Explanation: Unlike plant cells, primary mammalian cells do not normally form aggregates, but grow in the form of monolayers on support surfaces such as glass surfaces of flasks. Using the proteolytic enzyme trypsin, individual cells in a tissue can be separated to form single-cell cultures.

Explanation: The “T” referred to the total surface area of the flask that was available for cell growth: thus a T-25 flask had a 25cm2 growth area. By the 1960s, straight neck T-flasks was available molded from polystyrene that was treated to enhance cell attachment.

Explanation: Flasks are divided into 6 types, depending on the culture scale and the cap type. Cell growth area for T25, T75 and T175 are 25 cm², 75 cm², and 175 cm², respectively. Each flask can be provided with plug or filter caps.

Explanation: The typical concentration of use of EDTA is less than 2%, with the other salts in current use at even lower concentrations. The lowest dose reported to cause a toxic effect in animals was 750 mg/kg/day. These chelating agents are cytotoxic and weakly genotoxic, but not carcinogenic.

Explanation: Cells that can be propagated indefinitely are called continuous, immortal, or transformed cell lines. Cancer cells are naturally immortal. All cancerous cell lines are transformed, although it is not clear whether all transformed cell lines are cancerous.

Explanation: One particular characteristic is contact inhibition. In two-dimensional culture on a surface nontransformed cells form only a monolayer, as cell division is inhibited when a cell’s surface is in contact with other cells. Transformed cells do not “sense” the presence of other cells and keep on dividing to form multilayer structures.

Explanation: The baculovirus that infects insect cells is an ideal vector for genetic engineering, because it is nonpathogenic to humans and has a very strong promoter that encodes for a protein that is not essential for virus production in cell culture. The insertion of a gene under the control of this promoter can lead to high expression levels (40% of the total protein as the target protein).

Explanation: Hybridoma cells are obtained by fusing lymphocytes (normal blood cells that make antibodies) with myeloma (cancer) cells. Lymphocytes producing antibodies grow slowly and are mortal. After fusion with myeloma cells, hybridomas become immortal, can reproduce indefinitely, and produce antibodies. Using hybridoma cells, highly specific, monoclonal (originating from one cell) antibodies can be produced against specific antigens.

Explanation: Both antisera and antitoxins are means of proactively combating infections. The introduction of compounds to which the immune system responds is an attempt to build up protection against microorganisms or their toxins before the microbes actually invade the body.

Explanation: Serum must be filtered sterilized, and contamination with viruses and possibly mycoplasma (a wall less bacterium) are potential problems. Contamination by prions (agents that cause diseases such as “mad cow” disease) is a real concern, and source animals cannot come from regions known to have contaminated animals.

Explanation: Eagle’s minimal essential medium (EMEM) is a cell culture medium developed by Harry Eagle that can be used to maintain cells in tissue culture.

Explanation: A simpler serum-free medium may contain insulin, transferrin, and selenium as serum replacement components, in addition to glucose, glutamine, other amino acids, and salts.

Explanation: Animal cells are very shear sensitive, and rising air bubbles may cause shear damage to cells, particularly at the point of bubble rupture. Very small bubbles are less damaging.

Explanation: Poloxamers are nonionic triblock copolymers composed of a central hydrophobic chain of polyoxypropylene (poly(propylene oxide)) flanked by two hydrophilic chains of polyoxyethylene (poly(ethylene oxide)). Poloxamers are also known by the trade names Synperonics, Pluronics, and Kolliphor.

Explanation: Spinner flasks contain a magnetically driven impeller or spoonlike agitators that operate at 10 to 60 rpm. Aeration is usually by surface aeration using 5% CO2-enriched and filtered air for mammalian cell lines. Spinner flasks are set on a magnetic stirrer plate in a CO2 incubator.