omega-6 fatty acids

Fatty acids which have the first unsaturated bond in the sixth position from the omega carbon.

operon

In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic messenger RNA is under the control of an operator region

opportunity costs

The economic outcome of giving up an opportunity, often associated with investments.

organelles

A cell structure which has specific function.

organic production

A concept and practice of agricultural production that focuses on production without the use of synthetic inputs and does not allow the use of transgenic organisms.

organic foods

Organic food is produced without: antibiotics; growth hormones; most conventional pesticides; petroleum- based fertilizers or sewage sludge-based fertilizers; bioengineering; or ionizing radiation. USDA certification is required before a product can be labeled "organic". Companies, including restaurants, that handle or process organic food must be certified also

organic soils

A soil that contains a high percentage (greater than 20 or 30 percent) of organic matter in the upper layers (where living roots are primarily found

origin of replication

A unique DNA sequence of a replicon at which DNA replication is initiated and proceeds bidirectionally or unidirectionally. It contains the sites where the first separation of the complementary strands occurs, a primer RNA is synthesized, and the switch from primer RNA to DNA synthesis takes place.

ornamental trees

A tree cultivated for its beauty rather than for use. It is usually a small flowering tree used for understory or massed in the open for color and texture.

osmotic pressure

The pressure required to prevent osmosis through a semipermeable membrane separating two solutions of differing solute concentions

outcrossing

Mating individuals that belong to different strains or families within the same breed or variety

oxidative metabolism

Life or metabolic reactions occurring in an environment containing oxygen.

oxidative phosphorylation

The biochemical process in which ATP is synthesized from ADP and inorganic phosphate in cell metabolism.

phagocytosis

The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (phagocytes).

phenotype

The outward appearance of the individual. It is the product of interactions between genes, and between the genotype and the environment

phloem

The tissues of the inner bark, characterized by the presence of sieve tubes and serving for the transport of elaborate foodstuffs.

photoperiodism

The physiological and behavioral response of an organism to the relative duration of light and darkness.

photorespiration

The consumption of oxygen, due to the oxidation of carbohydrates, and the output of carbon dioxide during photosynthesis.

photosensitivity

Characterized by sensitivity or responsiveness to light or other radiant energy.

photosynthates

The resulting chemical products of photosynthesis.