Bacterial transformation is a process of horizontal gene transfer where bacteria take up naked DNA from their environment. The mechanism involves cell-free DNA from lysed bacteria being taken up by competent bacteria, where the single-stranded DNA integrates into the bacteria's genome. Transformation can be used for gene mapping by analyzing the frequency of co-transformation of marker genes, which is inversely proportional to the distance between genes. Bacteriophage transduction is another form of horizontal gene transfer where bacteriophage acts as a vector, transferring DNA from a donor bacterium to a recipient. Restriction enzymes were discovered as a bacterial defense mechanism against bacteriophage involving enzymes that cut DNA at specific recognition sequences.

1. By Dr. Sonia Goel
SGT University,
Gurugram

2.  Discovered in 1929 by Fridick Graffith.
 Bacterial transformation is a process of
horizontal gene transfer by which some
bacteria take up foreign genetic material
(naked DNA) from the environment.
 Mechanism :-
 1. Cell free transforming DNA in the
bacterium immediate environment can be
naturally released when cell die and lysis.

3.  2. Once DNA come in contact with
competent bacteria, linear dsDNA converted
by SsDNA and one strand is degraded.
 3. SsDNA exogonated is unstable and
degrade unless, they are integrated into
endogonate by homologus.

5.  Transformation is used for gene mapping.
 Genetics analysis of transformation is based on
principles that two marker gene transfer
together, of they are mean enough to be carried
on DNA fragments.
 Freq. Of co- transforamtion is inversely
proportional to the distance between the gene.
 Two type of transformation :-
 1. Natural
 2. Artificial

6.  It is a process in which bacteriophage
functions as a vector vehicle to transfer DNA
from donor bacterium to recipient bacteria.
 Discovered by :- Zinder and ledurberg in
salmonella typimurium 1951.
 It consists of Two type:-
 1. General Transduction. 2. Specialized.

7.  Two type :- 1. Temperate ( lambda page )
lysogenic cycle.
 2.Virulent ( T4 cell ) lytic cell.


8.  Generalized :- The bacteriophage can pick up
any portion of host genome.
 Lytic cycle
 Specialized :- The bacteriophage can pick up
specific portion of host genome.
 Lysogenic

10.  Restrictions enzyme were discovered due to
name and phenomena of host restrictions of
bacterial phage.
 Restrictions endonuclease are enzyme that
cut the DNA at specific site.
 The enzyme are found in bacteria and archea
provide a defence mechanism against
invading virus.
 Some bacteria defence themselves from
attack by bacteriophage by producing.

12.  The restrictions enzyme selectively cut up
foreign DNA in a process restriction
 There are 3 types of restrictions
endonuclease.
 Type 1 :- Recognition seq. Of about 15 bp
they cleave the DNA about 1000bp away from
5' end of seq. TCA located with recognition
site.
 Type 2 :- Restrictions mapping and gene
cloning.
 Type 3 :- Intermediate type 1 and type 2.

13. THANKYOU