Genomics glossary

Cell —The basic subunit of any living organism; the simplest unit that can exist as an independent living system.

Chromosome —A structure of DNA and protein found in the cell nucleus. Each chromosome contains hundreds or thousands of the genes that form our hereditary blueprint. Humans have 23 pairs of chromosomes (each parent contributes one chromosome in each pair), containing a total of 50,000 to 100,000 genes.

DNA (deoxyribonucleic acid) —The genetic material of living organisms; the substance of heredity. It is a large, double-stranded, helical molecule that contains genetic instructions for growth, development and replication.

DNA microarray —A wafer similar to a computer chip that can be used to swiftly screen for the presence of particular genetic sequences.

ELSI —Acronym for the ethical, legal and social implications of the Human Genome Project.

Gene —A sequence of DNA that represents a fundamental unit of heredity. Most genes encode proteins, but some code for RNA molecules.

Gene Expression —The process by which the information encoded in a gene is converted into protein or some form of RNA. The DNA sequence is first transcribed into RNA and then usually translated into protein.

Genotype —The genetic makeup—DNA sequence—of an individual at one or more places in the genome.

Gene Therapy —Treatment of a disease by introducing a new gene into a cell. The new gene may be used to replace a function that is missing because of a defective gene, to help protect normal cells from the effects of drugs (such as those used to treat cancer), or to protect cells from viruses, such as the AIDS virus.

Genetic disease —A disease caused by a genetic mutation that is either inherited or arises spontaneously.

Genome —The total genetic information of a particular organism. The normal human genome consists of three billion base pairs of DNA.

Genomics —The study of the structure and function of large numbers of genes simultaneously.

Medical Informatics —An emerging discipline that melds the data analysis tools of computing with medical information and the provision of health-care services.

Phenotype —The physical or biological characteristics of an organism arising from the interaction of its genotype and environmental factors.

Protein —A molecule composed of amino acids linked together in a particular order specified by a gene’s DNA sequence. Proteins perform a wide variety of functions including serving as enzymes, structural components or signaling molecules.

Proteomics —The study of the set of proteins produced (expressed) by an organism, tissue or cell, and the changes in protein expression patterns in different environments and conditions.

RNA (ribonucleic acid)—A single-stranded nucleic acid (similar to the double-stranded nucleic acid DNA) involved in protein synthesis.

Vector —A “carrier.” In gene therapy, for example, the method of carrying and inserting the desired gene into the target cell.