Transduction by Sivasangari Shanmugam. Transduction is the genetic material that is transferred by bacteriophage.

1. TRANSDUCTION
SIVASANGARI SHANMUGAM

2. INTRODUCTION
 DNA fragment is transferred from one bacterium to another bacterium by a
bacteriophage.
 Discovered on 1951 by Lederberg & Zinder in Salmonella & P22.
 There are two types of transduction. They are,
1. Generalized Transduction
2. Specialized Transduction

3. BACTERIOPHAGE
 Bacteriophage is a type of virus that
infects bacteria .
 All bacteriophage composed of a
nucleic acid molecule that is surrounded
by a protein structure.
 A bacteriophage attaches itself to a
susceptible bacterium and infects the
host cell.
 Bacteriophage occasionally remove a
portion of their host cell’s bacterial
DNA during the infection process and
the transfer this DNA into the genome
of new host cells. This process is known
as transduction.

4. GENERALIZED TRANSDUCTION
 In generalized transduction, phage mistakenly packages bacterial DNA
instead of their own phage DNA during phage assembly.
 This results in an infectious virus particle containing bacterial DNA, but
one that can no longer replicate in the bacterium due to the loss of all of the
phage DNA.
 The phage particle then attaches to a bacterial cell surface receptor and
injects the packaged DNA into the cytoplasm of the bacterium.

5.  If the bacterial DNA in the phage is from the bacterial chromosome, the
DNA recombines with the homologous DNA of the bacterial recipient to
generate stable transductants. This process requires a host recombinase,
recA.
 However, studies have indicated that the majority of transduced DNA is not
stably integrated into the bacterial genome but rather remains extra
chromosomal.
 Generalized transduction is used for mapping genes, mutagenesis,
transferring plasmids and transposons, and determining whether different
genera of bacteria have homologous genes.

7. SPECILIZED TRANSDUCTION
 In specialized transduction, the phage undergoes lysogeny usually at
specific locations in the bacterial genome called attachment sites.
 During this process, the phage genome usually integrates into the bacterial
chromosome as virus replication is repressed during lysogeny.
 The phage genome then excises from the bacterial genome and, due to
imprecise excision and recombination, adjacent bacterial genes are also
excised.
 During the subsequent infection, the newly acquired gene is inserted into
the bacterial genome along with phage DNA to form a new round of
lysogeny.

8.  Specialized transduction is independent of host homologous recombination
and recA but requires phage integrase.
 Specialized transduction is instrumental in the isolation of the genes in
molecular biology, and in the discovery of insertion elements, which often
serve as attachment sites for phage DNA integration.

10. THANK YOU