Lecture 14Outline of Last Lecture 1. Viruses2. Virus Structures3. Life of A VirusOutline of Current Lecture 1. Viruses continued…2. Virology3. Medical important of viruses4. Microbial NutritionCurrent LectureEntry of Animal Viruses into Host Cells- Endocytosis of naked virus AnimationAttachment: Early Phase- Entry- Nucleic acid is now inside, decision point with viruses. Become lytic or lysogenic?Release of progeny, if Host health good, Host decides to be…- Lytic: Rapid growth, rupture in host cell Lysis- Lysogenic: Silent viral infection, viral genome is incorporated into host genome, when divides, each daughter cell has virusBacterial phague- attack bacteria (alternate between these states)Lysogenic creates temperant phague… Prophase: virus to be. Can be induced and become lytic again- Human lysogenic virus= Herpes, Shingles NEXT Virus is in… Lysogenic or Lytic decided. Replication to SynthesisEarly genes: Lysogenic decision, takes over gene expression of hostMiddle genes: DNA/RNA polymerase viral genome replication late gene expression BSC 160 1nd EditionLate genes: Capsid scaffolding proteins cell lysisLate phase: Translation of proteins, Assemble viruses, Release of virus Animations: 13.8, 13.9, 13.10 in EtextbookVirology- Challenge to study virus: getting sick, multiple viruses in different versions, Viruses are obligate intracellular parasitesneed host , studying animals is a last resortMedical Importance of VirusesViruses are the most common cause of acute infections- Possible connections between viruses & chronic afflictions of unknown cause- Viruses are major participants in earth’s ecosystemDetection & Treatment of Animal Viral Infections- More difficult than other agents- Consider overall clinical picture, take appropriate sampleInfect cell culture- look for characteristic cytopathic effectsScreen for parts of virusScreen for immune response to virus (antibodies)Antiviral drugs can cause serious side effectsTo kill a virus, we have to attack our own cellsMicrobial Nutrition- Process by which we acquire nutrition from environment EnergyMacronutrients= Need to make up bioelements: Carbon, Oxygen, Nitrogen, Hydrogen + Phosphorus Micronutrients= Sulfure, Potassium, Magnesium, Calcium, Iron. Needed for cellular processesTrace elements= Cobalt, zinc, Molybdenum, Copper, Manganesse, Nickle . CofactorsGrowth Factors= have to be taken up by environment. Can’t be synthesized- Vitamins,
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