaline synthase An enzyme used as a genetic tag.
Novel/novel food New. In the context of food, the term often refers to genetically modified foods, foods developed using a new process (including the use of genetically modified organisms), or substances that have never been used as foods before.
Novel pollination mechanisms A process that involves the use of genetic modification to create a unique pollination environment where intentionally selected varieties of a crop must pollinate each other.
Novel traits A characteristic that has been intentionally selected, created or introduced into a distinct, stable population of the same species (animal or plant) through a specific genetic change.
Nuclear transfer A technology by which novel animals are generated by cloning a single diploid somatic cell. It involves inserting a single diploid cell from a culture of cells into an enucleated ovum. The resultant diploid ovum develops into an embryo that is placed in a recipient female, which gives birth to the cloned animal in the normal manner. Note that the term is somewhat of a misnomer, since it is a whole cell that is transferred, not just the nucleus.
Nuclease A class of largely bacterial enzymes that degrade DNA or RNA molecules by catalysing the cleavage of the phosphodiester bonds that link adjacent nucleotides. For deoxyribonuclease (DNAse) the substrate is DNA, for ribonuclease (RNAse) the substrate is RNA, and for S1 nuclease, the substrate is single-stranded DNA or RNA. Endonucleases cleave at internal sites in the substrate molecule, while exonucleases progressively cleave from the end of the substrate molecule. Nucleases have varying degrees of base-sequence specificity, the most specific being the restriction endonucleases.
Nucleic acid A macromolecule consisting of polymerized nucleotides. Two forms are found, DNA and RNA. Nucleic acids may be linear or circularized, and single- or double-stranded.
Nucleolus An RNA-rich nuclear organelle in the nucleus of eukaryotic cells, produced by a nucleolar organizer. It represents the storage place for ribosomes and ribosome precursors. The nucleolus consists primarily of ribosomal precursor RNA, ribosomal RNA, their associated proteins, and some, perhaps all, of the enzymatic equipment (RNA polymerase, RNA methylase, RNA cleavage enzymes) required for synthesis, conversion and assembly of ribosomes. Subsequently the ribosomes are transported to the cytoplasm.
Nucleoplasm The non-staining or slightly chromophilic, liquid or semi-liquid, ground substance of the interphase nucleus and which fills the nuclear space around the chromosomes and the nucleoli. Little is known of the chemical composition of this ground substance, which is not easily defined. Sometimes called “karyoplasm” when it is gel-like, and “karyolymph” when it is a colloidal fluid.
Nucleoside Abase (purine or pyrimidine) that is covalently linked to a 5-carbon (pentose) sugar. When the sugar is ribose, the nucleoside is a ribonucleoside; when it is 2-deoxyribose, the nucleoside is a deoxyribonucleoside.
Nucleotide A nucleoside with one or more phosphate groups linked at the 3′- or 5′-hydroxyl of a pentose sugar. When the sugar is ribose, the nucleotide is a ribonucleotide; when it is 2-deoxyribose, the nucleotide is a deoxyribonucleotide. RNA and DNA are polymers of, respectively, ribonucleoside 5′-monophosphates and deoxyribonucleoside 5′-monophosphates. Nucleotides containing the bases adenine, guanine and cytosine (A, G, C) occur in both DNA and RNA; thymine (T) occurs only in DNA, and uracil (U) only in RNA. Ribonucleoside mono-, di-, and triphosphates for which a specific base is not assigned are abbreviated NMP, NDP, and NTP, while deoxyribonucleoside mono-, di-, and tri-phosphates are abbreviated dNMP, dNDP, and dNTP. Otherwise, the “N” is replaced by the base letter abbreviation.
Nucleus A dense protoplasmic membrane-bound region of a eukaryotic cell that contains the chromosomes, separated from the cytoplasm by a membrane; present in all eukaryotic cells except mature sieve-tube elements and red blood cells.
Observable expression The observable properties of an organism, thought to be a result of the interaction of the organism’s genetic constitution with its environment.
Ocean pout Marcrozoarces americanus. A type of fish found in western North Atlantic Ocean.
Oilseeds Plant species whose seeds produce high oil content (20 – 50%). They include canola, soybeans, flax, cottonseed and corn.
Oligodendrocytes A class of glial cells. They provide insulating sheaths around neurons to prevent them from transmitting impulses to the wrong neuron.
Omega-3 fatty acids An unsaturated fatty acid that may reduce blood concentrations of triglycerides.
Oncogenesis The progression of cytological, genetic and cellular changes that culminate in the development of a tumour.
Onco-mouse A mouse that has been genetically modified to incorporate an oncogene, which acts as an animal model for studies of human cancer.
Operator The region of DNA that is upstream from a gene or genes and to which one or more regulatory proteins (repressor or activator) bind to control the expression of the gene(s).
Operon A functionally integrated genetic unit for the control of gene expression in bacteria. It consists of one or more genes that encode one or more polypeptide(s) and the adjacent site (promoter and operator) that controls their expression by regulating the transcription of the structural genes.
Organ A tissue or group of tissues that constitute a morphologically and functionally distinct part of an organism.
Organ culture The aseptic culture of complete living organs of animals and plants outside the body in a suitable culture medium. Animal organs must be small enough to allow the nutrients in the culture medium to penetrate all the cells.
Organelle A membrane-bounded specialized region within a cell, such as the mitochondrion or dictyosome, that carries out a specialized function in the life of a cell.
Organic crops Organic crop includes those that:
* prohibit the use of ionizing radiation in the preservation of food
* prohibit the use of genetically engineered or modified organisms
* encourages the maximum use of recycling
* encourages the maximum rotation of crops and promotion of biodiversity.
Organic toxin Toxins derived from bacteria and viruses, killed by chemical exposure, heat, or irradiation, which are incapable of causing disease. Also known as inactivated toxins.
Organism An individual living system, such as animal, plant or micro-organism, that is capable of reproduction, growth and maintenance.
Orphan receptor A receptor for which a cellular function or ligand has yet to be identified.
Outcrossing The transfer of a given gene or genes from a domesticated organism (e.g., crop plant) to a wild type (relative of plant).
P450 metabolism genes A specific group of chemical metabolism genes that produce the group of P450 enzymes.
Pairing The pairing of homologous chromosomes during the prophase of the first meiotic division. Pairing is the first prerequisite before crossing over and recombination can occur.
Pathogen A disease-causing organism (generally microbial: bacteria, fungi, viruses; but can extend to other organisms: e.g. nematodes etc.). Synonym: infectious agent.
Pathogenecity potential The potential to cause disease.
Pattern of clearance The method by which the body breaks down or disposes of infectious organisms or substances such as drugs (i.e. what major organs are involved, how long it stays in the system).
Peptide A sequence of amino acids linked by peptide bonds; a breakdown or build-up unit in protein metabolism. Typically used to describe low molecular weight species. See: polypeptide.
Peptide bond The chemical bond holding amino acid residues together in peptides and proteins. The (CO-NH) bond is formed by the condensation, with loss of a water molecule, between the carboxyl (-COOH) group of one amino acid and the amino (-NH2) of the next amino acid.
Phage Abbreviation for bacteriophage.
Phagocytes Immune system cells that ingest and destroy viruses, bacteria, fungi and other foreign substances or cells.
Phagocytosis The process by which foreign particles invading the body are engulfed and broken down by phagocytes.
Phenotype The visible appearance of an individual (with respect to one or more traits) which reflects the reaction of a given genotype with a given environment.
Phospholipid These molecules make up an important part of cell membranes. They are made up of a phosphate component and a lipid component. The lipid is water-hating, while the phosphate is water-loving. These properties help determine the structure of a membrane and facilitate the movement of material in and out of the cell.
Photosynthesis The fundamental chemical process in which green plants utilize the energy of sunlight or other light to convert carbon dioxide and water into carbohydrates, with the green pigment chlorophyll acting as the energy converter. This process releases oxygen and is the chief source of atmospheric oxygen.
Phytochemical Molecules characteristically found in plants.
Phytohormone A substance that stimulates growth or other processes in plants. Major species are auxins, abscisic acid, cytokinins, gibberellins and ethylene.
Pituitary gland A small gland attached to the hypothalamus. It is responsible for the secretion of a range of hormones, including growth hormones. Its secretions control the functioning of other glands in the body and is therefore sometimes called the “master” gland.
Plant breeders rights Legal protection of a new plant variety granted to the breeder or his successor in title. The effect of PBR is that prior authorization is required before the material can be used for commercial purposes.
Plaque A clear spot on an otherwise opaque lawn of bacteria, where cells have been lysed by phage infection
Plasma The fluid portion of the blood in which is suspended the white and red blood cells. Contains 8-9% solids, of which 85% is composed of the proteins fibrinogen, albumin, and globulin. The essential function of plasma is the maintenance of blood pressure and the transport of nutrients and waste.
Plasma cells Antibody-producing white blood cells derived from B lymphocytes.
Plasmid A circular self-replicating non-chromosomal DNA molecule found in many bacteria, capable of transfer between bacterial cells of the same species, and occasionally of different species. Antibiotic resistance genes are frequently located on plasmids. Plasmids are particularly important as vectors for genetic engineering.
Plastid A general term for a number of plant cell organelles which carry non-nuclear DNA. Includes the pigment-carrying bodies: 1. chloroplasts in leaves, 2. chromoplasts in flowers, and 3. the starch-synthesizing amyloplasts in seeds.
Platelet-activating factors Substances released by various cells, which cause platelets to clump together.
Platelet aggregation The naturally occurring process in the body during which platelets – disc shaped blood cells – clump together. The accumulation of platelets is essential in blood clotting at the site of an injury, for example. However, if there is platelet aggregation in a blood vessel, the result is a heart attack.
Pollination control mechanisms A system developed to manage plant fertilization activities.
Polygene One of a number of genes, each of small effect, which together act to determine the phenotype of a quantitative trait. The result is continuous variation in the trait and a seemingly non-Mendelian mode of inheritance.
Polymer A macromolecule synthesized by the chemical joining of many identical or similar monomers. For example, amino acids, monosaccharides and nucleotides give rise to proteins, polysaccharides and nucleic acids respectively. Water is eliminated between the monomers as they link to form chains. The individual monomer units condensed within a chain are often referred to as residues, a term which is also employed for the bases incorporated in polynucleotides.
Polymerase An enzyme that catalyses the formation of polymers from monomers. A DNA polymerase synthesizes DNA from deoxynucleoside triphosphates using a complementary DNA strand and a primer. An RNA polymerase synthesizes RNA from ribonucleoside triphosphates and a complementary DNA strand.
Polymerase chain reaction (Abbreviation: PCR) A widespread molecular biology procedure that allows the production of multiple copies (amplification) of a specific DNA sequence, provided that the base pair sequence of each end of the target is known. It involves multiple cycles of DNA denaturation, primer annealing, and strand extension, and requires a thermostable DNA polymerase, deoxyribonucleotides, and specific oligonucleotides (primers).
Polymorphism 1. The occurrence of allelic variation at a locus. Polymorphism in nucleotide sequences has provided powerful diagnostic tools. See: DNA diagnostics, microsatellites, restriction fragment length polymorphism. 2. The occurrence of two or more forms in a population.
Polypeptide A linear polymer composed of covalently linked amino acids. Each link is formed by a single peptide bond. Sometimes used as a synonym for protein, but also describes non-natural and low-molecular-weight polymers.
Polysaccharide A linear or branched polymer (e.g. starch, cellulose, etc.) composed of covalently linked monosaccharides, including cellulose, pectin and starch. Synonym: carbohydrate.
Polyunsaturated A molecule that contains two or more double or triple bonds.
Polyunsaturated fats & fatty acids Belonging to a class of animal or vegetable fats or oils containing multiple double or triple molecular bonds that are unsaturated by the incorporation of hydrogen; such fats and oils are associated with a low level of cholesterol in the blood.
Population genetics The branch of genetics that deals with frequencies of alleles and genotypes in breeding populations.
Positechâ„¢ The Positechâ„¢ gene is inserted into plant cells together with a gene of interest. When grown in the presence of mannose, which most plants can’t utilise as food, only those cells with the Positechâ„¢ gene grow. These cells can be regenerated into plants which carry the new trait.
Postemergence herbicide Herbicides that are applied after the weeds have emerged from the soil.
Precautionary principle The approach whereby any possible risk associated with the introduction of a new technology is avoided, until a full understanding of its impact on health, environment etc. is available. Particularly applied to the release of genetically modified organisms, since unlike many technologies, these cannot be recalled if problems arise.
Preclinical Extensive research of a new health-care product conducted before a clinical trial. Testing in the pre-clinical stage is done on laboratory models and animals.
Primer A short oligonucleotide annealed to a template of single-stranded DNA, providing a doubled stranded structure from which DNA polymerase will synthesize a new DNA strand to produce a duplex molecule.
Probe A labelled DNA or RNA sequence used to detect the presence of a complementary sequence by hybridization with a nucleic acid sample.
Product type (In Microbial Pest Control Products) Products fall into either of two product types:
* End Use Products (EP);
* and Manufacturing Products (MP).
End Use Products are the final products and must include labels and directions for use. Manufacturing Products are products that can either be used to manufacture an End Use Product or marketed alone as End Use Products with the correct labelling and approvals.
Programmed cell death See: apoptosis
Prokaryote A member of the large group of organisms, including bacteria and blue-green algae, in which the chromosome is not enclosed within a nucleus, but instead exists as a linear or circular strand. Prokaryotes do not undergo meiosis and do not have functional organelles such as mitochondria and chloroplasts.
Promoter 1. A short DNA sequence, usually upstream of (5′ to) the relevant coding sequence, to which RNA polymerase binds before initiating transcription. This binding aligns the RNA polymerase so that transcription will initiate at a specific site. The nucleotide sequence of the promoter determines the nature of the enzyme that attaches to it and the rate of RNA synthesis. 2. A chemical substance that enhances the transformation of benign cells into cancerous cells.
Propagation The duplication of a whole plant from a range of vegetative materials; adapted for in vitro culture as micropropagation.
Prophase The first stage of nuclear division. The stage during which chromosome pairing occurs in the first division of meiosis. In mitosis and the second division of meiosis, the chromosomes shorten and thicken as a result of coiling.
Proposed use patterns The suggested uses of a new product in terms of location, target organism(s), quantities, and other criteria dictated by the specific regulations.
Protease An enzyme that catalyses the hydrolysis of proteins, cleaving the peptide bonds that link amino acids in protein molecules. Synonym: peptidase.
Protein A macromolecule composed of one or more polypeptides, each comprising a chain of amino acids linked by peptide bonds.
Protein coat Refers to the protein coat or shell that surrounds the genome or protein core of the viral body. It is a major structural feature of many viruses.
Protein engineering Generating proteins with modified structures that confer novel properties such as higher catalytic specificity or thermal stability.
Protein sequencing The process of determining the amino acid sequence of a protein. Usually achieved following initially partial hydrolysis of the protein into smaller peptides by enzymatic digestion.
Protein synthesis The creation of proteins from their constituent amino acids, in accordance with the encoding gene DNA sequence.
Proteomics An approach that seeks to identify and characterize complete sets of protein, and protein-protein interactions in a given species.
Protozoan (pl.: protozoa) A microscopic, single-cell organism.
Purine A double-ring, nitrogen-containing base present in nucleic acids. Adenine (A) and guanine (G) are the two purines normally present in DNA and RNA molecules.
Pyrimidine A single-ring, nitrogen-containing base present in nucleic acids. Cytosine (C) and thymine (T) are present in DNA, whereas uracil (U) replaces T in RNA. Thymine is a synonym for 5-methyluracil.
Qualitative trait A trait that shows discontinuous variation – i.e. individuals can be assigned to one of a small number of discrete classes.
Quantitative genetics The area of genetics concerned with the inheritance of quantitative traits that show continuous variation, as opposed to qualitative traits. Since many of the critical targets in both plant and animal breeding are of this type, most practical improvement programs involve the application of quantitative genetics.
Quantitative structure-activity relationship (Abbreviation QSAR). A computer modelling technique that enables the prediction of the likely activity of a molecule before it is synthesized. QSAR analysis relies on recognizing associations of molecular structures and activity from historical data.
Quantitative trait A measurable trait that shows continuous variation (e.g. height, weight, colour intensity, etc.) – i.e. the population cannot be classified into a few discrete classes.