The lysogenic cycle is a method by which a virus can replicate its dna using a host cell. Bacteriophage, also called phage or bacterial virus, any of a group of viruses that infect bacteria. The prophage may be converted into a virulent vegetative lytic phase spontaneously or by physical and chemical agents uv rays, h 2 0 2, nitrogen mustard. Lytic and lysogenic cycles are bacteriophage replication cycles, bacterial cells are lysed to release the viral particles in lytic cycle.
Include the term prophage or provirus in your answer. Complete nucleotide sequence of bacteriophage t7 dna and the locations of t7 genetic elements. When a temperate bacteriophage infects a bacterium, it can either replicate by means of the lytic life cycle and cause lysis of the host bacterium, or, it can incorporate its dna into the bacteriums dna and become a noninfectious prophage see figure 1. Lysogenic cells are immune to infection by same virus 2. The role of phage lysozyme in the life cycle of phage t4. In the lysogenic cycle, the virus inserts its dna into its host cells dna so that it will be copied when the cell divides. The key difference between lytic and lysogenic cycle of bacteriophage is that during lytic cycle of bacteriophage reproduction, the bacteriophage that enters the host cell present as a separate component without integrating with the host dna while in lysogenic cycle the bacteriophage dna is integrated into the host dna and replicate accordingly a. Lytic cycle the lytic is the viral reproductive cycle in which a virus takes over all metabolic activities of a cell. You will receive your score and answers at the end.
This dissociation is called induction and lytic cycle is followed releasing mature lysogenic phages. Lysogenic cycle bacteriophage l lysogeny incorporation into host dna latent period in animal cells trigger stimulates cell to enter lytic cycle 3 important results 1. In the lysogenic cycle, the virus reproduces by first injecting its genetic material, indicated by the red line, into the host cells genetic instructions. That is, a decision between a lytic cycle and a lysogenic cycle. Bacteriophage lytic and lysogenic cycle biology exams 4 u. The mechanism and the evolution of lysogenic cycle are much.
Bacteriophage phage are obligate intracellular parasites that multiply inside bacteria by making use of some or all of the host biosynthetic machinery i. Lyticlysogeny decision bacteriophage ecology group. While they are different, they can be interchangeable or the replication can involve both methods in separate phases. While the lytic cycle is common to both animal viruses and bacterial phages, the lysogenic cycle is more commonly found in animal viruses. Bacteriophage therapy has drawn the attention of researchers, due to their host specificity and selfreplicating, effeciently economical, and ecofriendly properties. Bacteriophages that only use the lytic cycle are called virulent phages in contrast to temperate phages. The lambda infected bacterium then exhibits either a lytic cycle or a lysogenic cycle. The lytic cycle results in the destruction of the infected cell and its membrane. Viruses are species specific, but almost every species on earth can be affected by some form of virus. A phage life cycle over the entirety of which the phage exists as a prophage. Download file pdf lytic cycle answers lytic cycle answers viruses updated explore the lytic and lysogenic viral replication cycles with the amoeba sisters.
The regulatory mechanisms underlying the lyticlysogeny decision can be described as giving rise to a bistable. Cleavage of the bacteriophage p1 packaging site pac is regulated. Difference between lytic and lysogenic cycle of bacteriophage. In the lysogenic cycle, bacteriophages reproduce without killing the host. The process of a phage infecting a bacterium and producing progeny is referred to as a lytic infection. Bacteriophages were discovered independently by frederick w. Lambda consists of two types of life cycles, the lytic and lysogenic. There are few phages called temperate phages that possess a unique ability to induce lysogenic cycle from the lytic cycle in some particular situations.
Occasionally, integrated viral genome detaches and released into the bacterial cytoplasm. Lysogenic or temperate phages are those that can either multiply via the lytic cycle or enter a dormant state in the cell. In the lysogenic cycle, phage nucleic acid will integrate into the bacterial genome. Reproduction of viruses the structure of viruses allows them to succeed in their main mission reproduction. Electron microscopy revealed that phage ma1 belongs to myoviridae family. A discussion of the properties of the phage in the lysogenic condition will follow, based on published data and on some unpublished results. In most cases the phage dna actually integrates into the host chromosome and is replicated along with the host chromosome and passed on to the daughter cells. They then destroy, or lyse, the cell, releasing new phage particles. Difference between lytic and lysogenic cycle of bacteriophage this video explains the difference between lytic and lysogenic cycle of bacteriophage summary of lytic and lysogenic cycle. Life cycles of bacteriophages life cycles, lytic virulent or lysogenic temperate. Broadly, the replication cycle of a bacteriophage could be of two typeslytic or lysogenic.
Lytic cycle medical visualisation of the bacteriophage. Lytic phages take over the machinery of the cell to make phage components. Learn vocabulary, terms, and more with flashcards, games, and other study tools. C can a bacteriophage in the lysogenic cycle switch to a. In general the life cycle of most phages at 37c varies between 22 and 60 minutes. Now customize the name of a clipboard to store your clips. Can a bacteriophage in the lysogenic cycle switch to a lytic cycle. During the bacteriophage lysogenic cycle free pdf ebooks. In the lysogenic cycle, the dna is only replicated, not translated into proteins. The life cycle of a lysogenic bacteriophage is illustrated below. Lysogenic signifies that prophages are capable of generating active phages that lyse their host cells. Temperate bacteriophage life cycle free pdf ebooks. Thus, bacteriophage can be viewed as model systems for animal cell viruses. In lytic cycle the subsequent steps are synthesis of phage components, assembly, maturation and release.
A bacteriophage ma1 with moderate host range was isolated from waste water. The lysogenic cycle is complementary to the lytic cycle for viral entry and reproduction within cells. Clipping is a handy way to collect important slides you want to go back to later. Lysogenic cycle definition and steps biology dictionary. Lytic and lysogenic cycles are two different methods of viral replication.
In the lytic cycle, the virus reproduces itself using the host cells machinery. Post genome uptake into a now phageinfected bacterium, a temperate phage must literally choose between displaying two distinct life styles. It is important to view temperate phages as heterogeneous populations as not all temperate phages enter the lysogenic cycle upon infection. Lysogenic cycles begin with phage reduction to a prophage and end that is, have completed one cycle with completion of prophage replication. Lysis of bacterial cell envelope and release of progeny phage. Studies of phage and host nucleic acid production in the nonpermissive host demonstrated that normal. The lysogenic cycle of a temperate bacteriophage such as lambda. The bacteriophage lambda is a virus that is parasitic in bacteria, attaching by its tail to the surface to the surface of an li cell and injecting its chromosome into the bacterium to multiply. Even though the viral nucleic acid becomes part of the host cells chromosome, it does not seem to affect. Here, the bacteriophage would attach to its host, inject its nucleic acid and then enter the lysogenic cycle. Some phage, like t4, are only capable of lytic growth lysogenic cycle. Bacteriophage replication lytic cycle and lysogenic. This occurs when the r genome or that of another temperate phage is induced to exit the bacterial. In lysogenic cycle, the lytic vegetative phage becomes integrated with the host cell chromosomes and is converted into prophage without lysis of bacterial cell.
These cycles are the lysogenic life cycle and the lytic life cycle. The lysogenic cycle is one of the two cycles of viral reproduction which involves integration of the bacteriophage nucleic acids into the host bacterium genome, creating a prophage. The action of most of viral genes is to enable the viruses to infect their respective host cells, multiply by using the host machinery such as enzymes and ribosomes and then causing the lysis of cells. During infection a phage attaches to a bacterium and inserts its genetic material into the cell. During the bacteriophage lysogenic cycle free pdf ebook. Lysis of t4infected bacteria in the absence of lysozyme. While lytic phages kill the cells they infect, temperate phages establish a persistent infection of the cell without killing it. The wild type of this virus has a temperate life cycle that allows it to either reside within the genome of its host through lysogeny or enter into a lytic. Induction can be induced artificially using ultraviolet rays or. Lysogenic cycle some viruses, such as herpes and hiv, enter the host cell but remain hidden for years. Depending on the life cycle, phages can either by lytic virulent or lysogenic temperate. Abortive infection of lysogenic bacillus subtilis 168spo2. Genetic recombination occurs between the viral dna and the bacterial genome as the viral dna is inserted into the bacterial chromosome. The lytic cycle involves the reproduction of viruses using a host cell to manufacture more viruses.
Transcriptional regulation in bacteriophage lambda examination of single cells, and other studies, showed that. The lysogenic cycle is less flashy and less gory than the lytic cycle, but at the end of the day, its just another way for the phage to reproduce. Bacteriophage t4 attacks bacteria 8 generalized viral life cycle. Bacteriophages capable of a lysogenic life cycle are termed temperate bacteriophages. A bacteriophage reproduces by one of two types of life cycles. Two major cycles of multiplication of bacteriophages are. Lysogenic cycles also can be terminated through the process of induction or, indeed, through prophage curing. The phage genome can be made of either double or singlestranded dna or rna, depending on the bacteriophage in question. Some phage are also capable of maintaining their chromosome in a stable, silent state within the bacteria. There are many similarities between bacteriophages and animal cell viruses. The zip file has teacher notes, a power point, video with questions for students to follow along and a quiz. Difference between lytic and lysogenic cycle of bacteriophage this video explains the difference between lytic and lysogenic cycle of.