Cell fusion - formation of a single hybrid cell from two cells of different species, cultured in vitro. The cells fuse and coalesce, but their nuclei may remain separated. During subsequent cell division, a single spindle is formed so that each daughter cell has a single nucleus. containing sets of chromosomes from each parental line. Subsequent divisions often result in the loss of chromosomes and therefore of genes. The cell fusion technique can be used to determine the control of specific genes and their assignment to chromosomes. if cell hybridisation.

Cell generation time - the interval between the beginning of consecutive divisions of a cell. The time that it takes for a population of single-celled organisms to double its cell number. Successsive generation of cells or organisms within a population are separated by a time interval called generation time. The cell regeneration time can be determined with the aid of time-lapse microcinematography.

Cell membrane - the membrane that separates the cell wall and the cytoplasm, and regulates the flow of material into and out of the cell. See plasmalemma.

Cell sap - water and dissolved substances, sugar, amino acids, waste substances, etc., in the plant cell vacuole.

Cell selection - the process of selecting cells within a group of genetically different cells. Select cells or cell lines are subcultured onto fresh medium for continued selection and often are exposed to an increased level of the selection agent. The final objective is to regenerate plants exhibiting the traits selected for at the cellular level.

Cell strain - a strain of cells having specific properties or markers derived from a primary culture of a cell line by selection or cloning. The selected properties must persist during subsequent cultivation. a.k.a. single cell line.

Cell suspension - cells in culture in moving or shaking liquid medium, often used to describe suspension cultures of single cells and cell aggregates. See suspension culture.

Cell wall - a rigid external coat which surrounds plant cells. It is formed outside the plasmale and consists primarily of cellulose.

Cell mediated immune response - the activation of T cells of the immune system in response to the presence of a foreign antigen.

Cellular oncogene - a normal mammalian or avian gene that mutated or improperly expressed contributes to the development of cancer.

Cellulase - enzyme catalysing the breakdown of cellulose.

Cellulose - a complex carbohydrate composed of long, unbranched chains of beta-glucose ((1.4)linked-b-d-glucose) molecules, which contribute to the structural framework of . plant cell walls. It comprises. 40% to 55% by weight of the plant cell wall.

Cellulose nitrate - see nitrocellulose.

Cellulosome - a multi-protein aggregate that: is present in some cellulolytic micro-organisms and contains multiple copies of all the enzymes required to completely break down cellulose. This complex is often found on the outer surface of cellulolytic microorganisms.

centiMorgan (cM) - one percent recombination between two loci.

Central dogma - the basic concept that, in nature, genetic information generally can flow only from DNA to RNA to protein. It is now known, however, that information contained in RNA molecules of certain viruses (called retroviruses) can also flow back to DNA.

Central mother cell - a subsurface cell located in a plant apical meristem and characterised by a large vacuole.

Centres of origin - the locations in the world where particular domesticated plants originated. These areas show the highest variation, and are rich in wild alleles.

Centrifugation - separating molecules by size or density using centrifugal forces generated by a spinning rotor. G-forces of several hundred thousand times gravity are generated in ultracentrifugation.

Centrifuge - a device in which solid or liquid particles of different densities are separated by rotating them in a tube in a horizontal circle. The denser particles tend to move along the length of the tube to a greater radius of rotation, displacing the lighter particles to the other end.

Centriole - an organelle in many animal cells that appears to be involved in the formation of the spindle during mitosis. During cell division, the two centrioles move to opposite sides of the nucleus to form the ends of the spindle.

Centromere - the portion of the chromosome to which the spindle fibres attach during mitotic and meiotic division. It appears as a constriction when chromo somes contract during cell division. After chromosomal duplication, which occurs at the beginning of every mitotic and meiotic division, the two resultant chromatids are joined at the centromere.

Centrosome - a specialised region of a living cell, situated next to the nucleus, where microtubules are assembled and broken down during cell division. The centrosome of most animal cells contains a pair of centrioles. During metaphase the centrosome separates into two regions, each containing one of the centrioles.

Cephem type antibiotic - an antibiotic that shares the basic chemical structure of cephalosporin.

Chain terminator - 1. codons which do not code for an amino acid. They signal ribosomes to terminate protein synthesis. The codons are UAA, UAG and UGA, and have been termed ochre, amber and opal, respectively. Also known as stop codons or termination codons. Often two of these codons are found together at the end of a coding sequence of RNA.
2. in the Sanger method of DNA sequencing, dideoxynucleoside triphosphates are added as chain terminators in the synthesis of a complementary DNA strand.

Character - a distinctive feature of an orgamsm.

Chelate - noun: complex organic molecule that can combine with cations and does not ionize. Chelates can supply micronutrients to plants at slow, steady rates. Usually used to supply iron to plant cells.