A gene that upon transfection enables a primary cell to grow indefinitely in culture. (See Oncogene.)

Refers to performing assays or manipulations with intact tissues.

Refers to biological processes that take place within a living organism or cell.

A condition where a heterozygous off- spring has a phenotype that is distinctly different from, and intermediate to, the parental phenotypes. See Heterozygote, Phenotype.

The mRNA sequence AUG, coding for methionine, which initiates translation of mRNA.

A membrane-anchored phospholipid that transduces hormonal signals by stimulating the release of any of several chemical messengers. (See Phospholipid.)

Changes in the base sequence of a DNA molecule resulting from the random integration of DNA from another source. See DNA, Mutation.

A peptide hormone secreted by the islets of Langerhans of the pancreas that regulates the level of sugar in the blood.

A family of small proteins that stimulate viral resistance in cells.

DNA sequences located between genes that comprise a large percentage of the human genome with no known function.

Backcrossing of hybrids of two plant populations to introduce new genes into a wild population.

A noncoding DNA sequence within a gene that is initially transcribed into messenger RNA but is later snipped out. See Coding, DNA, Messenger RNA, Transcription.

Ability of a plant to spread beyond its introduction site and become established in new locations where it may provide a deliterious effect on organisms already existing there.

A charged particle.

One of two or more forms of an element that have the same number of protons (atomic number) but differing numbers of neutrons (mass numbers). Radioactive isotopes are commonly used to make DNA probes and metabolic tracers.