Hfr Strains and Genetic Mapping by the Time of Entry

Question 1

How are Hfr strains formed?

Answer 1

Hfr strains are formed by homologous recombination between homologous sequences (such as insertion sequences and transposons).

Question 2

How can conjugation be used to map chromosomes by ‘time of entry.’?

Answer 2

As conjugation transfer from a fixed origin (oriT), you can measure the order of the genome based on the proportion of measurable markers