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MICROBIOLOGYCONJUGATION
Meghna VIII Semester
MGMCH
BACTERIAL CONJUGATION WAS FIRST DISCOVERED BY
Lederberg And TatumIN 1946
IN Esch.coliK12 STRAINS
CONJUGATION
BACTERIA A BACTERIA B
TRANSFER OF GENETIC MATERIAL FROM BACTERIA A TO BACTERIA B BY MATING OR CONTACT IS CALLED
CONJUGATION.
WHO IS A DONOR?
F PLASMID ABSENTDONOR RECIPIENTF + F –MALE CELL FEMALE
F PLASMID
FERTILITY FACTORSEX FACTOR
TRANSFER FACTOR
THIS F PLASMID ENCODES FOR THE SEX PILUS
WHAT HAPPENS DURING CONJUGATION?
THE ONCE FEMALE RECIPIENT CELL NOW BECOMES THE MALE DONOR CELL
THIS CHARACTERISTIC OF MALENESS (F+) IN BACTERIA IS TRANSMISSIBLE OR
INFECTIOUS
What is Hfr cell?
When F factor/ plasmid exists in an integrated state with the host chromosome
Hfr CONJUGATION
F+ (free plasmid) Hfr ( integrated )
REVERSIBLE
TURNS A (F-) CONJUGATION WITH A
INTO A (F+) UPON Hfr , AN (F-) RARELY
CONJUGATION BECOMES (F+) BUT IT
RECEIVES CHROMOSOMAL
DNA FROM THE
DONOR
REVERSIBLE
(F+) Hfr
SEXDUCTION
F+ HfrREVERSIBLE
WHEN THE F FACTOR REVERTS FROM INTEGRATED FREE STATE IT MAY
SOMETIMES CARRY WITH IT SOME CHROMOSOMAL DNA FROM ADJACENT
SITE OF ITS ATTACHMENT
SUCH AN F FACTOR IS KNOWN AS F’ FACTOR
( F’) + ( F-) SEXDUCTION
WHEN (F’) CONJUGATES WITH A RECIPIENT (F-), IT TRANSFERS, ALONG WITH THE F FACTOR,
THE HOST DNA INCORPORATED WITH IT.
MEDICALLY IMPORTANT FACTORS WHICH CAN BE TRANSFERRED BY CONJUGATION
1. COLICOGENIC FACTOR (COL)2. RESISTANCE TRANSFER FACTOR (RTF)
THANKYOU