BISC 202 Lecture Notes - Lecture 18: Circular Bacterial Chromosome, Hfr Cell, Plasmid
4 Jan 2019
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Prokaryotic genetics study guide: prokaryotic reproduction: binary ssion, produce genetically identical daughter cells, prokaryotic sex: A donor cell (f+ or hfr) contains f-plasmid containing genes that can recognize f- cells and build conjugation pillus. F+ cell: circular bacterial chromosome and circular plasmid. Hfr cell: the circular plasmid is integrated into the chromosome through crossing over. F- cell: does not have the f-plasmid. The donor cell builds a pillus and attaches to a f- cell and draws the cells together. One strand of the donor"s plasmid dna transfers to the recipient f- cell. The recipient cell synthesizes a complementary strand by dna replication to become an f+ cell. The donor synthesizes another complementary strand, restoring its complete plasmid. F+ is still f+ after conjugation because it still has the f-plasmid. F- becomes f+ because now it has the f- plasmid. Hfr is still hfr because it still has the f-plasmid. F- rarely becomes f+ because conjugation is easier to be interrupted.
