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