Microbiology Final- Chapter 13 (Viruses) – Flashcards
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| viruses are what type of parasites? |
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| viruses are obligate intracellular parasites (as are some bacteria-table 13.1) |
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| how do viruses multiply |
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| by using cells' synthetic machinery! |
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| what range of diameter do Viruses have? |
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| 20nm and up! |
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| what length do viruses have? |
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| 20-1000 nm |
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| Host range=__________ |
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| organisms that viruses infect |
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| what 3 hosts do viruses infect? |
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| plants, animals, and bacteria |
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| what is an example of a plant virus? |
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| TMV- Tobacco Mosaic Viruses |
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| what is are four examples of animal viruses? |
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| Herpes, influenza (flu) virus, poliovirus and rabies virus |
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| Genome= |
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| viral nucleic acid (NA) |
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| Capsid= |
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| viral protein coat- fig 13.2 |
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| Capsomere= |
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| protein subunits of the capsid |
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| Nucleocapsid= |
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| NA + capsid |
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| Virion= |
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| complete, fully developed, infectious viral particle. |
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| The viral nucleic acid (genome)-can be: |
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| 1.DNA or RNA (never both in a VIRION)! 2. Non-segmented or segmented 3. Linear or circular 4. Double or single stranded 5. Single stranded genome: -Is a sense or (+) strand if it behaves like mRNA -Is antisense or (-) strand if it can't act like mRNA |
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| when is a single-stranded genome a sense (+) strand? |
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| if it behaves like mRNA! |
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| when is a single-stranded genome a antisense (-) strand? |
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| when it can't behave like mRNA |
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| Viral morphology (shape) is: |
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| based on capsid architecture |
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| Viral Morphology- Helical viruses: |
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| -long or curved rods/ threads |
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| What is an example of a Helical virus? |
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| TMV, rabies virus, ect. |
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| Viral Morphology: Polyhedral viruses: |
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| Icosahedrons structure (many sided) |
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| what is an example of a polyhedral virus? |
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| Adenoviruses, and picornaviruses |
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| Viral Morphology: Enveloped Viruses: |
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| Envelope surrounds the capsid, is derived from cellular membranes |
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| what is an example of and enveloped helical virus? |
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| Influenza virus |
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| what is an example of an enveloped polyhedral virus? |
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| herpes simplex virus |
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| Viral Morphology: Complex viruses: |
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| Have complex structure! |
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| what is an example of a complex virus? |
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| T-even phages (T2 and T4) and poxviruses (smallpox virus and cowpox virus). |
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| Viral Taxonomy is what? |
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| viral classification! |
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| Viral Taxonomy is based on what 3 things |
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| nucleic acid type, morphology and replication strategy (retrovirus-HIV example) |
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| Viral Taxonomy-family, genus/species names: |
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| -Family suffix is viridae ex) retrovirade -Genus suffix is virus ex) lentivirus -Species: a descriptive name ex) HIV |
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| Growing Viruses in the Lab: 1.Bacteriophages |
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| Example-T4 grown in E. coli: -Lawn of E.coli on AGAR + T4-> areas of clearing on agar, called PLAQUES! -BROTH culture of E. coli + T4-> CLEARING of broth is an indication of T4 growth! |
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| Growing Viruses in the Lab: 2.Animal viruses-where can they be grown in? |
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| 1.Lab animals 2.Embryonated eggs 3.Cultured cells (cell lines): -cells + virus = cytpathic (cell disease) effects (CPE) indicates growth |
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| Growth Viruses in the Lab: 3. Cell Line types (2) |
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| 1. Primary cell line 2. Continuous cell line (CCL) |
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| Primary cell lines: |
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| cells with finite lifespan, cultured directly upon removal from animal. |
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| Continuous cell line (CCL): |
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| Immortalized cells-growing indefinitely in culture. |
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| Viral Multiplication steps: |
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| 1.Attachment 2.Penetration 3.Uncoating 4.Biosynthesis -includes replication, transcription, and translation 5.Maturation (assembly of body parts) 6.Release |
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| Types of Bacteriophage Multiplication: |
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| Lytic and Lysogentic cycles |
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| Lytic and Lysogenic cycles are present depending on virus type: |
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| -Both cycles found in lambda phage -Only lytic cycle in T-even phages. |
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| Lytic Cycle: |
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| Ends with lysis and death of host cell |
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| what is an example of a type of phage that uses the lytic cycle: |
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| T-even phages attacking E. coli |
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| Lysogenic Cycle: |
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| Phage DNA becomes inserted i host cell genome as PROPHAGE |
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| what is an example of a phage that uses the lysogenic cycle? |
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| Lambda phage attacking E. coli |
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| how does Lambda phage transfer bacteria DNA to a different bacterium?: |
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| via TRANSDUCTION |
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| Animal Virus Multiplication: Where do DNA VIRUSES multiply: |
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| multiply in the nucleus -HOST enzymes transcribes viral DNA to give mRNA -(EXCEPTION: in PROXVIRIDAE, viral enzyme does that!) |
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| Do ALL hosts enzymes of ANIMAL viruses transcribe viral DNA to give mRNA? |
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| NO!!! PROXVIRADAE- this viruses enzymes transcribes its own DNA to make mRNA. |
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| Animal Virus Multiplication: In Retroviruses: (ex HIV, an RNA Virus) |
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| -Viral RNA is copied to make DNA by RNA-DEPENDENT DNA POLYMERASE, also called REVERSE TRANSCRIPTASE! -DNA moves from cytoplasm to the nucleus and inserts into the host genome as PROVIRUS |
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| Animal Virus Multiplication: RNA Viruses: |
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| Multiply in the CYTOPLASM |
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| What are the Enzymes involved in RNA replication? |
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| RNA-dependent RNA polymerase (RRP) |
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| Viruses and Cancer: Why is viral cause of cancer difficult to establish/diagnose? |
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| Because: 1.Viruses -are difficult to see -many infect cells without causing cancer. 2.Cancers: -are not contagious -may not develop until long after viral infection is established. |
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| Viruses and Cancer: Viruses that cause cancer are called oncogenic viruses: |
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| -many DNA viruses are oncogenic (ex-Papilloma virus) -Oncogenic RNA viruses are found only in Retrovirade-and RNA Virus! (HIV) |
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| Viruses and Cancer C. Cancer=uncontrolled cell proliferation cells become transformed and show what? |
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| 1. Loss of contact inhibition 2. Chromosome changes 3. Tumor-specific transplantatioleus)n antigens-TSTA-(on cell surface) 4. T antigens (in nucleus) |
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| Latent vs. slow viral infections: -Latent: |
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| -viruses remains for long periods without diseases -infectious virus appears suddenly -usually not fatal-does not kill-ex. -cold sores by latent HSV-1 -Shingles by latent chickenpox virus |
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| Latent vs. slow viral infections: slow/persistent |
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| -a disease process; occurs over long period of time -infectious virus gradually builds up -usually fatal-ex- -AIDS dementia by HIV -SSPE by measles virus |
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| Prions: Prion disease is caused by what? |
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| an infectious protein called prions |
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| a Prion disease in sheep, cattle and humans |
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| -sheep: scrapies disease (Sc) -cattle/cow: mad cow disease (also called bovine spongiform encephalopathy-BSE) -Humans: Creutzfeld-Kakob disease and Kuru |
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| Viroids: Viroid disease: |
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| -Is a plant disease-cause plant diseases -caused by naked RNA |
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| Viroids: Properties: |
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| -The RNA is 300-400 nucleotides long -lik introns, the RNA does not code for a polypeptide |
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| Viroids: Examples: |
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| -coconut cadang cadang viroid (CCCV) disease -Potato spindle tuber viroid (PSTV) disease |
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| fghfh |
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| fhfhf |
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