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10 Cards in this Set
- Front
- Back
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Viral stages 1-5 of infection
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1.Adsorption: A virus recognizes, and attaches to, ahost cell.
2.Penetration: The virus, or its genetic core, entersthe cell. 3.Biosynthesis: Viral DNA, or RNA, directs the hostcell in producing copies of viral nucleic acids and in making viral enzymes andother proteins. 4.Assembling: Viral nucleic acids and proteins areassembled into new viral particles. 5.Release: Newly formed viruses are released fromthe infected cell. |
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Cell hosts for a virus requires?
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Acell will serve as a host for the synthesis of new viral particles only if theoriginal virus can recognize and lock onto the cell’ssurface. –Someviruses do not kill their host cells outright but enter a period of latency.
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Retroviruses
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Retroviruses areRNA viruses that use an enzyme called reverse transcriptase to synthesize a DNAmolecule for insertion into the host DNA; the integrated form is called a provirus. HIV is a retrovirus
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Prions
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Prions are infectious proteins.–Prions aresmall, infectious proteins linked to several rare, fatal degenerative diseasesof the nervous system.•Prions are misfolded versions of normal proteins found onbrain neurons and other cell types.•Prions can bind to normal proteins andrefold them, creating clumps of protein in the brain, destroying brain tissue.
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BSE (bovinespongiform encephalitis)
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-BSE(bovinespongiform encephalitis) or “madcow disease”affects cows and can cause variant Creutzfeldt-Jakob disease (vCJD)in humans; prions are also associated with a long known human-only version ofCJD.
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Virus shapes |
rodlike and polyhedral |
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Bacteria
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Bacteria are prokaryotic cells.–Structuralfeatures appear rather simple compared to more complex cells.•There is no nucleus or othermembrane-bound organelles.•Most bacteria have a cell wall that makesthem strong, semirigid, and gives them shape; coccus,bacillus, and spirillum (spirochete) are common cell shapes.
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–Bacteriareproduce
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Bacteriareproduce by prokaryotic fission,a process that can be repeated every 20 minutesn( various from one type to another).
•The chromosome is a single, circular DNA.•Some bacteria possess plasmids, small circles of extra DNA; plasmidsmay allow for fertility and for the transfer of drug resistance. –Streptococcusis a species of bacteria that causes respiratory tract infections and strepthroat; these bacteria possess the ability totransfer genes. |
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Meningitis
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Meningitis is infection of the meninges,the membranes that cover the brain and spinal cord (CNS).•Meningitis may develop in response to anumber of causes, including infectious agents, physical injury, cancer, orcertain drugs. •Infectious meningitis, the most commonform, is typically treated with antibiotics and requires close observation.••5 Types:–TypeA–Type B–TypeC–TypeY–TypeW-135
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MechanismsUsed by Normal Flora to Competitively Exclude Pathogens
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•Coverbinding sites used for attachment by pathogens•Useup available nutrients•Producecompounds that are toxicto other bacteria•Primethe adaptive immune system–Routinely present in small numbers–Immune response mounted against normalflora may later cross-react with pathogens–e.g. Mice raised in microbe-freeenvironments have under-developed immune systems
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