| F | <immunology> The portion of the immunoglobulin or antibody molecule which contains the binding site for antigens. The exact sequence of amino acids in the area varies widely from molecule to molecule to accommodate a wide variety of antigens which the body may encounter. There are two such regions on each molecule (individually called Fab fragments or f-ab fragments). The molecule is shaped like the letter Y and the F(ab)2 fragments are located on the upper halves of the two fork parts. (The rest of the molecule, the stem and the lower parts of the forks, are the Fc fragment). (08 Mar 2000) |
|---|---|
| F actin | <cell biology> Plasmid that confers the ability to conjugate (i.e. Fertility) on bacterial cells and carries the tra genes. It was first described in E. Coli. (18 Nov 1997) |
| F agent | The prototype conjugative plasmid associated with conjugation in the K-12 strain of Escherichia coli. Synonym: F agent, F-factor, F genote, F-genote, fertility agent, fertility factor, sex factor. (05 Mar 2000) |
| f distribution | The distribution of the ratio of two independent quantities each of which is distributed like a variance in normally distributed samples. So named in honor of the English statistician and geneticist R.A. Fisher. (05 Mar 2000) |
| F duction | Transfer of chromosomal fragments from one bacterium to another by means of F' carriers. Synonym: sexduction. (05 Mar 2000) |
| F genote | The prototype conjugative plasmid associated with conjugation in the K-12 strain of Escherichia coli. Synonym: F agent, F-factor, F genote, F-genote, fertility agent, fertility factor, sex factor. (05 Mar 2000) |
| F pili | See: pilus. F pilus, a structure responsible for attachment of individual male (F+) to female (F-) bacteria, forming conjugal pairs. (05 Mar 2000) |
| f pilus | A long, narrow structure which protrudes from the surface of the male bacterial individual and connects the male to the female bacterial individual during the process of bacterial conjugation, when genetic material in the form of the f plasmid is transferred between individual bacterial cells. (09 Oct 1997) |
| F plasmid | The prototype conjugative plasmid associated with conjugation in the K-12 strain of Escherichia coli. Synonym: F agent, F-factor, F genote, F-genote, fertility agent, fertility factor, sex factor. (05 Mar 2000) |
| f protein | <protein> A protein derived from the Sendai virus which can be used in the laboratory to cause cell fusion between somatic cells (any cell that is not a gamete). It is also used to make fusogenic vesicles. (09 Oct 1997) |
| F thalassaemia | Thalassaemia due to a gene that depresses synthesis of both beta-and d-globin chains by the chromosome bearing the abnormal gene. Heterozygous state: thalassaemia minor with Hb F comprising 5 to 30% of total haemoglobin but distributed unevenly among cells, Hb A2 reduced or normal. Homozygous state: moderate anaemia with only Hb F present, no Hb A or Hb A2. Synonym: F thalassaemia. (05 Mar 2000) |
| f urcation | 1. A forking, or a forklike part or branch. 2. In dental histology, the region of a multirooted tooth at which the roots divide. Origin: L. Furca, fork (05 Mar 2000) |
| F waves | The waves of atrial flutter usually best seen in ECG leads 2, 3, and AVF. (A small f indicates atrial fibrillation). Synonym: fibrillary waves, fibrillatory waves, flutter-fibrillation waves. (05 Mar 2000) |
| F(6) ATPase | <enzyme> One of f(0)'s subunits needed for binding of f(1) to f(0) Registry number: EC 3.6.1.- Synonym: coupling factor 6, atpase, f(6) (26 Jun 1999) |
| f-1 generation | <genetics> Filial-One generation. The first generation of offspring which results after mating or genetically crossing two types of parents with different genotypes or phenotypes. (The parents are known as the P generation.) (09 Oct 1997) |