Science terms starting with P

1,062 terms

Primary Air The air that is supplied to the combustion chamber of a furnace.
Primary Ambient Air Quality Standards Air quality standards designed to protect human health.
primary antibody In an ELISA or other immunological assay, the antibody that binds to the target molecule.
Primary cell A cell or cell line taken directly from a living organism, which is not immortalized.
primary cell wall The cell wall layer formed during cell expansion. Plant cells possessing only primary walls may divide or undergo differentiation.
Primary Control Tide Station A tide station where continuous observations have been made for a minimum of 19 years.
primary culture A culture started from cells, tissues or organs taken directly from organisms. A primary culture may be regarded as such until it is sub-cultured for the…
Primary excavation Digging in undisturbed soil, as distinguished from rehandling stockpiles.
Primary germ layers See: germ layer.
primary growth 1. Apical meristem -derived growth; the tissues of a young plant. 2. Explant growth during the initial culture period.
primary immune response The immune response that occurs during the first encounter of a mammal with a given antigen.
primary immunodeficiency A group of rare inherited disorders of the immune system, including adenosine deaminase deficiency, severe combined immunodeficiency (SCID), and…
primary meristem Meristem of the shoot or root tip giving rise to the primary plant body.
Primary oil recovery Pumping out the crude oil that flows by gravity into the bottom of an oil well. See enhanced oil recovery, secondary oil recovery.
Primary Pollutant Substances that are pollutants immediately on entering the atmosphere. Compare secondary pollutant.
Primary production Creation of organic matter by photosynthesis.
primary structure The linear sequence of residues making up a polymer such as a nucleic acid, polysaccharide or protein.
Primary Swell Direction Prevailing direction of swell propagation.
primary tissue A tissue that has differentiated from a primary meristem.
primary transcript The RNA molecule produced by transcription prior to any post-transcriptional modifications; also called a pre-mRNA in eukaryotes.
Prime See Subprime
Prime Mover Any machine capable of producing power to do work.
Primer A short DNA or RNA fragment annealed to single-stranded DNA, from which DNA polymerase extends a new DNA strand to produce a duplex molecule.
primer walking A method for sequencing long (>1 kbp) cloned pieces of DNA. The initial sequencing reaction reveals the sequence of the first few hundred nucleotides of…
Primitive streak The initial band of cells from which the embryo begins to develop. The primitive streak establishes and reveals the embryo's head-tail and left-right…
Primordial germ cell A gamete, that is, a sperm or egg, OR a primordial cell that can mature into a sperm or egg.
Primordial Nucleosynthesis Building of the atomic elements in the early universe when nuclei fused with one another. Most of the helium in the universe was created by this process.
primordium A group of cells which gives rise to an organ.
primosome A protein -replication complex that catalyses the initiation of synthesis of Okazaki fragments during discontinuous replication of DNA.
PRIN Principal
Principal organizations Federal, State, and local agencies or departments or executive offices having major or lead roles in emergency planning and preparedness for emergency…
Prion See Proteinaceous infectious particle.
Prion-related protein (PrP) A normal protein, expressed in the nervous system of animals, whose structure when altered (by interaction with altered copies of itself) is the cause of…
Prior appropriation A doctrine of water law that allocates the right to use water on a first-come first-serve basis.
Prior Appropriation Doctrine A system for allocating water rights used in the western United States under which the first person (or entity) to divert water from a source has a…
Privacy In genetics, the right of people to restrict access to their genetic information.
Private sector Industry, volunteer, quasi-governmental, etc., having a role in emergency planning and preparedness.
pro-embryo A group of cells arising from the division of the fertilized egg cell or somatic embryo before those cells which are to become the embryo are recognizable.
pro-meristem The embryonic meristem that is the source of organ initials or foundation cells.
pro-nuclear micro-injection An early, low success-rate method to achieve transgenesis in animals, involving the micro-injection of many gene copies into one of the two pro-nuclei of…
pro-nucleus Either one of the two haploid gamete nuclei, just prior to their fusion in the fertilized egg.
pro-phage The genome of a bacteriophage integrated into the chromosome of a lysogenic bacterial cell, and replicated along with its host chromosome.
pro-toxin A latent, non-active precursor form of a toxin.
Probabilistic Quantitative Precipitation Forecast (PQPF) A form of QPF (see below) that includes an assigned probability of occurrence for each numerical value in the forecast product.
Probability The chance that an event occurs. It is usually expressed as a percent. Zero percent denotes impossibility, while 100% denotes certainty.
Probability Forecast A forecast of the probability that one or more of a mutually exclusive set of weather conditions will occur.
Probability of failure Likelihood that, given the loading event and failure mode, the structure responds with the necessary adverse occurrences to ultimately result in…
Probability of Hail (Abbrev. POH) - a product from the NEXRAD hail detection algorithm that estimates the likelihood that hail is present in a storm.
Probability of load Likelihood that a certain loading event (static, seismic, hydrologic, other) occurs at a structure site.
Probability of Precipitation (Abbrev. PoP)- The probability that precipitation will be reported at a certain location during a specified period of time.
Probability of Thunderstorms The probability based on climatology that a thunderstorm will be reported at that location during a specified period of time.
Probability of Tropical Cyclone Conditio The probability, in percent, that the cyclone center will pass within 50 miles to the right or 75 miles to the left of the listed location within the…
Probable maximum flood (PMF) (maximum probable flood, MPF) The largest flood that may reasonably be expected to occur at a given point on a stream from the most severe combination of critical meteorologic and…
Probable maximum precipitation (PMP) Theoretically, the greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular…
proband The individual in a family in whom an inherited trait is first identified.
Probe A sequence of DNA or RNA, labeled or marked with a radioactive isotope, used to detect the presence of complementary nucleotide sequences. See Nucleotide.
Problem Identification Form (PIF) Used to identify and document problems with ARM systems, physical infrastructure, or instruments.
procambium A primary meristem that gives rise to primary vascular tissues and, in most woody plants, to the vascular cambium.
procaryote See: prokaryote, prokaryotic.
procaryotic (adj.) See: procaryote.
process development unit An experimental facility that establishes proof of concept, preliminary process economics, and engineering feasibility for a pilot or demonstration plant.
Process Heat Thermal energy that is used in agricultural and industrial operations.
processed pseudo-gene A copy of a functional gene which has no promoter, no introns and which, consequently, is not itself transcribed.
Producer Gas Low or medium Btu content gas, composed mainly of carbon monoxide, nitrogen(2), and hydrogen(2) made by the gasification of wood or coal.
Product Resolution The smallest spatial increment or data element that is distinguishable in a given Doppler radar product.
Production The process of delivering to another party, or making available for that partys review, documents deemed responsive to a discovery request.
production environment All input-output relationships, over time, at a particular location. The relationships include biological, climatic, economic, social, cultural and…
production traits Characteristics of animals, such as the quantity or quality of the milk, meat, fibre, eggs, work, etc.
Productive machine hours That portion of scheduled operating hours during which a machine performs its designated functions, excluding time to transport the machine and…
productivity The amount of economically significant product generated within a given period of time from a specified quantity of resource.
Products of Combustion The elements and compounds that result from the combustion of a fuel.
profile A sectional view showing grades and distances, usually taken along the centerline.
Profiler An instrument designed to measure horizontal winds directly above its location, and thus measure the vertical wind profile.
Profundal Deepest part of the ocean or lake where light does not penetrate. This layer usually has fewer nutrients, more silt, and fewer organisms than the surface.
PROG Forecast (prognostication)
Progenitor cell A progenitor cell, often confused with stem cell, is an early descendant of a stem cell that can only differentiate, but it cannot renew itself anymore.
progeny Offspring; the product of reproduction or replication.
progeny testing With respect to discrete loci, the inference of the allelic state of an individual from the pattern of segregation among its offspring.
progesterone (proh-JES-tuh-RONE) A type of hormone made by the body that plays a role in the menstrual cycle and pregnancy.
PROGGED Forecasted
Prognostic Discussion This Hydrometeorological Prediction Center (HPC) discussion may include analysis of numerical and statistical models, meteorological circulation patterns…
Programmable Thermostat A type of thermostat that allows the user to program into the devices' memory a pre-set schedule of times (when certain temperatures occur) to turn on…
Programmatic environmental impact statement (PEIS) An environmental impact statement that addresses a proposal to implement a specific policy, to adopt a plan for a group of related actions, or to…
programmed cell death A type of cell death in which a series of molecular steps in a cell leads to its death.
Programmed timber harvest A timber harvest scheduled by a management plan to occur at a certain rate.
Progressive Derecho Derecho characterized by a short curved squall line oriented nearly perpendicular to the mean wind direction with a bulge in the general direction of the…
Project A single financial entity which can be composed of several units or divisions, integrated projects, or participating projects.
Project financing A form of asset-based financing in which a firm finances a discrete set of assets (the project) on a stand-alone basis.
Project Hazardous Waste Coordinator (PHWC) Individual designated by the Area Manager to coordinate records and maintain proper management of hazardous wastes on each project; acts as primary…
Project-use energy This is intended to cover primarily power and energy used for project operations such as pumping or other miscellaneous uses.
Project-use power Power for main conveyance pumping, designated drainage pumping and other designated miscellaneous electric loads directly associated with the operation of…
Projected Area The net south-facing glazing area projected on a vertical plane. Also, the solid area covered at any instant by a wind turbine's blades from the…
Projectile point Any sharp tip of an arrow, spear, or dart.
Prokaryote A bacterial cell lacking a true nucleus; its DNA is usually in one long strand. See Eukaryote.
prolactin (proh-LAK-tin) A hormone that is made by the pituitary gland (a pea-sized organ in the center of the brain).
Proliferation Increase by frequent and repeated reproduction; growth by cell division.
Prominence A structure in the corona consisting of cool plasma supported by magnetic fields.
Prominences A structure in the Sun’s corona consisting of cool plasma supported by magnetic fields.
Promoter Any person who, directly or indirectly, organizes or assists in the organization of a tax shelter or who participates in the sale of any interests in a…
promoter sequence See: promoter (1).