DNA transformation is a process that explain how the DNA transfers in the organism.

1. University of allahabad
Department of Botany
Submitted to-
Dr.Pradeep Kumar Yadav
Dr.Ritu Mishra.
Submitted by-
Neetu Dubey
M.Sc III Semester

2. DNA Transformation
• Transformation was the first horizontal gene - transfer
discovered in bacteria.
• It was discoverd by Fred Griffith in 1928.
• Transformation is the uptake of a naked DNA molecule or
fragment from the surrounding environment by a cell and the
incorporation of this molecule into the chromosome of the
recipient.

3. Type of Transformation
1. Natural
2. Artificial.
• Natural transformation is very rare event and has been observed
in both gram- positive(e.g.,Streptococcus pneumoniae, Bacillus
subtilis) as well as gram – negative bacteria ( e.g.,Haemophilus
influenzae).
• Transformation in Haemophilus influenzae (the first gram –
negative bacterium in which natural competance was found) and
some other gram- negative bacteria are different from that in
gram- positive bacteria like Streptococcus.

4. Competence
• The ability of recipient bacterium to take up DNA molecules from
the surrounding environment and become transformed is known
as competence.
• Competence is an inheritable characteristics.
• Competent bacteria that can take up DNA, encode proteins
called competence factors.
• These protein facilitate the binding of DNA fragments to the cell
surface and uptake of DNA into the cytoplasm.

5. Gram – positive
Bacteria
• Streptococcus pneumoniae becomes
competent during exponential growth
phase.
• Competent bacterial cells binds ds
DNA fragments.
• The uptake of DNA into cytoplasm is
random and any portion of the donor’s
may be entered.
• During uptake one strand is hydrolysed
by a membrane- associated
exonuclease,the other strand move in
the cytoplasm.
• Streptococcus pneumoniae and
Bacillus subtilis can not discriminate
their own and foreign DNA.

6. Gram - negative
bacteria
• In Haemophilus influenzae, DNA
uptake is associated with the
formation of small membranous
structures,called
transformasomes,which protrude
outside the cell.
• The transforming DNA is taken into
these vesicles where is then
internalized into the cell .
• DNA from only closely related species
can enter into the cytoplasm.

7. Griffith experiment

8. Process of Transformation

9. • DNA is released into the environment by bacterial cell lysis.
• Naturally competent bacteria pull DNA fragments.
• One strand enter into the cytoplasm with its 3’ end.
• Recipient cells that undergo this process and acquire a new
phenotype as are said to be transformed.
• dsDNA Passed to the DNA receptor ComEA before transfer to
EndA nuclease.
• EndA degrades one strand.
• ssDNA transferred via ComEC pore.

10. Reference
• Gerad.J.Tortora,Berdel.R.Funek,Christine.L.Case ,Microbiology An
introduction 6th edition.
• Pranav Kumar,Usha Mina ,life sciences,fundamental and practice
,8th edition.