Chapter 19 – Bacteria & Viruses History Iwanowski and Beijernick . Ppt Powerpoint Presentation slides-Medical Slideshow PAP Bacteria and Virus Notes Ch 19

Chapter 19 – Bacteria & Viruses History Iwanowski and Beijernick .

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Slide 1 :

Chapter 19 – Bacteria & Viruses

Slide 2 :

History Iwanowski and Beijernick (1890’s) Worked on Tobacco Mosaic Virus (infects tobacco and tomato leaves). Creates mosaic pattern on leaves. Made a juice of the infected leaves and then put this juice through a filter. Rubbed the filtered juice onto leaves. Still became infected. Concluded that whatever these disease causing particles were, they were very small (smaller than bacteria). Named them viruses meaning “poison”.

Slide 3 :

Stanley (1935) Purified TMV into a crystal. Living particles don’t crystallize therefore, viruses are non-living pathogenic (disease causing) particles.

Slide 4 :

Viruses Particles of nucleic acid, protein and sometimes a lipid envelope. Obligate intracellular parasite (can only replicate within a living cell)

Slide 5 :

Structure of a virus Small – 20nm (polio virus) – 350nm (small pox virus) Single type of nucleic acid (RNA or DNA but never both) Protein coat – capsid Some have envelopes (made of lipids)outside of capsid Surface projections made up of lipids for attachment onto host cells Are specific to their host

Slide 6 :

Shapes Shapes are Rod Helical Icosahedral (20 sides)

Slide 7 :

HIV Envelope Projections

Slide 8 :

Bacteriophage Infect E. coli bacteria Attach with tail fibers onto cell. Inject nucleic acid into cell

Slide 9 :

The Lytic Cycle Get in, replicate and get out to invade other host cells Virulent (Disease causing) The cold, rubella (German measles), mumps Release Attachment at Receptor site Entry Replication Assembly

Slide 10 :

The Lytic Cycle of Virus infection Attaches onto host cell Injects DNA into host cell Replication of Viral parts Reassembly of virons Lysis – bursting out Viruses that reproduce only by the lytic cycle are called Virulent

Slide 11 :

Lysogenic Infection Virus embeds its DNA into hosts DNA which is replicated with host cell’s DNA. Remains unnoticed for sometimes years AIDS, cold sores, chicken pox, hepatitis Prophage Attachment Integration Cell multiplication & Injection of nucleic acid Prophage remains unnoticed and not transcribed

Slide 12 :

Viral Diseases Measles, Mumps, Rubella, Rabies, the Cold, the Flu, Influenza, Hepatitis, AIDS, Chicken pox, Small pox, Polio, Yellow fever, Meningititis, some cancers Vaccines are small doses of either killed, altered or live viruses. Body builds up antibodies against virus

Slide 13 :

Diseases caused by viruses AIDS The Cold Measles Mumps Rubella Chicken pox/Shingles Small Pox Hepatitis SARS The Flu Ebola HPV Bird Flu Polio

Slide 14 :

The Different forms of Viruses Retroviruses – AIDS. Contains RNA instead of DNA. Goes from RNA to DNA to RNA to protein. Normal is DNA to RNA to protein. Viroids – another disease causing agent but no capsid, only the RNA. Found only in plants Prion – viral proteins that cause diseases. Scrapie in sheep degrades nervous system. Mad Cow disease (Bovine spongiform encephalopathy) in cows – puts holes into brain. In humans, its Creutzfeld-Jakob disease & Kuru.

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Measles, Mumps, Rubella, Rabies, the Cold, the Flu, Influenza, Hepatitis, AIDS,AIDS; The Cold; Meas more Measles, Mumps, Rubella, Rabies, the Cold, the Flu, Influenza, Hepatitis, AIDS,AIDS; The Cold; Measles; Mumps; Rubella; Chicken pox/Shingles; Small Pox … less

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