phagemidsCloning vectors that contain components derived from both phage and plasmid DNA.
phagocytesImmune system cells that ingest and destroy viruses, bacteria, fungi and other foreign substances or cells.
phagocytosis(FA-goh-sy-TOH-sis) The process by which a phagocyte (a type of white blood cell) surrounds and destroys foreign substances (such as bacteria) and removes…
pharmacokinetics(FAR-muh-koh-kih-NEH-tix) The activity of drugs in the body over a period of time, including the processes by which drugs are absorbed, distributed in the…
Phase ChangeA method of storing information on rewritable optical discs.
phase stateThe coupling or repulsion of two linked genes.
PhenocopyAn environmentally induced, non hereditary variation in an organism, resembling a genetically determined trait.
phenolic oxidationCommon aspect of the wound response in plants. Phenolic oxidation is often indicated by blackening of tissue and it may be a precursor to growth…
phenolicsCompounds with hydroxyl group(s) attached to the benzene ring, forming esters, ethers and salts.
PhenotypeThe observable characteristics of an organism, the expression of gene alleles (genotype) as an observable physical or biochemical trait. See Genotype.
PheromoneA hormone-like substance that is secreted into the environment.
phloemSpecialized vascular plant tissue for the transport of assimilates (generally sugars) from the point of synthesis (in the leaf) to other parts of the…
PhosphataseAn enzyme that hydrolyzes esters of phosphoric acid, removing a phosphate group.
photosynthetic photon flux(Abbreviation: PPF). A measure of the intensity of light utilized by plants for photosynthetic activity.
photosynthetically active radiation(Abbreviation: PAR). The part of the radiant energy that is capturable by natural photosynthetic systems (approximately equivalent to the natural light…
phototropismThe tendency of plants to direct shoot growth towards the source of light.
phylogenyThe deduced evolutionary history of related organisms.
Physical mapA map showing physical locations on a DNA molecule, such as restriction sites, and sequence-tagged sites. (See Mapping.)
phytochemical(FY-toh-KEH-mih-kuhl) A substance found in plants. Some phytochemicals may reduce the risk of cancer.
phytochromeA pigment, found in the cytoplasm of green plants, which can exist in two forms Pr (biologically inactive) and Pfr (biologically active).
phytohormoneA substance that stimulates growth or other processes in plants. Major species are auxin s, abscisic acid, cytokinin s, gibberellin s and ethylene.
phytoremediationThe use of plants actively to remove contaminants or pollutants from either soils (e.g. polluted fields) or water resources (e.g. polluted lakes).
phytostatApparatus designed for the semi-continuous chemostatic culture of plant cells.
phytosterolA plant-based compound that can compete with dietary cholesterol to be absorbed by the intestines, resulting in lower blood cholesterol levels.
pigmentA substance that gives color to tissue. Pigments are responsible for the color of skin, eyes, and hair.
pinocytosisThe engulfing of a minute droplet of liquid by a living cell.
pipetteWidely used device for accurate dispensing of small volumes of liquids.
pistilCentral organ of the flower, typically consisting of ovary, style and stigma. Usually referred to as the female part of a perfect flower.
plant breeders' rights(Abbreviation: PBR). Legal protection of a new plant variety granted to the breeder or his successor in title.
plant cell immobilizationEntrapment of plant cells in gel matrices so that they are protected from physical damage.
plant genetic resources(Abbreviation: PGR). The reproductive or vegetative propagating material of: 1.
plant growth regulatorAn organic compound, either natural or synthetic, and other than a nutrient, that modifies or controls one or more specific physiological processes within…
Plant-incorporated protectantsFormerly referred to as plant-pesticides, plant-incorporated protectants (PIPs) are substances that act like pesticides produced and used by a plant to…
plantibodyAn antibody expressed transgenically in an engineered plant.
plantletA small rooted shoot regenerated from cell culture following embryogenesis or organogenesis.
plaqueA film of mucus that traps bacteria on the surface of the teeth. Plaque can be removed with daily brushing and flossing of teeth.
Plasma(PLAZ-muh) The clear, yellowish, fluid part of the blood that carries the blood cells. The proteins that form blood clots are in plasma.
plasma cellsAntibody-producing white blood cells derived from B lymphocyte s.
plasma membrane(PLAZ-muh MEM-brayn) The outer membrane of a cell.
plasmalemmaThe lipid bilayer and associated proteins and other molecules that surrounding the protoplast, within the cell wall.
PlasmidAn circular self-replicating non-chromosomal DNA molecule found in many bacteria, capable of transfer between bacterial cells of the same species, and…
Plasmid (p)A circular DNA molecule, capable of autonomous replication, which typically carries one or more genes encoding antibiotic resistance proteins.
plasmodesma(pl.: plasmodesmata) Fine protoplasmic thread that connects adjacent plant cells by passing through the plant cell wall.
plasmolysisShrinkage of protoplasm caused by removal of water from a cell through osmosis when surrounded by a hypertonic solution.
plastidA general term for a number of plant s which carry non-nuclear DNA. Includes the pigment -carrying bodies: 1. chloroplasts in leaves, 2.
plastoquinoneOne of a group of compounds involved in the transport of electrons as part of the process of photosynthesis.
plate1. Verb: to distribute a thin film of micro-organisms or plant cells onto a solid medium. 2. Noun: refers to the two segments of a Petri dish or similar.
Point mutationA change in a single base pair of a DNA sequence in a gene. (See Mutation.)
polar bodiesIn female animals, the products of a meiotic division that do not develop into a functional ovum.
polar mutationA mutation that influences the functioning of genes that are downstream from the site of mutagenesis but are in the same transcription unit.
polar nucleiTwo centrally located nuclei in the embryo sac that unite with a second sperm cell in a triple fusion.
polar transportA directed movement within plants of compounds (usually endogenous plant growth regulators) mostly in one direction; polar transport overcomes the…
PolarityThe observed differentiation of an organism, tissue or cell into parts having opposed or contrasted properties or form.
pole cellsA group of cells in the posterior of Drosophila embryos that are precursors to the adult germ line.
pollen cultureThe in vitro culture and germination of pollen grains to generate haploid plants. See: anther culture;.
pollen grainThe mature microspore, produced in the pollen sac of angiosperms or the microsporangium of gymnosperms.
pollinationTransfer of pollen from anther to stigma in the process of fertilization in angiosperms; transfer of pollen from male to female cone in the process of…