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MOLECULAR BIOLOGY, CELL CULTURE, IMMUNOLOGY, HUMAN PHYSIOLOGY

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C domains The constant domains of immunoglobulin molecule and the T-cell receptor. These domains do not contribute to the antigen-binding site and show relatively little variability between receptor molecules.

C genes The gene segments encoding the C domains of immunoglobulin and the T-cell receptor.

Cadherins
A family of Ca2+-dependent cell-adhesion molecules that play roles in tissue differentiation and structure.

Calcitonin Peptide hormone secreted by thyroid gland that may play a role in regulation of plasma calcium.

Calmodulin A small cytosolic protein that binds four Ca2+ ions; the Ca2+-calmodulin complex binds to and activates many enzymes.

CAMs = Cell adhesion molecules

Capsid The protein coat that encloses the DNA or RNA molecule of a bacteriophage or virus.

Carcinogen Any chemical or physical agent that can cause cancer when cells or organisms are exposed to it.

Carcinoma A malignant tumor derived from epithelium, usually from endodermally or ectodermally derived cells.

Cassette A DNA sequence consisting of promoter - ribosome binding site - unique restriction site - terminator (or, for a eukaryotic host , promoter -unique restriction site - polyadenylation sequence) carried by certain types of expression vector. A foreign gene inserted into the unique restriction site will be placed under control of the expression signals.

Catabolism
Cellular processes whereby complex molecules are degraded to simpler ones and energy is released. Opp. Anabolism.

Cauliflower mosaic virus (CaMV)
The best studied of the caulimoviruses, used as a cloning vector for some species of higher plant.

Caulimoviruses One of the two groups of DNA viruses to infect plants, the members of which have potential as cloning vectors for some species of higher plant.

cDNA = Complementary DNA.

Cell adhesion molecules A group of proteins of the immunoglobulin supergene family involved in intercellular adhesion, including ICAM-1, ICAM-2, ICAM-3, VCAM-1, MAdCAM-1 and PECAM.

Cell culture In vitro growth of cells dissociated from the parent tissue of animals and plants by spontaneous migration or mechanical or enzymatic dispersal.

Cell extract A soluble preparation consisting of a large number of broken cells and their released contents such as proteins, nucleic acids, carbohydrates, peptides, and fatty acids.

Cell-free translation system A cell extract consisting all the components required for protein synthesis (i.e. ribosomal subunits, tRNAs, amino acids, enzymes and cofactors) and able to translate added mRNA molecules.

Cell fusion Formation of single cell body by fusion of two other cells; either spontaneously or, more often, by induced fusion with inactivated Sendai virus or polyethylene glycol.

Cell hybridization = Hybrid cell

Cell junctions Specialized regions on the cell surface through which cells are joined to each other: tight junctions are ribbon like bands connecting adjacent epithelial cells that prevent leakage of fluid across the cell layer. Gap junctions are protein-lined channels between adjacent cells that allow passage of ions and small molecules between the cells. Desmosomes and adherens junctions consist of dens protein plaques connected to intermediate filaments that mediate adhesion between adjacent cells and between cells and the extracellular matrix.

Cell-mediated immunity
A term used to refer to immune reactions that are mediated by cells rather than by antibody or other humoral factors.

Cell Line A propagated culture of a single cell after the first sub-culture

Cell strain A characterized cell line derived by selection or cloning

Central nervous system (CNS) The part of the vertebrate nervous system comprising the brain and spinal cord; the main information-processing organ.

Centriole Either of two cylindrical structures within the centrosome of animal cells and containing nine sets of triplet microtubules; structurally similar to a basal body.

Centromere Region of a chromosome required for proper chromosome segregation during mitosis and meiosis; the region where sister chromatids in mitotic chromosomes are attached and from which kinetochore fibers extend toward a spindle pole.

Chaperone Any protein that binds to an unfolded or partially folded target protein, thus preventing misfolding, aggregation, and/or degradation of the target protein and facilitating its proper folding.

Chemically defined Used of medium to imply that it is made entirely from pure defined constituents. Distinct from "serum-free", where other poorly characterized constituents may be used to replace serum

Chemiosmosis Process whereby an electrochemical proton gradient (pH plus electric potential) across a membrane is used to drive ATP synthesis, to pump metabolites across the membrane against their concentration gradient, or to power the rotation of bacterial flagella.

Chemotaxin Any chemical that causes chemotaxis.

Chemotaxis Increased directional migration of cells particularly in response to concentration gradients of certain chemotactic factors.

Chiasma Point at which non sister chromatids of homologous chromosomes cross each other during meiosis.

Chondrocyte Cell type that forms new cartilage.

Chimaera A recombinant DNA molecule made up of DNA fragments from more than one organism, named after the mythological beast.

Chromatid One of a pair of homologous chromosomes, formed during the S phase of the cell cycle, that is still joined at the centromere to its homolog. During mitosis, the two chromatids separate, each becoming a chromosome of one of the two daughter cells.

Chromatin Complex of DNA, histone, and nonhistone proteins present in the nucleus of eukaryotic cells. It exists in two forms: a less condensed form which can be transcribed (euchromatin) and a highly condensed form which is generally not transcribed (heterochromatin). Condensation of chromatin during mitosis yields the visible metaphase chromosomes.

Chromosome A self-replicating nucleic acid molecule carrying a number of genes.

Chromosome walking A technique used to identify a series of overlapping restriction fragments, often to determine the relative positions of genes on large DNA molecules.

Chyme Solution of partially digested food in stomach and intestinal lumens.

Cilium (pl. cilia) Membrane-enclosed motile structure extending from the surface of eukaryotic cells and composed of a specific arrangement of microtubules forming the axoneme. Cilia usually occur in groups and beat rhythmically to move an cell (e.g., single-celled organism) or to move small particles or fluid along the surface (e.g., trachea cells).

Cisterna (pl. cisternae) Flattened membrane-bounded compartment present in the Golgy complex and endoplasmic reticulum in various tissues.

Cistron A genetic unit that encodes a single polypeptide.

Class I MHC molecules One of the MHC (major histocompatibility complexes), which have one MHC-encoded peptide complexed with β2-microglobulin.

Class II MHC molecules One of the MHC (major histocompatibility complexes), which have two MHC-encoded peptides that are non-covalently associated.

Class III MHC molecules One of the MHC (major histocompatibility complexes), which are other molecules including complement components.

Classical pathway The pathway by which antigen-antibody complexes can activate the complement system, involving components C1, C2 and C4, and generating a classical pathway C3 convertase. Opp. Alternative pathway.

Class switching The process by which an individual B cell can link immunoglobulin heavy chain C genes to its recombined V gene to produce a different class of antibody with the same specificity. This process is also reflected in the overall class switch seen during the maturation of an immune response.

Clone A population of identical cells, generally those containing identical recombinant DNA molecules.

CMI = Cell-mediated immunity.

CNS = Central Nervous System.

Collagen A triple-helical protein that forms fibrils of great tensile strength; a major component of the extracellular matrix and connective tissues. The numerous collagen subtypes differ in their tissue distribution and the extracellular components and cell-surface proteins with which they associate.

Colony stimulating factor A group of cytokines which control the differentiation of haemopoietic stem cells.

Coma Deep, prolonged unconsciousness not fulfilling all the criteria for brain death; thus, there may be spontaneous movement and some intact reflexes.

Compatibility Refers to the ability of two different types been treated to enhance their ability to take up DNA molecules.

Complement A group of serum proteins involved in the control of inflammation, the activation of phagocytes and the lytic attack on cell membranes. The system can be activated by interaction with the antibodies of the immune system (classical pathway).

Complementary
Refers to two polynucleotides that can base-pair to form a double-stranded molecule.

Complementary DNA (cDNA)
A DNA molecule which has complementary base sequence to a certain DNA.

Complementary DNA (cDNA) cloning
A cloning technique involving conversion of purified mRNA to DNA before insertion into a vector.

Complementary DNA (cDNA) library
Collection of cloned DNA molecules consisting of DNA copies of all the mRNAs produced by a cell type inserted into a suitable cloning vector.

Complementation In genetics, the restoration of a wild-type function (e.g., ability to grow on galactose) in diploid heterozygotes generated from haploids each of which carries a mutation in a different gene whose encoded protein is required for the same biochemical pathway. Complementation analysis of a set of mutants exhibiting the same mutant phenotype (e.g., inability to grow on galactose) can be used to determine if mutations are in the same or different genes.

Confluent Where all the cells are in contact all around their periphery with other cells, and no available substrate is left uncovered

Conformation The spatial organization of a molecule. Linear and circular are two possible conformations of a polynucleotide.

Congenic animals
Animals which are genetically constructed to differ at one particular locus.

Conjugation
Physical contact between two bacteria, usually associated with transfer of DNA from one cell to the other.

Consensus sequence
A nucleotide sequence in which the base present in a given position is that base most commonly found when many experimentally determined sequences are compared.

Constitutive mutant (1) A mutant in which a protein is produced at a constant level, as if continuously induced; (2) a bacterial regulatory mutant in which an operon is transcribed in the absence of inducer. (3) A mutation in which a regulated enzyme is in a continuously active form.

Contact inhibition Inhibition of cell membrane ruffling and cell motility when cells are in complete contact with other adjacent cells, as in a confluent culture. Often precedes cessation of cell proliferation but not necessarily causally related

Continuous cell line or cell strain One having the capacity for infinite survival. Previously known as "established" and often referred to as "immortal"

Continuous culture The culture of microorganisms in liquid medium under controlled conditions, with additions to and removals from the medium over a lengthy period of time.

Contour clamped homogeneous electric fields (CHEF) An electrophoresis technique for the separation of large DNA molecules.

Copy number The number of molecules of a plasmid contained in a single cell.

Cos site One of the cohesive, single-stranded extensions present at the ends of the DNA molecules of certain strains of λ phage.

Cosmid A cloning vector consisting of the λ cos site inserted into a plasmid, used to clone DNA fragments up to 40 kb in size.

Cotransport Protein-mediated transport of an ion or small molecule across a membrane against a concentration gradient driven by coupling to movement of a second molecule down its concentration gradient. Opp. Symport.

Covalent bond Chemical bond between two atoms in which each atom shares one of its electrons with the other.

Covalently closed-circular (CCC) A completely double-stranded circular DNA molecule, with no nicks or discontinuities, usually with a supercoiled conformation.
Creatinine Waste product derived from muscle creatine.

Crossing over Exchange of genetic material between nonsister chromatids of homologous chromosomes during meiosis to produce recombined chromosomes.

Cumulus oophorous Granulosa cells surrounding egg where egg projects into ovarian follicle antrum.

Cyclic growth
Growth from a low cell density to a high cell density with a regular subculture interval. A regular repetition of the growth cycle for maintenance purposes

Cyclin Any of several related proteins many of whose concentrations rise and fall during the course of the eukaryotic cell cycle. Cyclins form complexes with cyclon-dependent protein kinases, thereby activating and determining the substrate specificity of theses crucial enzymes which regulate passage through the cell cycle.

Cyclosporin A T-cell suppressive drug that is particularly useful in suppression of graft rejection.

Cytokines A generic term for soluble molecules which mediate interactions between cells, especially influence cells of the immune system. These are secreted by macrophages, monocytes (monokine), Lymphocytes (lymphokine) and other cells.

Cytotoxic T cells Cells which can kill virally infected targets expressing antigenic peptides presented by MHC Class I molecules.

Cytoplasm Viscous contents of a cell that are contained within the plasma membrane but, in eukaryotic cell, outside the nucleus. The part of the cytoplasm not contained in any organelle is called the cytosol.

Cytosol = Cytoplasm.

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Cell culture Products
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- Fetal Bovine Serum (FBS), ES Cell-Qualified