Microbial Genetics: Transformation, Transduction, Conjugation, Plasmids, Transposons

1. Microbial Genetics
16 July 2021 Abhijit Debnath BP605T and Biotech Unit-1 1
CO1.1
Noida Institute of Engineering and Technology
(Pharmacy Institute) Greater Noida
Abhijit Debnath
Asst. Professor
NIET, Pharmacy
Institute
Unit: 4
Subject Name: Biotechnology
(BP605T)
Course Details
(B. Pharm 6th Sem)

2. Microbial
Genetics
16 July 2021 Abhijit Debnath BP605T and Biotech Unit-1 2
 Transformation
 Transduction
 Conjugation
 Plasmids
 Transposons
CO1.1
Noida Institute of Engineering and Technology
(Pharmacy Institute) Greater Noida

3.  Amplification of specific regions of DNA also can be achieved with bacterial enzymes using the polymerase chain reaction (PCR) or
other enzyme- based methods of nucleic acid amplification (e.g. transcription-mediated amplification).
 The introduction of foreign DNA or RNA into bacteria or eukaryotic cells is a common technique in molecular biology There are
multiple ways foreign DNA can be introduced into cells including transformation, transduction, conjugation, and transfection.
 Transformation, transduction, and conjugation occur in nature as forms of Horizontal gene transfer, but transfection is unique to the
lab.
MICROBIAL GENETICS CO4.2
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4.  Transformation is the uptake of genetic material from the environment by bacterial cells.
 In nature, this genetic material often comes from adjacent lysed bacteria and can include plasmid DNA or fragmented DNA released
into the environment.
 Various factors promote natural transformation in different bacteria such as growth phase of the cells or the presence of specific
substances.
TRANSFORMATION CO4.2
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 Though not all bacteria are naturally competent to take up DNA,
they can be made competent through chemical manipulation in
the lab.
 This is commonly done using calcium chloride which
permeabilizes the cell membrane so the bacteria can easily
uptake your plasmid of interest.
 Scientists can also use electroporation, the application of an
electrical charge to cells, to increase cell membrane permeability
and thus transformation efficiency.

5.  Transduction is the process by which a virus transfers genetic material from one bacterium to another.
 Viruses called bacteriophages are able to infect bacterial cells and use them as hosts to make more viruses.
 After multiplying, these viruses assemble and occasionally remove a portion of the host cell's bacterial DNA.
 Later, when one of these bacteriophages infects a new host cell, this piece of bacterial DNA may be incorporated into the genome
of the new host..
TRANSDUCTION CO4.2
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 There are two types of transduction: generalized and specialized.
 In generalized transduction, the bacteriophages can pick up any
portion of the host's genome.
 In specialized transduction, the bacteriophages pick up only specific
portions of the host's DNA. Scientists have taken advantage of the
transduction process to stably introduce genes of interest into
various host cells using viruses.

6.  Transduction is a common tool used by scientists to introduce different DNA sequences of interest into a bacterial cell or a host’s
genome.
 To do this scientists commonly use phagemids, a DNA cloning vector that contains both bacteriophage and plasmid properties.
 The phagemids are packaged into replication-incompetent phage particles with assistance from a ‘helper’ phage prior to
transduction.
 Scientists also use transduction to introduce foreign DNA into eukaryotic cells, like mammalian cell lines.
 This can be done with lentiviral and Adeno Associated Viruses (AAV). Lentiviral and AAV can be used to create both transient cell
lines, where a gene of interest is expressed but not integrated into the genome and stable cell lines, where foreign DNA is
incorporated into the cell’s genome and is thus passed down through cell division.
 All kinds of different lentiviral and AAV plasmids as well as ready-to-use viral preparations at Addgene.
TRANSDUCTION CO4.2
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7.  Conjugation is the process by which one bacterium transfers genetic material to
another through direct contact.
 During conjugation, one bacterium serves as the donor of the genetic material,
and the other serves as the recipient.
 The donor bacterium carries a DNA sequence called the fertility factor, or F-factor.
 The F-factor allows the donor to produce a thin, tubelike structure called a pilus,
which the donor uses to contact the recipient.
 The pilus then draws the two bacteria together, at which time the donor
bacterium transfers genetic material to the recipient bacterium.
 Typically, the genetic material is in the form of a plasmid, or a small, circular piece
of DNA.
 The genetic material transferred during conjugation often provides the recipient
bacterium with some sort of genetic advantage. For instance, in many cases,
conjugation serves to transfer plasmids that carry antibiotic resistance genes.
CONJUGATION CO4.2
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8. www.themegallery.com
 A plasmid is a small, circular, double-stranded DNA molecule that is distinct from a
cell's chromosomal DNA.
 Plasmids naturally exist in bacterial cells, and they also occur in some eukaryotes.
Often, the genes carried in plasmids provide bacteria with genetic advantages, such
as antibiotic resistance.
 Plasmids have a wide range of lengths, from roughly one thousand DNA base pairs
to hundreds of thousands of base pairs.
 When a bacterium divides, all of the plasmids contained within the cell are copied
such that each daughter cell receives a copy of each plasmid.
 Bacteria can also transfer plasmids to one another through a process called
conjugation.
PLASMIDS CO4.2
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9. www.themegallery.com
 Transposon, class of genetic elements that can “jump” to different locations within a genome. Although these elements are frequently
called “jumping genes,” they are always maintained in an integrated site in the genome.
 Transposons may be found as part of a bacterium's nucleoid or in plasmids and are usually between one and twelve genes long.
 A transposon contains a number of genes, coding for antibiotic resistance or other traits, flanked at both ends by insertion sequences
coding for an enzyme called transpoase. Transpoase is the enzyme that catalyzes the cutting & resealing of the DNA during transposition.
 Thus, such transposons are able to cut themselves out of a bacterial nucleoid or a plasmid and insert themselves into another nucleoid
or plasmid and contribute in the transmission of antibiotic resistance among a population of bacteria.
TRANSPOSON CO4.2
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