Apoptosome A complex that comprises Apaf-1, cytochrome c released from the mitochondria, deoxyadenosine triphosphate (dATP) and procaspase-9 whose assembly is central to the activation of procaspase-9 and downstream apoptotic cell death.
Appendix A collection of immune system tissue near the junction of the small and large intestines, part of the MALT.
Applet A small application program that can be executed by selecting a link or by automatic executing when a HTML document is loaded by a browser. Applets are usually written in java permitting them to run on different operating systems and use GUl to provide input/output with the user.
Application Software installed for a specific purpose on a computer (such as word processing). This is distinct from the operating system or system software.

Aquaculture Growing of water plants and animals in large volumes of water (usually fresh water), rather than harvesting them from rivers or seas. The animals are provided clean, well-aerated water, food such as krill or powdered synthetic food, and food additives, such as astaxanthins. Aquaculture is regarded as a part of biotechnology because it has commercial value. It is used for the mass-production of macro-and micro-algae for chemicals, vitamins and pigments.
Aqueous Pertaining to water.
Aqueous two-phase separation A technique to partition proteins during purification using polyethylene glycol and dextran (or phosphate).

Arbitrarily primed PCR PCR using random primers, such as in RAPD analysis.
ARC AIDS-related complex. A series of symptoms related to HIV infection including malaise, night sweats, dementia, wasting, opportunistic diseases such as Kaposi’s sarcoma, pneumonia  and retinitis.
Archaebacteria A group of bacteria that are very different from, and more primitive than other living bacteria, believed to have evolved from Eubacteria and from the eukaryotes. They constitute a third group of organisms and include methanogens, which produce methane from carbon dioxide and hydrogen and halophiles that live in high-salt environments.
Archive A collection of files that may be stored in a single compressed file in a special archive format. Also see zip, gz.
ARF protein Monomeric GTPase that regulate COPI coat assembly and clathrin coat assembly at Golgi membranes.