Microbiology Chpt 6 viruses – Flashcards
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| Could viruses be seen by the first microscopes? |
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| No they were too small |
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| Who proposed the term virus? |
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| Louis Pasteur |
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| What did Ivanovski and Beijerinck showed? |
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| disease in tobacco was caused by a virus |
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| Who discovered an animal virus that caused foot and mouth disease in cattle? |
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| Loeffler and Frosch |
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| Describe what viuses can and cannot do? |
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| -Can infect every type of cell -Cannot exist independently from the host cell, so they aren't considered living things BUT since they can direct life processes they are considered more than a lifeless molecule. They have to have intrcellular parasites refered to as infectious partilcles, either active or inactive |
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| HIV is? |
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| a retrovirus with an RNA genome |
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| Describe the DNA virus of Eukaryotes enveloped with which kind of genosome |
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| enveloped Double -strnded genome -Poxviruses -Herpesviruses -Adenoviruses (linear DNA) -Papovvirses (circular DNA |
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| Describe the DNA virus of Eukaryotes Nonenveloped with which kind of genosome |
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| It has all the double standed geno plus one single stranded genome Parvoviruses |
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| segemented - |
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| individual genes exist on seperate pieces of RNA |
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| A virus is a tiny infectious? |
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| Particle |
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| Viruses are known to attacka. Plants b. bacteria c. fungi d. All organisms |
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| d. All organisms |
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| The nucleic acid of a virus is a. DNA only b. RNA only c. Both DNA and RNA d. Neither RNA or DNA |
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| d. Neither RNA or DNA |
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| the general steps in a viral multiplication cycle is |
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| absorption penetration synthesis assembly and release |
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| a prophage is an early stage in the development of an a. bacterial virus b. poxvirus c. lytic virus d. enveloped virus |
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| a. bacterial virus |
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| In general, RNA virses multiply in the cell____, and DNA virsus multiply in the cell________. |
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| In general, RNA virses multiply in the cell cytoplasm, and DNA virsus multiply in the cell nucleus. |
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| Viruses cannot be cultivated in? |
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| blood agar |
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| clear patches in cultures that indicate sites in virus infection are called? |
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| plaques |
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| list viral infections |
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| rabies, cold sores, genital warts, mumps rubella |
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| True or False: In lysogeny, viral DNA is inserted into host chromosome |
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| True |
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| True or False A viral capsid is composed of subunits called virions |
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| False A viral capsid is composed of subunits called caposomers |
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| True or false: The envelope of an animal virus is derived from the cell wall of its host cell |
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| False The envelope of an animal virus is derived from the cell MEMBRANE of its host cell |
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| True or False: The nucleic acid of animal viruses enter the cell through a process called translocation |
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| False The nucleic acid of animal viruses enter the cell through a process called penetration |
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| True/ False Viruses that persist in the (host) cell and cause recurrent disease are called latent |
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| True |
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| Are viruses alive? |
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| If viruses are unable to multiple independently from the host cell, they are not living things. The other debate is even though viruses do not exhibit most life process they do effect them. |
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| Discuss the size of microorganisms |
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| virsus are the smallest infectious agents and usually can only be seen with the help of a electron microscrpe |
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| DISCUSS the function and structure of viral capsids |
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| shell that surrounds the nucleic acid in the central core Made up of protein molecules two different types-Helical and Icosahedral |
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| Distinguish between enveloped and naked viruses? |
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| Virsus that possess an additional covering external to the capsid is called the envelope viruses that consist of only a nucleocapsid are considered naked viruses |
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| explain the importance of viral surface proteins or spikes |
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| essential for attachment. |
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| explain the importance of viral surface proteins or spikes |
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| essential for attachment. |
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| Describe the multiplication cycles in animal virsus? |
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| absorption pentration uncoating synthesis assembly release |
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| Adsorption |
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| specific attachment |
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| penetration |
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| entry of viral genome |
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| uncoating |
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| release of viral genome |
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| synthesis |
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| new viral products made |
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| assembly |
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| new viruses are made in the cell |
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| release |
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| often causes the host cell to lyse |
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| RNA viruses synthesis |
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| replicated and assembled in the cytoplasm |
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| DNA Viruses synthesis |
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| enter host cell's nucleus where they are replicated and assembled |
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| Explain what cytopathic effects are? |
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| virus -induced damage to the cell that alters its microscopic appearance |
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| Explain what cytopathic effects are? |
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| virus -induced damage to the cell that alters its microscopic appearance |
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| RNA viruses synthesis |
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| replicated and assembled in the cytoplasm |
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| medical importance of viruses |
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| -infectious disease chronic affliction association type 1 diabetes multiple sclerosis cancer |
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| nucleocapsid |
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| The capsid and the nucleic acid togther are called |
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| fully formed virus that is able to establish an infection in a host cell |
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| virion |
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| What are the 2 different types of viral capsid? |
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| helical and isosahedral |
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| Viral Capsid: Constructionmade up ofprotects? |
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| Viral Capsid Construction from identiacal subunits called capsomers Made up of protein molecules -to protect DNA protects DNA from the enviroment |
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| Describe icosahedral capsid? |
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| three-dimensional, 20 sided figure with 12 evenly spaced corners Although they all display this symmetry, there are wide variations |
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| Describe complex capsids |
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| land on cell only effect bacteria shape is not symmetrical caontain tail fibers and capsid head |
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| Describe the viral envelope |
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| takes a bit of host cell membrane in the form of an envelope in the envelope, some or all of the regular membrane proteins are replaced with viral proteins some proteins form a binding layer between the envelope and the capsid H1N1 |
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| What are glycoproooteins |
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| remain exposed as spikes; essential for attachment |
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| Name the functions of viral capsid envelope? |
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| Protects nucleic acids help introduce the viral DNA and RNA into suitable host cell Stimulate the immune system to produce antibodies that can protect cell against future infections |
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| List 4 types of nucleic acid stands that can be used as a virus genomes? |
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| 1. double stranded DNA 2. Single stranded RNA 3. Single Stranded DNA 4. Double stranded RNA |
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| What are the 2 major types of virus capsid structures? |
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| 1. Helical 2. Icosahedral |
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| Function of viral capsid/envelope? |
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| Protects nucleic acids Help introducre the viral DNA or RNA into a suitable host cell stimulate the immune system to produce antibodies that protect the host cells against future infections |
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| genome |
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| the sum total of genetic informationcarried by an orgainsm Contain DNA or RNA not BOTH |
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| Some viruses are exception to typical DNA and RNA formation ParvovirusesReoviruses ? |
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| Parvoviruses- Contain single stranded DNA Reoviruses contain double stranded RNA |
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| WHich bacteria type is stained with crystal violet when performing Gram stain? |
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| Gram positive cells |
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| What is the basis for the differnital nature of the gram stain procedure? |
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| cell walls differ in composition among bacterial types and thus bind stain differently |
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| How are viruses are classified and named? |
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| Main criteria'structure chemical composition similarities in genetic makeup |
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| Viral enzymes found in nucleocapsid? |
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| -polymerases (makes polymers DNARNA makes polymers -reverse transcriptase |
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| viral enzymes- found in envelope |
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| hemagglutinin neuraminidase |
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| What is required for viral multiplication? |
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| Host cells and specific interaction between host cell and virus |
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| Multiplication cycles in animal viruses? |
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| 1. Absorption-specific attachment (spikes) 2. Penetration-entry into genome 3. uncoating-release of viral genosome 4. Synthesis-new viral products are made 5. assembly- new viruses are made in the cell 6. release-often causes the host cell to lyse |
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| Describe adsorption? |
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| virus encounters susceptible host cells adsorbs specifically to receptor sites on the cell membrane because of exact fit required; viruses have a limited host range |
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| Penetration- |
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| whole capsid enters flexible cell membrane of the host is penetrated by the whole virus or its nucleic acid The viral envelope can also directly fuse with the host cell membrane (influenza; mumps) |
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| endocytosis |
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| entire virus engulfed by the cell and enclosed in vicuole or vesicle (herpes) |
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| uncoating |
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| enzyme in the vacuole dissolve the envelope and capsid the virus is now uncoated (nucleic acid free in cytoplasm |
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| synthesis |
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| make more RNA and DNA -free viral nucleic acid exerts control over the host's synthetic and metabolic machinery |
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| How is the DNA viruses synthesis? |
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| DNA viruses-enter host cell's nucleus where they are replicated and assembled |
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| Where is the RNA viruses synthesis? |
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| RNA viruses-replicated and assembled in the cytoplasm |
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| Assembly and release MATURE VIRUS PARTICLES ARE CONSTRUCTED FROM |
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| THE GROWING POOL OF PARTS nucleic acid and capsid spikes |
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| Assembly and release Nonenveloped and complex viruses are released when? |
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| Cell lysis or ruptures and the host cell dies |
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| Assembly and release enveloped viruses are liberated by? |
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| budding or exocytosis |
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| Assembly and release Entire length of the cycle to assemble and release |
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| 8-36 hours |
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| Damage to the host cell and persistent infections Cytopathic effects |
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| virus-induced damage to the cell that alters its microscopic appearance |
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| Damage to the host cell and persistent infections Inclusion bodies- |
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| compacted masses of viruses or damaged cell organelles |
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| Damage to the host cell and persistent infections Synctia |
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| Fusion of cells- Disease example: RSV |
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| Damage to the host cell and persistent infections Latent infections |
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| infections that are in the body but can show up years later Disease Example: HIV and Herpes |
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| Damage to the host cell and persistent infections Transformation |
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| Oncogenic (cancer causing) Disease example: HPV- human papiloma virus and Hepititis B |
