Glossary

Many of these terms have more general definitions as well. Those given here are specific to their application in cell culture and fermentation.

absorption Removing a particular antibody or antigen from a sample (from serum, for example) by adding the corresponding antigen or antibody.

adsorption Nonspecific adherence of substances in solution or suspension to cells or other particulate matter.

adventitious agents Acquired, sporadic, accidental contaminants.

aerobe An aerobic organism is one that grows in the presence of oxygen. A strict aerobe grows only under such a condition.

antigen An agent, often a large molecule, that stimulates production of an antibody that will react specifically with it.

bacteriophage A virus that infects bacteria, sometimes used as a vector.

base pair Two bases on different strands of nucleic acid that join together. In DNA, cytosine (C) always pairs with guanine (G) and adenine (A) always links to thymine (T). In RNA molecules, adenine joins to uracil (U).

bioactivity A protein's ability to function correctly after it has been delivered to the active site of the body (in vivo).

bioavailability Measure of the true rate and the total amount of drug that reaches the target tissue after administration.

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.

cloning vectors Methods of transferring desired genes to organisms that will be used to express them. Cloning vectors are used to make recombinant organisms.

cytokine A protein that acts as a chemical messenger to stimulate cell migration, usually toward where the protein was released. Interleukins, lymphokines, and interferons are the most common.

cytopathic Damaging to cells, causing them to exhibit signs of disease.

DNA fingerprinting Sequences of nucleic acids in specific areas on a DNA molecule are polymorphic, meaning that genes in those locations may differ from person to person. DNA fragments can be cut from those sequences using restriction enzymes.

DNA vaccine A nucleic acid vaccine: Genes coding for specific antigenic proteins are injected to produce those antigens and trigger an immune response.

endonuclease A restriction enzyme that breaks up nucleic acid molecules at specific sites along their length. Such enzymes are naturally produced by microorganisms as a defense against foreign nucleic acids.

endoplasmic reticulum A highly specialized and complex network of branching, interconnecting tubules (surrounded by membranes) found in the cytoplasm of most animal and plant cells. The rough endoplasmic reticulum is where ribosomes make proteins. It appears "rough" because it is covered with ribosomes. The smooth endoplasmic reticulum is the site for synthesis and metabolism of lipids.

eukaryotes Complex organisms, often multicellular, whose cells contain nuclei.

express To translate a cell's genetic information, stored in its DNA (gene), into a specific protein.

expression system Organisms chosen to manufacture (by expression) a protein of interest through recombinant DNA technology.

expression vector A way of delivering foreign genes to a host, creating a recombinant organism that will express the desired protein.

fusion partner When making a small protein or peptide in E. coli, it is often necessary to produce the protein fused to a larger protein to get high levels of stable expression. The resulting fusion protein must be cleaved (chemically or enzymatically broken) to yield the desired protein or peptide.

genotype The genetic composition of an organism (including expressed and nonexpressed genes), which may not be readily apparent.

germ cell The "sex cells" in higher animals and plants that carry only half of the organism's genetic material and can combine to develop into new living things.

glycosylation Adding one or more carbohydrate molecules onto a protein afterit has been built by the ribosome; a posttranslational modification.

Golgi body A cell organelle consisting of stacked membranes where posttranslational modifications of proteins are performed; also called Golgi apparatus.

hybridoma An immortalized cell line (usually derived by fusing B-lymphocyte cells with myeloma tumor cells) that secretes desirable antibodies.

interferon A cytokine that inhibits virus reproduction. Interferons also affect growth and development (differentiation) in certain normal and tumor cells.

ligase An enzyme that causes fragments of DNA or RNA to link together; used with restriction enzymes to create recombinant DNA.

lymphocytes White blood cells that produce antibodies.

lysosomes Cell organelles containing enzymes, responsible for degrading proteins and other materials ingested by the cell.

MAb Monoclonal antibody: A highly specific, purified antibody that recognizes only a single antigen.

macrokinetics Movement of whole cells and their media within a bioreactor.

metabolites Chemical byproducts of metabolism, the chemical process of life.

microcarrier A microscopic particle (often, a 200-μm polymer bead) that supports cell attachment and growth in suspension culture.

microencapsulated Surrounded by a thin, protective layer of biodegradable substance referred to as a microsphere.

microinjection Manually using tiny needles to inject microscopic material (such as DNA) directly into cells or cell nuclei; computer screens provide a magnified view.

microkinetics Movement of chemicals into, out of, and within the cell.

mitochondria Animal-cell organelles that reproduce using their own DNA. They metabolize nutrients to provide the cell with energy and are believed to have once been symbiotic bacteria. Chloroplasts are their plant-cell equivalents.

mutagen An agent (chemicals, radiation) that causes mutations in DNA.

mycoplasma parasitic microorganisms that infect mammals, possessing some characteristics of both bacteria and viruses.

nucleic acids DNA or RNA: long, chainlike molecules composed of nucleotides.

nucleotides Molecules composed of a nitrogen-rich base, phosphoric acid, and a sugar. The bases can be adenine (A), cytosine (C), guanine (G), thymine (T), or uracil (U).

nucleus The largest organelle, a sphere that contains all the cell's genetic material and a nucleolus that builds ribosomes.

oncogene A gene that, when expressed as a protein, can lead cells to become cancerous, usually by removing the normal constraints on its growth.

organelle A structurally discrete component that performs a certain function inside a eukaryotic cell.

peptides Proteins consisting of fewer than 40 amino acids.

phenotype The part of an organism's genotype that is expressed, and thus is generally apparent by observation.

plasmid Hereditary material that is not part of a chromosome. Plasmids are circular and self-replicating and found in the cytoplasm of cells (naturally in bacteria and some yeasts). They can be used as vectors for introducing up to 10,000 base-pairs of foreign DNA into recipient cells. Also known as episomes.

polymerase An enzyme that catalyzes production of nucleic acid molecules.

posttranslational modifications Protein processing done by the Golgi bodies after proteins have been constructed by ribosomes.

prions Resembling viruses, these pathogens are composed only of protein, with no detectable nucleic acid.

prokaryotes Simple organisms with no cell nuclei and very few cell organelles.

proteolytic Capable of lysing (denaturing, or breaking down) proteins.

recombinant Containing genetic material from another organism. Genetically altered microorganisms are usually referred to as recombinant, whereas plants and animals so modified are called transgenic (see transgenics).

restriction enzyme An bacterial enzyme that cuts DNA molecules at the location of particular sequences of base pairs.

ribosome Cell organelles that translate RNA to build proteins.

serum The watery portion of an animal or plant fluid (such as blood) remaining after coagulation. When cheese is made, whey is the milk serum that's left.

somatic cell In higher organisms, a cell that (unlike germ cells) carries the full genetic make-up of an organism.

sparge To spray. A sparger is a component of a fermentor that sprays air into the broth.

supernatant Literally, material floating on the surface of a liquid mixture (often the liquid component that has the lowest density). In biotechnology, it generally refers to the liquid portion of a culture broth after the cells have been removed.

tissue culture Growing plant or animal tissues outside of the body, as in a nutrient medium in a laboratory; similar to cell culture, but cells are maintained in their structured, tissue form.

titer A measured sample. (To draw a measured, representative sample from a larger amount is to titrate.)

transgenics The alteration of plant or animal DNA so that it contains a gene from another organism. There are two types of cells in animals and plants, germ line cells (the sperm and egg in animals, pollen and ovule in plants) and somatic cells (all of the other cells). It is the germ-line DNA that is altered in transgenic animals and plants, so those alterations are passed on to offspring.

translation The process by which information transferred from DNA by RNA specifies the sequence of amino acids in a polypeptide (protein) chain.

TSE (Transmissable Spongiform Encephalopathy) A class of brain-wasting diseases caused by prions, including scrapie (sheep), Mad Cow Disease (cattle), chronic wasting disease (elk, deer) kuru (humans), and variant Creutzfeldt-Jakob Disease (vCJD, humans).

turbulent flow field The state that results from mixing the contents of a fermentor or bioreactor to provide oxygen to the cells. That must be balanced against the shear that causes cell damage and death.

vector The plasmid, virus, or other vehicle used to carry a DNA sequence into the cell of another species.

vessel jacket A method for controlling the temperature of liquid in a vessel. The vessel is surrounded by a double-walled jacket through which liquid or steam flows to cool (or heat) the vessel. Vessel jackets can cause uneven heating (hot or cold spots), shell-and-tube or plate-and-frame heat exchangers are more common in biopharmaceutical production systems.

viability Life and health, ability to grow and reproduce; a measure of the proportion of live cells in a population.

virus The simplest form of life: RNA or DNA wrapped in a shell of protein, sometimes with a means of injecting that genetic material into a host organism (infection). Viruses cannot reproduce on their own, but require the aid of a host.

viscosity Thickness of a liquid; determines its internal resistance to shear forces.

water-for-injection Very pure water suitable for medical uses.

yeast A single-celled fungus.