Fibroblast A connectivetissue cell that secretes proteins such as collagen.

Fibroblast growth factors (FGFs) A family of secreted signaling proteins that play a role in animal tissue development. These proteins are mitogenic or angiogenic. The receptors for FGF are tyrosine kinases. Mutations in FGF receptors are associated with inherited human birth defects.

Fick’s law diffusion The hypothesis that a substance in solution will diffuse in a direction hat will eliminated any concentration gradient by making the solution homogenous.

Ficoll An inert, synthetic polymer of glucose. It is used to increase the density of solution for density gradient centrifugation and nucleic acid hybridization.

Figlu excretion test A diagnostic test for folate deficiency. In patients with folate deficiency, a histidine load causes increased excretion of formiminoglutamate (figlu) in the urine.

Figure eight Two circle of DNA that are linked together by a recombination event that is still incomplete.

Fibrinogen (Factor I) A clotting factor that is converted to fibrin (Factor la) by the action of thrombin. Fibrinogen is a large, stable molecule made of three pairs of polypeptide chains (Aα,Bβ and γ). Cleavage by thrombin releases two pairs of A and B fibrinopeptides from the Aα and Bβ chains. Fibrin monomers that remain after the release of the peptides aggregate to form the soft clot, which is converted to a hard clot by factor XIIIa

Filamentous bacteriophageA subclass of single-stranded DNA bacteriophage encapsidated by an elongated, filamentous viral coat. The common members of this class of bacteriophages include F1 and M13.

Filamin An intracelluelar anchor protein that links the intracellular domains of integrins to the actin filaments.

File A discrete collection of bytes on a computer that can be manipulated as a single entity. A named location on a computer’s storage device.

Filial generation See F1; F2.

Filopodia Long microspikes of 50 μm extending out of the growing tip of the axon of a developing neuron.

Filter bioreactor A bioreactor in which the cells are grown on an open mesh of an inert material that permits the culture medium to pass through but retains the cells. Also called mesh bioreactor.

Filter hybridization A type of hybridization in which denatured DNA immobilized on a nitrocellulose filter is incubated with a radioactively labelled DNA or RANA.

Filter sterilization The process of sterilising a liquid by passage through a filter with pores that are small enough to prevent the passage of microorganism and microbial spores.

Filtering The process of making regions of nucleic acid or amino acid sequence that contain characteristics that lead to spurious high scores.

Filters Wavelenght selectors that absorb light in all other regions except the one they reflect. Filters resolve polychromatic These may be made of a layer of gelatin coloured with organic dyes and sealed between glass plates. Modern filters are made of tinted glass. In genera, the filter transmits as this would absorb red light.

Filtration 1. Separation of solids from liquids by using a porous material that allows movement of the liquid or of solids that are smaller than the pore size of the filter. The material that passes the filter forms the filtrate. 2. The removal of cell aggregates in order to obtain a filtrate of single cells that can be used as plating inocula.

FindMed A tool that predicts specific posttranslational modification of proteins based on differences between experimental and computed fingerprints.

Fine structure mapping A mapping technique that detects changes in nucleotide base sequence based on rare recombination events between strands of DNA carrying different forms o the same gene (alleles).

Fines Very small particles in an ion exchanger that decrease the flow rate. These can be removed by particles suspending the ion exchanger in large volumes of water. After large polymers settle down, the fines that float can be decanted.

Fingerprint 1. The pattern of polymorphic DNA restriction fragments that shows individual variations. It is useful for differentiating individual genomes. 2. The pattern of bands generated by cleavage of a protein with an enzyme such as trypsin. 3. A set of motifs used to predict the occurrence of similar motifs, in either an individual sequence or in a database. Fingerprints are refined by iterative scanning of composite protein sequence database. A composite or multiple-motif fingerprint consists of aligned motifs obtained from different parts of a multiple alignment. True family members can be identified based on possession of all elements of the fingerprint whereas subfamily members may be identified by possession of only part of the elements.