Breif study of bacterial plasmid...... An extracellular organelle of cell

1. PLASMIDS
BY:
ASNAD KHAN
R.NO 19TH
TO:
SIR MUHAMMAD

2. HISTORY
The term Plasmid was
introduced in 1952 by the
American molecular
biologist Joshua Lederberg.
 They refer to "any
extrachromosomal hereditary
determinant”.

3. WHAT IS PLASMID?
 A Plasmid is a small DNA molecule
within a cell that is physically
separated from a chromosomal
DNA
 It can replicate independently.
 They are most commonly found as
small circular, double-stranded
DNA molecules in bacteria.

4. PLASMIDS
 They are found in numbers ranging
from one per cell to hundreds per
cell (this is called "copy number")
 Plasmids vary in size, but most are
between 1,000 to 25,000 base
pairs.
 It can be found in Bacteria and
Eukarya.
.

5. PLASMIDS
 Plasmids are not essential for the
survival of bacteria.
 But they may encode a wide
variety of genetic determinants,
which permit their bacterial hosts
to survive better in an adverse
environment or to compete
better with other microorganisms
occupying the same ecological
environment.

6.  PLASMID
MAP
 An origin of replication
 A selectable marker
gene (e.g. resistance to
ampicillin)
 A cloning site (a place
to insert foreign DNAs

7. Types of Plasmids
There are five main classes :
 Fertility- F-plasmids
They are capable of conjugation
(transfer of genetic material between
bacteria ).
 Resistance- R-plasmids
Which contain genes that can build a
resistance against antibiotics or heavy–
metal.

8.  Col-Plasmids
Which contain genes that code for
bacteriocins , that can kill other bacteria.
 Degradative Plasmids
Which enable the digestion of unusual
substances.
 Virulence Plasmids
Which turn the bacterium into a pathogen.

9. PLASMID EXCHANGE
Bacteria can exchange or
transfer plasmid between other
bacteria in three different ways.
In every case the source cells of
the plasmid are called donors
And the cells that receive the
plasmid are called the
recipients.

10. The three forms of bacterial DNA
exchange are :
1) CONJUGATION
This process involves
one bacterium making
a copy of a plasmid,
and transferring that
copy to another
bacterium.

11. 2) TRANSFORMATION
This is the process in
which a recipient cell
takes up plasmid DNA
from the environment
(such as DNA released
from a dead organism.

12. 3) TRANSDUCTION
This process
involves the transfer
of plasmid DNA
from one cell to
another by a
bacteriophage.

13. Conformations of Plasmids
Plasmid DNA may appear
in different conformations,
like, coiled, Supercoiled,
circular and linear, which
(for a given size) run at
different speeds in a gel
during electrophoresis:
Supercoiled

14. Plasmid DNA Extraction
•
•
•
 Plasmid DNA can easily be purified away from
the rest of the genome. For their use as
vectors and for molecular cloning .
 In recent times many commercial kits have
been created to perform plasmid extraction at
various scales . which are:
Minipreps
Medipreps
Maxipreps

15. Visualization of plasmid
Plasmid can be visualized on
a gel after staining with:
Ethidium Bromide
And viewing the
fluorescence pattern
under an ultraviolet light.

16. (-)
Large molecules
Small molecules
(+)
gel electrophoresis of plasmid

17. Applications of Plasmids
Plasmids are extremely valuable tools in the fields of
biology and genetics, specifically in the area of genetic
engineering where they are commonly used to multiply (make
many copies of ) particular genes .
Plasmids in this conditions are called vectors.

18. They play a critical role in :
 Gene Cloning
 Recombinant Protein Production
 (e.g., of human insulin).

19. Software For Bioinformatics And Design
 The use of plasmids as a technique
in molecular biology is supported
by bioinformatics software.
 These programs record
the DNA sequence of plasmid
vectors, help to predict cut sites
of restriction enzymes and to plan
manipulations.
 Examples of software packages
that handle plasmid maps are ApE.