chapter 18 - Viruses and Bacteria Relative size of a virus,...

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1 Viruses and Bacteria Relative size of a virus, bacteria and animal cells Virus Bacterium Animal cell Animal cell nucleus 0.25 μm Structure of some viruses: DNA , RNA , protein coats (capsids, made of capsomeres), membranous envelopes Capsomere of capsid RNA Capsomere DNA DNA RNA Capsid Head Tail sheath Tail fiber Membranous envelope 18 × 250 nm Glycoprotein 70–90 nm (diameter) Glycoprotein 80–200 nm (diameter) 80 × 225 nm Influenza viruses ssRNA Tobacco mosaic virus Adenoviruses dsDNA Bacteriophage T4 50 nm 50 nm 50 nm 20 nm What is a virus? Viruses Æ infectious particles Æ nucleic acid enclosed in protein coats bacterial viruses = bacterio… “ phages viral genomes: DNA or RNA single-stranded or double-stranded Class/Family Envelope Examples/Disease I. Double-stranded DNA (dsDNA) Adenovirus No Respiratory diseases, animal tumors Papovavirus No Papillomavirus (warts cervical Animal Viruses (warts, cervical cancer): polyomavirus (animal tumors) Herpesvirus Yes Herpes simplex I and II (cold sores, genital sores); varicella zoster (shingles, chicken pox ); Epstein-Barr virus ( mononucleosis , Burkitt’s lymphoma) Poxvirus Yes Smallpox virus, cowpox virus Class/Family Envelope Examples/Disease II. Single-stranded DNA (ssDNA) Parvovirus No B19 parvovirus (mild rash) III. Double-stranded RNA (dsRNA) Reovirus No Rotavirus (diarrhea), Colorado tick fever virus
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2 Class/Family Envelope Examples/Disease IV. Single-stranded RNA (ssRNA); serves as mRNA Picornavirus No Rhinovirus (common cold ); poliovirus, hepatitis A virus, and other enteric (intestinal) viruses Coronavirus Yes Severe acute respiratory syndrome ( SARS ) Flavivirus Yes Yellow fever virus, West Nile virus, hepatitis C virus Togavirus Yes Rubella virus, equine encephalitis viruses Class/Family Envelope Examples/Disease
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chapter 18 - Viruses and Bacteria Relative size of a virus,...

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