Final answer:
Insertion by recombination involves attachment sites known as inverted repeats in the case of transposons and occurs at specific sites for the F plasmid integration into bacterial DNA to form an Hfr cell.
Step-by-step explanation:
Insertion occurs by recombination between attachment sites during the process of genetic recombination. These attachment sites are called inverted repeats when dealing with transposons, which are cut from their original location and inserted into a new location. In the context of homologous recombination during meiosis, the process involves recombination nodules located at intervals along the synaptonemal complex. These nodules mediate the multistep process of crossover or genetic recombination. In the case of the F plasmid insertion into bacterial chromosomal DNA, insertion typically occurs at specific sites where there is sufficient sequence similarity to allow insertion by recombination, resulting in an Hfr (High-frequency recombination) cell.