oestrous cycleThe cycle of reproductive activity shown by most sexually mature non-pregnant female mammals. AlteRNA tive spelling: estrous.
oestrusIn female mammals, the period of sexual excitement and acceptance of the male. Synonyms: rut, heat. AlteRNA tive spelling: estrus (adj.: estrous).
offsetYou offset an options or futures position by taking a second position in a contract with identical terms, buying if you sold initially or selling if you…
offshootShort, usually horizontal, stem produced near the crown of a plant.
offspringNew individuals resulting from sexual or asexual reproduction. Synonym: progeny.
Okazaki fragmentReplicated DNA fragments formed on the lagging strand in DNA synthesis from a double-stranded template.
OLAAbbreviation for oligonucleotide ligation assay.
oligomerA molecule formed by the covalent joining of a small (undefined) number of monomers . See: polymer.
OligonucleotideA DNA polymer composed of only a few nucleotides. (See Nucleotide.)
oligonucleotide ligation assay(Abbreviation: OLA). A diagnostic technique for determining the presence or absence of a single nucleotide polymorphism within a sequence, often…
open continuous cultureA continuous culture system, in which inflow of fresh medium is balanced by outflow of a corresponding volume of spent medium plus cells.
Open pollinationPollination by wind, insects, or other natural mechanisms.
Open reading frameA long DNA sequence that is unin- terrupted by a stop codon and encodes part or all of a protein. (See Reading frame.)
operational definitionAn operation or procedure that can be carried out to define or delimit something.
operatorA prokaryotic regulatory element that interacts with a repressor to control the transcription of adjacent structural genes.
OperonA functionally integrated genetic unit for the control of gene expression in bacteria.
OPINEThe condensation product of an amino acid with either a keto-acid or a sugar, produced by the plant host as a result of Agrobacterium infection, and used…
organogenesisThe initiation of adventitious or de novo shoots or roots from callus, meristem or suspension cultures. See: micropropagation; regeneration.
organoidAn organ-like structure produced in culture.
organolepticHaving an effect on one of the organs of sense, such as taste or smell.
orphan geneA gene or DNA sequence whose function is not known.
orphan receptorA receptor for which a cellular function or ligand has yet to be identified.
ortetThe plant from which a clone is obtained. Synonym: donor plant.
orthologousHomologous genes/gene products that have evolved divergently between species; many rice genes have orthologues in other cereal genomes, because of the…
OSHASee Occupational Safety and Health Administration.
osmosisDiffusion of water across a semi-permeable membrane from zones of low solute concentration to zones of higher solute concentration.
osmotic potentialChange in the energy state of solvent brought about by dissolving a substance in the solvent - water in the biological sciences.
osmoticumA chemical agent (e.g. polyethylene glycol, mannitol, glucose or sucrose) employed to maintain the osmotic potential of a nutrient medium equivalent to…
outbreedingA mating system characterized by the inter-breeding of genetically unrelated or dissimilar individuals.
OutflowThe volume of growing cells that is removed from a bioreactor during a continuous fermentation process.
ovary(OH-vuh-ree) One of a pair of female reproductive glands in which the ova, or eggs, are formed.
overdominanceWhere heterozygote performance is superior to that of either parental genotype.
ovum pickup(Abbreviation: OPU). The non-surgical collection of ova from a female.
oxidative phosphorylationThe enzymatic addition of a phosphate to ADP to make ATP, coupled to electron transport from a substrate to molecular oxygen.
oxygen-electrode-based sensorSensor in which an oxygen electrode, which measures the amount of oxygen in a solution, is coated with a biological material such as an enzyme which…