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HFr strains are bacterial strains with Hfr DNA or F plasmid DNA integrated into bacterial chromosomes. Bacterial strains which contain F plasmids are known as F+ strains. F plasmids contain fertility factor coding genes. The fertility plasmid is integrated into the host cell chromosomal DNA in Hfr cells.
What is the difference between F+ cells and HFR cells?
Hfr (High frequency of recombination) Cells = Derivatives of F+ cells where F plasmid has integrated into host chromosomal DNA. So when this integration happens, the resultant cells or the derivative of F+ cells is called Hfr cells.
Why does conjugation between an Hfr strain and an F strain not result in two Hfr strains?
Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains? Conjugation is typically disrupted before the fertility factor can be transferred. Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.
What is the difference between F+ and Hfr cells?
Hfr (High frequency of recombination) Cells = Derivatives of F+ cells where F plasmid has integrated into host chromosomal DNA. This F plasmid is an episome which means it can either exist as an independent unit or it can integrate itself into chromosomal DNA.
What occurs when an F+ cell is mated to a F cell?
What occurs when a F+ cell is mated to a F- cell? An Hfr strain (met+,his+, arg+, strs) is mated with an F- strain (met-, his-, arg-, strr), grown in complete media, then plated on minimal media supplemented with streptomycin, histidine, and arginine.
Why does conjugation with an Hfr donor?
Why does conjugation with an Hfr donor result in a much higher rate of gene transfer than conjugation with an F+ donor? The Hfr donor transfers genes from the chromosome and not the plasmid. When F+ conjugation occurs successfully, only one copy of the F plasmid single-stranded DNA is transferred.
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