Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Skip to content B. Sc Agriculture Books. Download free pdf of the book of Agricultural Microbiology Microbiology often has been defined as the study of organisms and agents too small to be seen clearly by the unaided eye—that is, the study of microorganisms.
Interactions of the Rickettsia, Ehrlichia, Coxiella and Bartonella with the host cell. Pathogenesis, epidemiology and clinical syndromes associated with Rickettsia, Ehrlichia, Coxiella and Bartonella. Methods for treatment, prevention and control of rickettsial diseases. Post a Comment. Medical Lecture Notes. Medical Android. Search This Blog. Home Contact me.
Vote For This Blog. Bacterial identification in the diagnostic laboratory versus taxonomy. Posted by Dr. Fermentation refers to the formation of alcohol or lactic acid from sugar 2. Observed that yeast cells only come from other yeast cells b. Demonstrated that yeast can grow with or without oxygen, that is they are facultative anaerobes c. Showed that bacteria ferment grape juice into acid, while yeast ferment the juice into alcohol d.
Buchner's experiments: a. Showed that enzymes in cell extract cause fermentation b. Initiated the field of biochemistry and the study of metabolism E. The germ theory of disease states that microorganisms can cause disease 2. Koch's experiments: a. Demonstrated relationship between a microorganism and a disease b. Koch's Postulates are a series of steps to show that a specific microorganism causes a particular disease c. Koch and colleagues significantly advanced microbiology lab techniques F.
Semmelweis — handwashing to reduce infection 2. Lister — developed aseptic techniques including phenol solution to treat bandages and surgical instruments, which significantly reduced post- surgical infections 3. Jenner's smallpox vaccine led to field of Immunology 5. Snow's studies of cholera epidemic in London started epidemiology, the study of occurrence, distribution, and spread of diseases in populations IV.
The modern age of microbiology A. Examining the basic chemical reactions of life B. Determining how genes work using genetics, molecular biology, and recombinant DNA technology C. Determining the role microorganisms play in the environment. Micro organism By adelokun shakirat. This may occur by by budding from the cell surface, as occurs with many enveloped viruses.
In this case capsid proteins and nucleic acid condense directly adjacent to the cell membrane and viral-coded envelope proteins, introduced into the cell membrane, concentrate in the vicinity of capsid aggregates. The membrane surrounding the nucleocapsid then bulges out and becomes "nipped off" to form the new enveloped virion.
Some viruses utilize the cellular secretory pathway to exit the cell. Virus particles enclosed within Golgi- derived vesicles are released to the outside of the cell when the transport vesicle fuses with the cell membrane. Disintegration or lysis of the infected cell can also result in the release of intact infectious virions. Life cycle of bacteriophages - Bacteriophages phages are viruses that infect bacteria - There are two types — Lytic bacteriophages and temperate bacteriophages - a.
Lytic life cycle - Bacteriophages replicating through the lytic cycle are so named because they lyse the host bacterium as a normal part of their life cycle e. T4 Coliphages - Lytic cycle consist of the following replication steps i. Most bacteriophages adsorb to the bacterial cell wall although some are able to adsorb to flagella or pili. Specific strains of bacteriophages can only adsorb to specific strain of host bacteria. This is known as viral specificity.
Penetration - In the case of phages adsorbing to bacterial cell wall, a phage enzyme lysozyme drills a hole in the bacterial wall and the phage injects its genome into the bacterial cytoplasm. Some phages accomplish this by contracting a sheath which drives a hollow tube into the bacterium. This begins the eclipse period.
The genome of phages which adsorb to flagella or pili enter through these hollow organelles iii. Maturation or assembly - Phage DNA and capsids are assembled into complete viruses v. Lysogenic life cycle of Temperate Bacteriophages - Bacteriophages capable of lysogenic life cycle are termed temperate phages. The cycle begins by the phage adsorbing to the host bacterium or lysogen, and injecting its genome as in the lytic life cycle.
However, the phage does not shut down the host cell. At this stage the virus is called a prophage. The bacteriophage genes are activated and new bacteriophages are produced as in the lytic life cycle. Replication of animal viruses 3. Entry - Differs with entry of animal viruses because plants have a thick, rigid and impermeable cell walls with cellulose and pectin separating plant cells from one another - Several ways in which plant viruses enter their hosts include one of the following o through wounds caused by mechanical damage or injury breaching cell wall and transiently breaching the plasma membrane of underlying cells o Injury due to mouthparts herbivorous arthropods o Injection of viruses directly into plant cells through piercing mouth parts of sap-sucking insects o Vertical transmission through infected seeds o Via pollen o Through grafting of infected tissue onto a health plant tissue - Examples of viruses infecting plants include; Tobacco mosaic virus - Tomato spotted wilt virus b.
Uncoating - Viruses enter through the cytoplasm and uncoat by processes such as dissociation or enzyme-mediated partial degradation of particles - This involves partial removal of protein coat shell in the cytoplasm c. Release - Viral genome is released as a naked RNA or as a nucleoprotein complex - Movement of virus into neighbouring cells takes place through the plasmodesmata froming connection between cells VIRUS HOST RANGE All viruses have a limited host range and even within a host they attach to and invade only those cells with the appropriate receptor sites.
Bacteriophage viruses only attack man in binding to and injecting , the first reports of a their DNA into a bacterial chimpanzee being infected with cell. HIV was reported. The bacteriophage lambda only attacks cells which contain the receptor for binding the sugar maltose.
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