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Premedical - Biology

Viruses Non-cellular organisms. Premedical - Biology. Non-cellular: viruses are i nfectious particles plant, animal, bacterial = bacteriophages virion = nucleic acid + protein coat (capsid) and another envelope similar to membrane (enveloped viruses)

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Premedical - Biology

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  1. Viruses Non-cellular organisms Premedical - Biology

  2. Non-cellular:viruses areinfectious particles plant, animal, bacterial = bacteriophages • virion = nucleic acid + protein coat (capsid) and another envelope similar to membrane (enveloped viruses) • bacteriophage = icosahedra head + tail, base plate, fibers

  3. Enterobacteria phage T4 infects Escherichia coli viral DNA injection

  4. Icosahedral models, left to right: fivefold, threefold, and twofold axes

  5. CAPSID CONFIGURATION IN NAKED AND ENVELOPED VIRUSES. Capsid - protein shell subunits - Capsomers

  6. Capsids Helical Polyhedral

  7. Tobacco mosaic virus

  8. Papillomavirus

  9. virus classification • host specification: plant, animal, bacteria • DNA a RNA virus: ds DNA, ss DNA, ds RNA, pos ss RNA, neg ss RNA, rev trans diploid ss RNA, rev trans circular dsDNA • structure: symmetry helical, complex, icosahedral, capsid, envelope, number of capsomer

  10. ds DNA, ss DNA, ds RNA, ss RNA, rev trans diploid ss RNA, rev trans circular dsDNA

  11. replication reverse transcription translation Protein RNA DNA Reverse transcriptase = enzyme overwriting RNA to DNA transcription

  12. Retrovirus, Lentivirus, pos ssRNA-RT, encapsulated: HIV-1, HIV-2

  13. Viruses can reproduce only within a host cell • Obligate intracellular parasites • only a limited range of host cells – host specificity • eukaryotic viruses are tissue specific • lack ribosomes … • Lytic cycle – virulent viruses

  14. Lytic cycle of virus reproduction • adsorption virus to cell • penetration virus or viral NA into cell • replication, transcription and translation • assembling new virus particles (self-assembly) • transfer to daughter cells: effect on the cell: death of the cell – lyses (hundreds or thousand) cytopathy effect (exocytose)

  15. Lysogenic - virogenic cycle = integration of the viral nucleic acid into the host genome as provirus (prophage) • replication with the DNA of the host cell • latent viruses – the cell is not damaged • virus is transferred to daughter cells • viruses as vectors of oncogeny

  16. Temperate phages Latent viruses

  17. Tumor viruses - transformation of eukaryotic cells DNA viruses – oncogenes RNA viruses = retroviruses

  18. RNA viruses Poliomyelitis - polio Rhinitis – cold Influenza – flu Encefalitis Rubella – measles Ger. Parotitis - mumps Morbilli – measles Rabies HIV-AIDS

  19. DNA viry: Adenoviruses - respiratory disease conjunctivitis gastroenteritis Oral herpes - herpes simplex virus infectious mononucleosis - Epstein-Barr virus (EBV) Smallpox - Variola major and minor Human Papilomavirus - warts (verrucae), cancers of cervix, vulva, vagina

  20. Prions • degeneration brain disease • infectious particles • contain proteins, NA wasn‘t proved • abnormal prion = product of mutated genes

  21. Disease They cause an infection in sheep called scrapie and cattle bovine spongiform encephalopathy ("mad cow" disease).

  22. Prion protein • occurrence in two isoforms: normal PrPC (C=cellular) abnormal PrPSC (SC=scrapie) • PrPC – prevalence of alpha helix a little beta structure • PrPSC – prevalence of beta structure • presence of PrPSC induces PrPC change = normal protein to abnormal - runs as chain reaction

  23. hereditary disease = gene mutation → abnormal protein • transfer between species is rare, but might be possible with a long period of latency • transfer from human to human: by growth hormone, brain electrodes

  24. Human diseases Creutzfeld-Jacob disease: affection of the grey brain cortex, severe neurological symptoms with quickly proceeded dementia) kuru: Papua-New Guinea: disability of movement coordination, paralysis, dementia – disease is extension by ritual cannibalism

  25. Neural degeneration in a prion infection. It is a slice from the brain of a person who died of kuru. The large fluid-filled holes are places where neurons have died.

  26. Campbell, Neil A., Reece, Jane B., Cain Michael L., Jackson, Robert B., Minorsky, Peter V., Biology, Benjamin-Cummings Publishing Company, 1996 –2010.

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