PowerPoint Presentation The Microbial World Introduction to Viruses and Bacteriophage Definition of a Virus • Viruses are segments of nucleic acid enclosed in a protein coat Poliovirus Properties of V[.]
The Microbial World Introduction to Viruses and Bacteriophage Definition of a Virus • Viruses are segments of nucleic acid enclosed in a protein coat Poliovirus Properties of Viruses • Small size: range ~0.02 - 0.3 micrometers Picornavirus (“little RNA virus”) is one of the smallest viruses, about 20 nanometers in diameter Smallpox virus, one of the largest viruses, about 300 nanometers, near the resolution of the light microscope Properties of Viruses • Various morphologies polyhedral helical spherical filamentous complex Poliovirus Herpes virus Ebola virus Coronavirus Rabies virus Lassa virus Properties of Viruses • Obligate intracellular parasites Human adenoviruses growing within the nucleus of an infected cell Properties of Viruses • Lack membranes and a means to generate energy Schematic Illustration of a of Hepatitis virus Properties of Viruses • Lack metabolic and biosynthetic enzymes Schematic illustration of Herpes simplex virus Type (HSV1) Properties of Viruses • Lack ribosomes and a mechanism for their own protein synthesis Arenaviruses are an exception; they contain all classes of ribosomal RNA derived from the host, Properties of Viruses • Do not grow in size Viruses grow by independent synthesis and assembly of their components inside of a host cell Human adenoviruses growing in the nucleus of their host cell Structure of Viruses • The viral genome is DNA or RNA • Most bacterial viruses contain double-stranded DNA • Many animal viruses contain ds DNA or ssRNA