Final answer:
In conjugation between Hfr and F- cells, part of the Hfr cell's chromosomal DNA is transferred to the F- cell via a mating bridge, with genes close to the insertion site transferring first. The entire chromosome is seldom transferred due to the temporary nature of cell contact. Eventually, the recipient cell can become Hfr if it successfully integrates the transferred material.
Step-by-step explanation:
The result of conjugation between Hfr and F- cells in E. coli involves the partial transfer of chromosomal DNA from the Hfr (High-frequency recombination) cell to the recipient F- cell. An Hfr cell is a bacterial cell with an F factor (fertility plasmid) integrated into its chromosome. During conjugation, a mating bridge is formed, and one strand of the bacterium's chromosomal DNA is transferred to the F- cell.
This process begins at the insertion site of the F plasmid into the bacterial chromosome and continues usually until the conjugation bridge breaks. Notably, the entire chromosome is rarely transferred because the cell-to-cell contact is typically too brief. Any genes located near the point of origin will transfer first and have a higher chance of recombination in the recipient's chromosome.
Over time and through multiple conjugation events, this can lead to the recipient cell becoming an Hfr cell itself if it integrates the transferred genes and the remnants of the F plasmid into its own chromosome.