Enzyme: A functional protein that catalyzes (speeds up) a chemical reaction. Enzymes control the rate of naturally occurring metabolic processes such as those necessary for growth and reproduction.

Escherichia coli (E. coli): a common gut bacteria that is a workhorse and model organism for molecular biology.

Excipient: an inactive ingredient (there are no absolutely inert excipients) added to a drug to give it a pill form or otherwise aid in delivery.

Expression: a highly specific process in which a gene is switched on at a certain time and begins production of its protein, resulting in the manifestation of a characteristic that is specified by a gene. Genetic predispositions to disease can occur, for example, if a person carries the gene for a disease but it is not expressed.

False negative: an experimental outcome that incorrectly yields a negative result. False negatives can complicate disease diagnosis.

False positive: an experimental outcome that incorrectly yields a positive result. False positives can frustrate assessing the performance of lead compounds.

Functional genomics: the use of biological experiments and database searches to establish what each gene does, how it is regulated, and how it interacts with other genes.

Functional foods: foods containing compounds with beneficial health effects beyond those provided by the basic nutrients, minerals and vitamins.

Gene: the fundamental unit of heredity, a section of DNA which codes for a defined biochemical function. Some genes direct the synthesis of proteins, while others have regulatory functions.

Gene therapy: the replacement of a defective gene in a person or organism suffering from a genetic disease.

Genetic code: the language in which DNA’s instructions are written. The genetic code consists of triplets of nucleotides (codons), with each triplet corresponding to one amino acid in a protein structure or a signal to start or stop protein production.

Genetic disorder: a condition or mutation that results from one or more defective genes.

Genetic engineering: the manipulation of genes to create heritable changes in biological organisms and products that are useful to people, living things, or the environment.