cell lines When cells from the first culture (taken from the organism) are used to make subsequent cultures, a cell line is established. Thanks to genetic or other manipulations, immortal cell lines can replicate indefinitely.

cellulose A fibrous polysaccharide material, the main ingredient of plant cell walls.

centrifugation Spinning samples at high speeds, using centrifugal force (up to 500,000 times the force of gravity) to separate substances with very small differences in density or weight.

certificate of analysis (COA) A batch-specific document that is used to list test methods and results, including applicable specifications, and a final batch disposition

CFR Code of Federal Regulations; the U.S. regulations that directly apply to biopharmaceutical development are in Title 21 parts 58, 210, 211, and 600. Parts 50, 56, and 312 apply to clinical trials.

cfu Colony forming units; a measurement of the number of microorganisms present derived from the number of colonies that form in a test culture.

cGMP Current good manufacturing practice; see GMP.

change control A system by which changes to facilities, equipment, and processes are documented and approved. The change control system ensures that changes are evaluated and approved prior to implementation to maintain the facilities, equipment, and processes in a validated state.

chaotropic Disrupting the structure of water, macromolecules, or living systems to promote activities that would have been inhibited by the water, molecules, or systems.

characterization Precisely deciphering and describing an entity's properties (physical and chemical properties in the case of a molecular entity; genetic and stability properties in the case of a cell line).

charge The electrical state of an atom or molecule, whether positive, negative, or neutral, according to the difference of protons (positively charged) to electrons (negatively charged).

chelation The binding or holding of a metal ion (such as copper, zinc, cadmium, nickel, or cobalt) by another molecule or by another part of the same molecule; used in a form of affinity chromatography called "metal chelate chromatography."

chelator A molecule used to bind a metal ion with more than one organic group to form a highly stable structure.

chemical synthesis Nonbiotech method of manufacturing chemicals, including drugs.

chemostat A growth chamber that keeps a bacterial culture at a specific volume and rate of growth by limiting nutrient medium and removing spent culture.

CIP (or SIP) systems are preferable when at all possible. The more complex the equipment, the more difficult it is to take apart and clean well.

chirality The condition of being chiral, that is, a molecule in a configuration that is symmetrical with its mirror image; a right-handed chiral molecule rotates polarized light rightward, a left-handed chiral molecule rotates polarized light leftward.

CHO cells Chinese hamster ovary cells; in cell culture, the cells of a female hamster's reproductive organs, which historically have proven to be the basis for good expression systems in analytical studies and for producing pharmaceutical proteins.