Active site: The portion of a protein where a ligand binds

addition polymerization: a chemical reaction in which simple molecules are linked together to form long chain molecules.

Adenine is one of the four bases in DNA that make up the letters ATGC, adenine is the "A". The others are guanine, cytosine, and thymine. Adenine always pairs with thymine.

Algorithm A method of solving a problem, involving a finite series of steps. A fixed procedure embodied in a computer program

Alignment The process of lining up two or more sequences to achieve maximal levels of identity (and conservation, in the case of amino acid sequences) for the purpose of assessing the degree of similarity and the possibility of homology.

alignment scores. The raw score S for an alignment is calculated by summing the scores for each aligned position and the scores for gaps. In this figure, a DNA alignment is shown.

Allosteric: Under certain conditions, a protein may have a stable alternate conformation, or shape, that enables it to carry out a different biological function. Proteins that exhibit this characteristic are called allosteric. Allosteric proteins can change their shape and function depending on the environmental conditions in which they are found.

Alpha carbon The carbon in an amino acid which has the functional groups attached. The term is usually used when talking about protein sequence or structure as a protein is composed of a sequence of amino acids.

Alpha helix A helical portion of a protein structure. The hydrogen bonds form between neighbouring amino acids or such of the vicinity, so that the chain winds up to a helix. Stable, however, does not mean rigid. Due to the thermal movement all atoms within a molecule move against one another

Picture below: Demonstrated on the antlers of a kudu (from C. DARWIN:The descent of man, 1871)

Images courtesy of Peter v. Sengbusch

Amino acid The basic building block of proteins. A molecule with an amine and a carboxylic acid substituent on a single carbon.

amorphous: non-crystalline polymer or non-crystalline areas in a polymer.

Antibody is a blood protein that is produced in response to and counteracts an antigen. Antibodies are produced in response to disease and help the body fight against the particular disease. In this way, antibodies help the body develop an immunity to disease.

asynchronous operation: a type of operation between two computers. A computer sends a message to the other and does not require a reply in order for it (the sender) to continue.

Authentication: the act of ensuring the validity of data transferred over the network or logged-in users.

Autosome Any chromosome other than a sex chromosome. Humans have 22 pairs of autosomes.

Web Author: Tug Sezen