Pleiotropic

A gene having multiple phenotypic traits

Polymorphism

The presence of two or more alleles of a particular gene within a population of organisms.

Prokaryotic

Cells in which the nuclear region is not separated from the cytoplasm by a membrane.

Pronucleus

A haploid nucleus formed by either the sperm head or the egg nucleus after fertilization but before the nuclei fuse to form the diploid zygotic nucleus.

Proteomics

Analysis of an organism’s protein composition and function.


Reference dose (RfD)

An estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime.

Reference concentration (RfC)

An estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious noncancer effects during a lifetime.

Relative risk

The ratio of incidence or risk among exposed individuals to incidence or risk among nonexposed individuals.

Restriction fragment length polymorphism (RFLP)

Variations in DNA sequence that are indicated by the presence or absence of particular restriction sites in the DNA.

Restriction sites

Specific, short DNA sequences that are recognized by restriction enzymes that cleave the duplex DNA.

Reverse genetics

An approach to identify the function of a particular gene starting with a cloned copy of that gene.

Ribonucleic acid (RNA)

A complex macromolecule composed of adenine, cytosine, guanine, and uracil that is found in cellular organisms. RNA can serve several functions, including encoding the genetic information copied from DNA in the form of a sequence of bases that specifies a sequence of amino acids.



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