| 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) |
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| f-2 generation | <genetics> Filial-Two generation. The generation of offspring which results from mating or genetically crossing members of the F-1 generation to each other. Members of this generation are two generations removed from the original parent generation, or the P generation. (09 Oct 1997) |
| F-factor | <molecular biology> A small piece of episomal bacterial DNA (plasmid) which provides bacteria with the ability to initiate conjugation (bacterial mating) with other nearby bacteria. It can be present as extrachromosomal protein or integrated into the bacterial chromosome, and effectively determines the 'sex' of the bacterium, host chromosome mobilization, transfer via conjugation of genetic material, and the formation of sex pili. During conjugation, the F-factor is copied and passed on to the other bacterium so that it acquires the ability to initiate conjugation also. (12 Jul 2000) |
| f-number | <radiobiology> In optics, denotes the ratio of the equivalent focal length of an objective lens to the diameter of its entrance pupil. (09 Oct 1997) |
| F-type ATPase | <enzyme> One of three major classes of ion transport ATPase, characterised by a multi subunit structure and a lack of a phosphorylated intermediate. See: ATP synthase, P-type ATPase, V-type ATPase. (18 Nov 1997) |