Viruses and Bacteria

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Viruses and Bacteria. Bacterial sizes. Prokaryotes range from 1-5 μ m Exception: Epulopiscium fisheloni is 500 μ m!. Classification. Old system One kingdom: Monera New system 2 kingdoms Eubacteria (Domain Bacteria) Archaebacteria (Domain Archaea ). - PowerPoint PPT Presentation

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Viruses and Bacteria

Bacterial sizesProkaryotes range from 1-5 m

Exception: Epulopiscium fisheloni is 500 m!

ClassificationOld systemOne kingdom: MoneraNew system2 kingdomsEubacteria (Domain Bacteria)Archaebacteria (Domain Archaea)

Archae is more like us (Eukarya) because we share key genesBacteria ShapesBacillus (pl bacilli)Rod-shaped

Coccus (pl cocci)Spherical

Spirillum (pl spirilla)Spiral-shaped

Cell WallGram staining can be used to differentiate bacteriaThick wall of peptidoglycanpurple colorThin/no wallpink/red color

anthraxgonorrheaIdentify it!

Identify it!

Identify it!

Identify it!


Escherichia aurescens

Escherichia coliMovementSpiral movement

Glide on slime

Spirillum volutans

MyxobacteriumMetabolismBacteria can be either heterotrophic or autotrophicHeterotrophicdoes not produce own food sourceAutotrophicdoes produce own food source

Heterotroph typesChemoheterotrophs- take in organic molecules for energy and carbon sourceEX: E. coliPhotoheterotrophs- photosynthetic, but needs organic molecules for a source of carbon

Autotroph typesPhotoautotrophs- use light energy to convert CO2 and water into organic compounds and O2EX: cyanobacteria blue green algaeChemoautotrophs- make organic molecules from CO2 but use chemical reactions instead of lightLive deep in ocean vents

Releasing energyObligate aerobesneed O2 to liveEx Mycobacterium tuberculosisObligate anaerobesdie with O2Ex Clostridium botulinumFacultative anaerobeseither orEx E. coli

Growth and ReproductionBinary fissiongrow, double cellular components, and divide

Growth and ReproductionConjugation hollow bridge forms so that bacteria can exchange genetic material

Growth and ReproductionSpore formation bacteria can form spores when growth conditions become bad (too hot/cold, too dry, no food)Protective barrierWhen conditions are good again, bacteria will grow again

Importance of bacteriaDecomposers-

Nitrogen Fixers-

Human uses-History of VirusesIwanowski and Beijernick (1890s) 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.

History of VirusesStanley (1935) Purified TMV into a crystal. Living particles dont crystallize therefore, viruses are non-living pathogenic (disease causing) particles.

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

Structure of a VirusSmall 20nm (polio virus) 350nm (small pox virus)Single type of nucleic acid (RNA or DNA but never both)Protein coat capsidSome have envelopes (made of lipids)outside of capsidSurface projections made up of lipids for attachment onto host cellsAre specific to their hostStructure of a Virus

Viral ShapesShapes are RodHelicalIcosahedral (20 sides)

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

BacteriophageInfect E. coli bacteriaAttach with tail fibers onto cell. Inject nucleic acid into cell

The Lytic CycleGet in, replicate and get out to invade other host cellsVirulent (Disease causing)The cold, rubella (German measles), mumps

ReleaseAttachment at Receptor siteEntry ReplicationAssemblyThe Lytic Cycle of Virus infection

Attaches onto host cell Injects DNA into host cell Replication of Viral parts Reassembly of virons Lysis bursting outViruses that reproduce only by the lytic cycle are called Virulent

Lysogenic InfectionVirus embeds its DNA into hosts DNA which is replicated with host cells DNA. Remains unnoticed for sometimes yearsAIDS, cold sores, chicken pox, hepatitis

Prophage Attachment Integration Cell multiplication & Injection of nucleic acid Prophage remains unnoticed and not transcribedViral DiseasesMeasles, 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

Diseases Caused by VirusesAIDSThe ColdMeaslesMumpsRubellaChicken pox/ShinglesSmall PoxHepatitisSARSThe FluEbolaHPVBird FluPolio

The Different Forms of VirusesRetroviruses 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 plantsPrion 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.Diseases Caused by Bacteria and Viruses

What is a pathogen?

Okay, now the bad. Name the two ways bacteria cause disease in living organisms.

How can bacterial diseases be prevented?

How can they be treated?

Make a list of human diseases caused by bacteria.

What does it mean to sterilized a substance?

How can we prevent bacteria from spoiling our food?

What do viruses do to us to produce disease?

How are viral diseases treated and prevented?

What is non-effective at treating viral diseases?

List 9 diseases caused by viruses in humans

How are most plant diseases spread?

13.What is a prion?14.Why are viruses not considered to be alive?