The document discusses plasmids, which are small DNA molecules found in bacteria that can replicate independently of the bacterial chromosome. Plasmids contain genes and can be transferred between bacteria. They have various functions like carrying antibiotic resistance genes or virulence genes. Plasmids are commonly used as cloning vectors in genetic engineering to make copies of genes and produce proteins of interest.

1. PLASMIDPLASMID

2. The term plasmid was first introduced by the American molecular
biologist Joshua Lederberg in 1952.
He was an American molecular biologist known for his work in
genetics, artificial intelligence, and space exploration
He won the 1958 Nobel Prize in Physiology or Medicine for
discovering that bacteria can mate and exchange genes. He shared
the prize with Edward L. Tatum and George Beadle who won for their
work with genetics.

3. WHATWHAT ISIS PLASMIDPLASMID ??
• Like other organisms, bacteria use double-
stranded DNA as their genetic material.
However, bacteria organize their DNA differently
to more complex organisms.
• In addition to the chromosome, bacteria often
contain plasmids – extra -chromosomal
hereditary determinant

4. • Plasmids are small double-stranded DNA molecules,
usually circularthat can exist independently of host
chromosomes and are present in many bacteria (they are
also present in some yeasts and other fungi).
• They have their own replicationorigins and are
autonomously replicating and stably inherited .
• A repliconis a DNA molecule or sequence that has a
replication origin and is capable of being replicated.
Plasmids and bacterial chromosomes are separate
replicons.
• Plasmids have relatively few genes, generally less than 30.
Their genetic information is not essential to the host, and
bacteria that lack them usually function normally.

5. TYPESTYPES OFOF PLASMIDSPLASMIDS
1.1.onon thethe basisbasis ofof functionfunction
• Fertility Plasmids ( F PLASMID )
– carry the fertility genes (tra-genes) for
conjugation, the transfer of genetic information
between two cells.
• Resistance Plasmids (R PLASMID )
– Contain genes that can build resistance to
antibiotics or poisons.
• Col Plasmids
– contain genes that encode for the antibacterial
polypeptides called bacteriocins, a protein that
kills other strains of bacteria. The col proteins of
E. co li are encoded by proteins such as Col E1.

6. • Degradative Plasmids
– Allows to digest unusual substances.
• Virulence Plasmids
– Turn bacterium into a pathogen
• EPISOMES
an episome is a plasmid of bacteria or viral DNA that can
integrate itself into the chromosomal DNA of the host
organism . For this reason, it can stay intact for a long
time, be duplicated with every cell division of the host,
and become a basic part of its genetic makeup.

7. 2.BY THEIR ABILITY TO TRANSFER
TO
OTHER BACTERIA
Conjugative plasmids
contain ‘tra’ genes (genes necessary for non-sexual transfer of genetic
material), which perform the complex process of conjugation, the
transfer of plasmids to another bacterium.
• Non-conjugative plasmids
are incapable of initiating conjugation, hence they can only be
transferred with the assistance of conjugative plasmids.
• Intermediate classes of plasmids
are mobilizable, and carry only a subset of the genes required for
transfer. They can parasitize a conjugative plasmid, transferring at
high frequency only in its presence. Plasmids are now being used to
manipulate DNA and may possibly be a tool for curing many
diseases.

8. PLASMIDPLASMID
CONSISTS OF :
An origin of replication .
Multiple cloning sites( a
polylinker to clone the gene
of interest) .
An antibiotic resistance
gene ( Selectable marker).
The size of plasmids varies
from 1 to over 400 kilobase
pairs (kbp).

9. PlasmidPlasmid – a– a vectorvector
A vector is a DNA molecule used to carry genes
from organism to organism.
Plasmids have 3 key parts. They have an origin
of replication, a selectable marker gene, and a
cloning site. The origin of replication is used to
indicate where DNA replication is to begin. The
selectable marker gene is used to distinguish cells
containing the plasmid from cells that ’ containȵɀȿ Ʌ
it. The cloning site is a site in the plasmid where the
DNA is inserted.

11. • Plasmids are first type of cloning
vectordeveloped.These are used as
vector to clone DNA in bacteria.
Engineered plasmids can be used to
clone genetic material of up to 10,000
base pairs.
• Examples :
 pBR322 plasmid
 pUC18 plasmid

14. PlasmidsPlasmids inin geneticgenetic
engineeringengineering
• In genetic engineering, plasmids provides a
versatile tool that are used to make copies
of particular genes. This is done by
inserting the gene to be replicated into the
plasmid, then inserting the plasmids into
bacteria by a process called
“Transformation”.
• Next the bacteria are exposed to antibiotics
that destroy bacteria without the plasmid.
These bacteria are then grown in large

16. Various applications

17. DNADNA VACCINESVACCINES
• Plasmid DNA (pDNA) is the base for promising DNA
vaccines and gene therapies against many infectious,
acquired, and genetic diseases, including HIV-AIDS,
Malaria, and different types of cancer, enteric
pathogens, and influenza.
• Compared to conventional vaccines, DNA vaccines
have many advantages such as high stability, not
being infectious, focusing the immune response to
only those antigens desired for immunization and
long-term persistence of the vaccine protection.
• Especially in developing countries, where
conventional effective vaccines are often unavailable
or too expensive, there is a need for both new and
improved vaccines. Therefore the demand of pDNA is
expected to rise significantly in the near future.

18. RReferenceseferences
• Lancing M. Prescott – Microbiology
• http://www.innovateus.net
• http://www.ncbi.nlm.nih.gov/
• https://www.newworldencyclopedia.org
• Structural biochemistry .docx plasmid

19. Thank you !!