F: “F” can have several different related definitions:

• An F plasmid is a type of naturally occurring low copy number plasmidplugin-autotooltip__default plugin-autotooltip_bigPlasmid: a circular episome found in bacteria and yeast. Plasmids are commonly used as cloning vectors. in E. coliplugin-autotooltip__default plugin-autotooltip_bigEscherichia coli: an enteric bacterium used both as a model organism and as a utility organism in genetics research. E. coli is commonly used to host various cloning vectors, such as plasmids, cosmids, F factors, and bacterial artificiak chromosomes (BACs). that can move from one host cell to another via conjugation, a type of sex in bacteriaplugin-autotooltip__default plugin-autotooltip_bigBacteria: Single-celled organisms that also utilize DNA and the standard genetic code as all organisms on earth, but unlike eukaryotes do not have intracellular membranes and membrane-bound organelles. In this book we use bacteria and prokaryote interchangeably. (“F” stands for fertility). F plasmids are also referred to as simply “F”
• F⁺ refers to an E. coliplugin-autotooltip__default plugin-autotooltip_bigEscherichia coli: an enteric bacterium used both as a model organism and as a utility organism in genetics research. E. coli is commonly used to host various cloning vectors, such as plasmids, cosmids, F factors, and bacterial artificiak chromosomes (BACs). strainplugin-autotooltip__default plugin-autotooltip_bigStrain or line: refers to a pool or colony of individuals or cultured cells of a desired genotype or phenotype that is mostly homogeneous and can be bred and/or produced in perpetuity for research or commercial purposes. “Strain” tends to be used more for microorganisms and that contains F.
• F^- refers to an E. coliplugin-autotooltip__default plugin-autotooltip_bigEscherichia coli: an enteric bacterium used both as a model organism and as a utility organism in genetics research. E. coli is commonly used to host various cloning vectors, such as plasmids, cosmids, F factors, and bacterial artificiak chromosomes (BACs). strainplugin-autotooltip__default plugin-autotooltip_bigStrain or line: refers to a pool or colony of individuals or cultured cells of a desired genotype or phenotype that is mostly homogeneous and can be bred and/or produced in perpetuity for research or commercial purposes. “Strain” tends to be used more for microorganisms and that does not contain F or any of its derivatives.
• F^' (pronounced “F prime”) refers to an F derivative that contains a portion of the E. coliplugin-autotooltip__default plugin-autotooltip_bigEscherichia coli: an enteric bacterium used both as a model organism and as a utility organism in genetics research. E. coli is commonly used to host various cloning vectors, such as plasmids, cosmids, F factors, and bacterial artificiak chromosomes (BACs). chromosomeplugin-autotooltip__default plugin-autotooltip_bigChromosome: a structure that organizes dsDNA in a cell through interactions with various DNA binding proteins..
• Hfr (high frequency recombinationplugin-autotooltip__default plugin-autotooltip_bigRecombination: Recombination can have slightly different meanings depending on context:
  
  * In the context of genetic crosses (usually a dihybrid cross or a test cross), recombination refers to the phenomena where the phenotype of the F2 offspring is different than either parent (P generation). $lox$) is a strainplugin-autotooltip__default plugin-autotooltip_bigStrain or line: refers to a pool or colony of individuals or cultured cells of a desired genotype or phenotype that is mostly homogeneous and can be bred and/or produced in perpetuity for research or commercial purposes. “Strain” tends to be used more for microorganisms and of E. coliplugin-autotooltip__default plugin-autotooltip_bigEscherichia coli: an enteric bacterium used both as a model organism and as a utility organism in genetics research. E. coli is commonly used to host various cloning vectors, such as plasmids, cosmids, F factors, and bacterial artificiak chromosomes (BACs). in which F has integrated into the chromosomeplugin-autotooltip__default plugin-autotooltip_bigChromosome: a structure that organizes dsDNA in a cell through interactions with various DNA binding proteins..