Rational drug design: using the known three-dimensional structure of a molecule, usually a protein, to design a drug that will bind it.

Recombinant DNA: the DNA formed by combining segments of DNA from different sources.

Restriction enzyme: a protein that cuts DNA molecules at specific sites, dictated by the nucleotide sequence.

Retrovirus: a type of virus that reproduces by converting RNA into DNA.

Single Nucleotide Polymorphism (SNP): a single base difference in the sequence of a gene which alters the structure and function of the gene product.

RNA (ribonucleic acid): a nucleic acid, similar to DNA, that has roles in gene expression.

RNA interference: using antisense techniques to selectively inhibit expression of a gene.

Stem cell: an undifferentiated cell that can multiply and become any sort of cell in the body.

Tissue engineering: the production of natural or synthetic organs and tissues that can be implanted as fully functional units or may develop to perform necessary functions following implantation

Transcription: the synthesis of an mRNA molecule as a copy of a gene. In gene expression, transcription precedes translation.

Translation: the synthesis of a protein based on the nucleotide sequence of an mRNA molecule, which corresponds to the sequence of a gene.

Transgenic: an organism with one or more genes that have been transferred to it from another organism.

Vaccine: a preparation of either whole disease-causing organisms (killed or weakened) or parts of such organisms, used to confer immunity against the disease that the organisms cause. Vaccine preparations can be natural, synthetic, or derived by recombinant DNA technology.

X-ray crystallography: an essential technique for determining the three-dimensional structure of biological molecules.

Xenotransplantation: transplanting a foreign tissue into another species.