MICROBIOLOGY PPT LECTURE NOTES | Karya Tulis Ilmiah
Chapter 4 bacteriophage
Bacteriophages ( phages ) are obli
gate intracellular parasites that mu
ltiply inside bacteria by making use
of some or all of the host biosynthe
tic machinery . They are viruses th
at infect bacteria.
Composition of Bacterioph
age
Nucleic acid: either DNA or RNA but n
ot both
ds DNA, ss RNA, ss DNA
unusual or modified bases
encode 3-5 gene products to over 100 g
ene products
Protein: function in infection and prot
ect the nucleic acid
Structure of Bacterioph
age
different sizes and shapes
icosahedra
l 二二二二
filamento
us
Capsid
DNA
Contractile
Sheath
Head
Tail
Tail Fibers
Base Plate
Types of Bacteriophage
Lytic or Virulent Phages
毒毒毒毒毒
Lysogenic or Temperate Phage
毒毒毒毒毒毒毒毒毒毒毒毒
Lytic or Virulent Phages
Definition:
Lytic or virulent phages are p
hages which can only multiply in b
acteria and kill the cell by lysis at t
he end of the life cycle.
Life Cycle
Adsorption 毒毒
Penetration 毒毒
Biological Synthesis 毒毒毒毒
Maturation and Release 毒毒毒毒毒
Adsorption 毒毒
Penetration 毒毒
Biological Synthesis 毒毒毒毒
Maturation and Release 毒毒毒毒毒
Bacteriophage bin
ding to and injecti
ng their DNA into
a bacterial cell
bacteriophage aft
er contraction of
sheath
normal bacteriopha
ge
Assay for Lytic Phag
e
Plaque assay 二二二二
Lytic phage are enumerated by a pl
aque assay. A plaque is a clear are
a which results from the lysis of ba
cteria. Each plaque arises from a si
ngle infectious phage. The infectio
us particle that gives rise to a plaq
ue is called a pfu (plaque forming u
nit).
Lysogenic or Temperate Phage
毒毒毒毒毒毒毒毒毒毒毒毒
Lysogenic or temperate phages are those that ca
n either multiply via the lytic cycle or enter a quiesc
ent state in the cell. In this quiescent state most of t
he phage genes are not transcribed; the phage geno
me exists in a repressed state. The phage DNA in thi
s repressed state is called a prophage because it is n
ot a phage but it has the potential to produce phage.
In most cases the phage DNA actually integrates int
o the host chromosome and is replicated along with
the host chromosome and passed on to the daughte
r cells. The cell harboring a prophage is termed a lys
ogenic bacterium.
Lysogenic bacterium
Induction
Animation summarizing the
lysogenic
life cycle of a temperate
bacteriophage.
二二二二二二二二二二二二二二二二二
lysogenic conversion
二二二二二
When a cell becomes lysogenized,
occasionally extra genes carried by
the phage get expressed in the cell
. These genes can change the prop
erties of the bacterial cell. This pro
cess is called lysogenic conversion.
Application of Bacterioph
age
Used in treatment of bacterial infec
tions
Used for the identification of patho
genic bacteria (phage typing 二二二二
二二 )
Used in molecular biology
Bacteriophages ( phages ) are obli
gate intracellular parasites that mu
ltiply inside bacteria by making use
of some or all of the host biosynthe
tic machinery . They are viruses th
at infect bacteria.
Composition of Bacterioph
age
Nucleic acid: either DNA or RNA but n
ot both
ds DNA, ss RNA, ss DNA
unusual or modified bases
encode 3-5 gene products to over 100 g
ene products
Protein: function in infection and prot
ect the nucleic acid
Structure of Bacterioph
age
different sizes and shapes
icosahedra
l 二二二二
filamento
us
Capsid
DNA
Contractile
Sheath
Head
Tail
Tail Fibers
Base Plate
Types of Bacteriophage
Lytic or Virulent Phages
毒毒毒毒毒
Lysogenic or Temperate Phage
毒毒毒毒毒毒毒毒毒毒毒毒
Lytic or Virulent Phages
Definition:
Lytic or virulent phages are p
hages which can only multiply in b
acteria and kill the cell by lysis at t
he end of the life cycle.
Life Cycle
Adsorption 毒毒
Penetration 毒毒
Biological Synthesis 毒毒毒毒
Maturation and Release 毒毒毒毒毒
Adsorption 毒毒
Penetration 毒毒
Biological Synthesis 毒毒毒毒
Maturation and Release 毒毒毒毒毒
Bacteriophage bin
ding to and injecti
ng their DNA into
a bacterial cell
bacteriophage aft
er contraction of
sheath
normal bacteriopha
ge
Assay for Lytic Phag
e
Plaque assay 二二二二
Lytic phage are enumerated by a pl
aque assay. A plaque is a clear are
a which results from the lysis of ba
cteria. Each plaque arises from a si
ngle infectious phage. The infectio
us particle that gives rise to a plaq
ue is called a pfu (plaque forming u
nit).
Lysogenic or Temperate Phage
毒毒毒毒毒毒毒毒毒毒毒毒
Lysogenic or temperate phages are those that ca
n either multiply via the lytic cycle or enter a quiesc
ent state in the cell. In this quiescent state most of t
he phage genes are not transcribed; the phage geno
me exists in a repressed state. The phage DNA in thi
s repressed state is called a prophage because it is n
ot a phage but it has the potential to produce phage.
In most cases the phage DNA actually integrates int
o the host chromosome and is replicated along with
the host chromosome and passed on to the daughte
r cells. The cell harboring a prophage is termed a lys
ogenic bacterium.
Lysogenic bacterium
Induction
Animation summarizing the
lysogenic
life cycle of a temperate
bacteriophage.
二二二二二二二二二二二二二二二二二
lysogenic conversion
二二二二二
When a cell becomes lysogenized,
occasionally extra genes carried by
the phage get expressed in the cell
. These genes can change the prop
erties of the bacterial cell. This pro
cess is called lysogenic conversion.
Application of Bacterioph
age
Used in treatment of bacterial infec
tions
Used for the identification of patho
genic bacteria (phage typing 二二二二
二二 )
Used in molecular biology