Viruses like bacteriophages can multiply within host bacteria through two cycles:
1) The lytic cycle directly leads to host cell lysis and death as new virions are assembled and released.
2) The lysogenic cycle allows the phage DNA to integrate into the host chromosome and remain latent without killing the cell. During cell division, the prophage DNA is replicated along with the host DNA.
VIRUS PHARMACEUTICAL MICROBIOLOGY (BP303T)Unit-IIIPart-2Study of morphology, ...Ms. Pooja Bhandare
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PHARMACEUTICAL MICROBIOLOGY (BP303T)Unit-IIIPart-2Study of morphology, classification, reproduction/replication and cultivation of Virus. Introduction, Def General characteristics of Viruses: small size characteristic shapes, obligate intracellular parasites no built-in metabolic machinery no ribosomes
only one type of nucleic acid
do not grow in size. Morphology of Virus: Helical, Polyhedral (Icosahedral) Viral Envelop, Complex virus, Classification of virus. Viral Replication LIFE CYCLE OF BACTIRIOPHAGES Lytic cycle: Attachment, Penetration, Biosynthesis, Maturation and Release of progeny Phage Particles. The Lysogenic Cycle, Cultivation of virus : Animal inoculation, Embryonated eggs or chick embryo method and Tissue culture or cell culture: Organ cultures Explant culture and Cell culture. Types of cell culture
1.Primary cell culture: 2. Diploid cell culture (Semi-continuous cell lines):3. Heteroploid cultures (Continuous cell lines):
MULTIPLICATION OF HUMAN VIRUS:1. Attachment of Viral Particles 2. Penetration 3. Uncoating 4. Replication Of Viral Nucleic Acids And Translation Of The Genome 5) Maturation Or Assembly Of Virions. ) 6. Release Of Virions Into The Surrounding Environment
introduction of bacteriophage , discovery, morphology, structure and life cycle of bacteriophage,
imp. of bacteriophage and other briefly define lytic and lysogenic cycle.
VIRUS PHARMACEUTICAL MICROBIOLOGY (BP303T)Unit-IIIPart-2Study of morphology, ...Ms. Pooja Bhandare
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PHARMACEUTICAL MICROBIOLOGY (BP303T)Unit-IIIPart-2Study of morphology, classification, reproduction/replication and cultivation of Virus. Introduction, Def General characteristics of Viruses: small size characteristic shapes, obligate intracellular parasites no built-in metabolic machinery no ribosomes
only one type of nucleic acid
do not grow in size. Morphology of Virus: Helical, Polyhedral (Icosahedral) Viral Envelop, Complex virus, Classification of virus. Viral Replication LIFE CYCLE OF BACTIRIOPHAGES Lytic cycle: Attachment, Penetration, Biosynthesis, Maturation and Release of progeny Phage Particles. The Lysogenic Cycle, Cultivation of virus : Animal inoculation, Embryonated eggs or chick embryo method and Tissue culture or cell culture: Organ cultures Explant culture and Cell culture. Types of cell culture
1.Primary cell culture: 2. Diploid cell culture (Semi-continuous cell lines):3. Heteroploid cultures (Continuous cell lines):
MULTIPLICATION OF HUMAN VIRUS:1. Attachment of Viral Particles 2. Penetration 3. Uncoating 4. Replication Of Viral Nucleic Acids And Translation Of The Genome 5) Maturation Or Assembly Of Virions. ) 6. Release Of Virions Into The Surrounding Environment
introduction of bacteriophage , discovery, morphology, structure and life cycle of bacteriophage,
imp. of bacteriophage and other briefly define lytic and lysogenic cycle.
Viruses that infect bacteria.
Occur widely in nature in close association with bacteria.
Readily isolated from faeces, sewage and other natural sources.
Tadpole shaped, with hexagonal head and a cylindrical tail.
Head consists of a tightly packed core of ds DNA surrounded by a protein coat or capsid.
The tail composed of a contractile sheath surrounding the hollow core
Terminal base plate having prongs or tail fibres attached.
Viruses that infect bacteria.
Occur widely in nature in close association with bacteria.
Readily isolated from faeces, sewage and other natural sources.
Tadpole shaped, with hexagonal head and a cylindrical tail.
Head consists of a tightly packed core of ds DNA surrounded by a protein coat or capsid.
The tail composed of a contractile sheath surrounding the hollow core
Terminal base plate having prongs or tail fibres attached.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
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Francesca Gottschalk from the OECDâs Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Honest Reviews of Tim Han LMA Course Program.pptxtimhan337
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Personal development courses are widely available today, with each one promising life-changing outcomes. Tim Hanâs Life Mastery Achievers (LMA) Course has drawn a lot of interest. In addition to offering my frank assessment of Success Insiderâs LMA Course, this piece examines the courseâs effects via a variety of Tim Han LMA course reviews and Success Insider comments.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
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Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
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In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
How to Make a Field invisible in Odoo 17Celine George
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It is possible to hide or invisible some fields in odoo. Commonly using âinvisibleâ attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Safalta Digital marketing institute in Noida, provide complete applications that encompass a huge range of virtual advertising and marketing additives, which includes search engine optimization, virtual communication advertising, pay-per-click on marketing, content material advertising, internet analytics, and greater. These university courses are designed for students who possess a comprehensive understanding of virtual marketing strategies and attributes.Safalta Digital Marketing Institute in Noida is a first choice for young individuals or students who are looking to start their careers in the field of digital advertising. The institute gives specialized courses designed and certification.
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2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
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http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasnât one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
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This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
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Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
⢠The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
⢠The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate âany matterâ at âany timeâ under House Rule X.
⢠The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
2. Teaching and learning methods: Lectures, visual aid, interactive forms,
questions- answer session and group discussion.
At end of the lecture student should be able to answer the following
questions:
⢠Explain the one step growth curve of virus.
⢠Summarize how virus multiply using lytic cycle.
⢠Define lysogenic cycle. Compare lytic and lysogenic cycle.
Reference books:
1. Microbiology: An Introduction, 12th edition- Tortora GJ & Funke BR, Chapter
Thirteen; Page: 369
3. Multiplication of Bacteriophages
⢠Although the means by which a virus enters and exits a host cell
may vary, the basic mechanism of viral multiplication is similar for
all viruses. The best understood viral life cycles are those of the
bacteriophages. Phages can multiply by two alternative
mechanisms: the lytic cycle or the lysogenic cycle.
⢠The lytic cycle ends with the lysis and death of the host cell,
whereas the host cell remains alive in the lysogenic cycle. The T-
even bacteriophages (T2, T4, and T6) have been studied most
extensively; we will describe the multiplication of T-even
bacteriophages in their host, E. coli, as an example of the lytic
cycle.
4. Multiplication & one-step growth curve of bacteriophage
One Step Growth Curve:
⢠The growth response during virus replication is
illustrated in the figure. The response takes the
form of a one-step growth curve. This is so named
because a time course of virion numbers in the
culture medium shows essentially no increase
during the replication cycle until cells burst and
release their newly synthesized virions.
⢠Following adsorption, infectious virions cannot be
detected in the growth medium, a phenomenon
called eclipse.
⢠During the latent period, which includes the
eclipse and early maturation phases, viral nucleic
acid replicates and protein synthesis occurs.
⢠During the maturation period, virus nucleic acid
and protein are assembled into mature virions
and then released.
5. The Lytic Cycle
⢠The virions of T-even bacteriophages are large, complex, and nonenveloped,
with a characteristic head and tail structure. The length of DNA contained in
these bacteriophages is only about 6% of that contained in E. coli, yet the
phage has enough DNA for over 100 genes. The multiplication cycle of these
phages, like that of all viruses, occurs in five distinct stages: attachment,
penetration, biosynthesis, maturation, and release.
1. Attachment
⢠After a chance collision between phage particles and bacteria, attachment, or
adsorption, occurs. During this process, an attachment site on the virus
attaches to a complementary receptor site on the bacterial cell. This
attachment is a chemical interaction in which weak bonds are formed
between the attachment and receptor sites. T-even bacteriophages use fibers
at the end of the tail as attachment sites. The complementary receptor sites
are on the bacterial cell wall.
6. The Lytic Cycle
2. Penetration:
⢠After attachment, the T-even bacteriophage injects its DNA into the
bacterium. To do this, the bacteriophageâs tail releases phage lysozyme, which
breaks down a portion of the bacterial cell wall. During the process of
penetration, the tail sheath of the phage contracts and the tail core is driven
through the cell wall. When the tip of the core reaches the plasma membrane,
the DNA from the bacteriophageâs head passes through the tail core, through
the plasma membrane, and enters the bacterial cell. The capsid remains
outside the bacterial cell. Therefore, the phage particle functions like a
hypodermic syringe to inject its DNA into the bacterial cell.
7.
8. 3. Biosynthesis:
⢠Once the bacteriophage DNA has reached the cytoplasm of the host cell, the
biosynthesis of viral nucleic acid and protein occurs. Host protein synthesis is
stopped by virus-induced degradation of the host DNA, viral proteins that interfere
with transcription, or the repression of translation.
⢠Initially, the phage uses the host cellâs nucleotides and several of its enzymes to
synthesize many copies of phage DNA. Soon after, the biosynthesis of viral proteins
begins. Any RNA transcribed in the cell is mRNA transcribed from phage DNA for the
biosynthesis of phage enzymes and capsid proteins. The host cellâs ribosomes,
enzymes, and amino acids are used for translation. Genetic controls regulate when
different regions of phage DNA are transcribed into mRNA during the multiplication
cycle. For example, early messages are translated into early phage proteins, the
enzymes used in the synthesis of phage DNA. Also, late messages are translated into
late phage proteins for the synthesis of capsid proteins. For several minutes following
infection, complete phages cannot be found in the host cell. Only separate
components DNA and protein can be detected. The period during viral multiplication
when complete, infective virions are not yet present is called the eclipse period.
The Lytic Cycle
9. 4. Maturation:
⢠In the next sequence of events, maturation occurs. In this process,
bacteriophage DNA and capsids are assembled into complete virions. The
viral components essentially assemble into a viral particle spontaneously,
eliminating the need for many non-structural genes and gene products. The
phage heads and tails are separately assembled from protein subunits, and
the head is filled with phage DNA and attached to the tail
5. Release:
⢠The final stage of viral multiplication is the release of virions from the host
cell. The term lysis generally used for this stage in the multiplication of T-
even phages because in this case, the plasma membrane actually breaks open
(lysis). Lysozyme, which is coded for by a phage gene, is synthesized within
the cell. This enzyme causes the bacterial cell wall to break down, and the
newly produced bacteriophages are released by the host cell. The released
phages infect other susceptible cells in the vicinity, and the viral multiplication
cycle is replaced within those cells.
The Lytic Cycle
10. Bacteriophage Lambda (l): The lysogenic cycle:
⢠In contrast to T-even bacteriophages, some viruses do not cause
lysis and death of the host cell when they multiply. Some phages
can either proceed through a lytic cycle or begin a lysogenic cycle
by incorporating their DNA into the host cell's DNA. In the latter
state, called lysogeny, the phage remains latent (inactive). Phages
that can multiply by either mechanism are called lysogenic phages
or temperate phages. The participating bacterial host cells are
known as lysogenic cells.
⢠We will use the bacteriophage l (lambda), a well-studied
temperate phage, as an example of the lysogenic cycle.
12. (1) l-phage penetrates into an E. coli cell,
(2) The originally linear phage DNA forms a circle,
(3A) this circle can multiply and be transcribed,
(3B) alternatively, the circle can recombine with and become part of the circular
bacterial DNA (the lysogenic cycle). The inserted phage DNA is now a prophage. Most of
the prophage genes are repressed by two repressor proteins produced by the phage
genes. These repressors bind operator and stop transcription of all the other phage
genes. Thus, the phage genes that would otherwise direct the synthesis and release of
new virions are turned off, in much the same way that the genes of the E. coli lac
operon are turned off by the lac repressor. Every time the host cell's machinery
replicates bacterial chromosome,
(4A) leading to the production of new phage and to cell lysis (the lytic cycle).
(4B) it also replicates the prophage DNA. The prophage remains latent within the
progeny cells.
(5) However, a rare spontaneous event, or action of UV light or certain chemicals, can
lead to excision (popping-out) of the phage DNA, and to initiation of the lytic cycle.