Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Microbiology
Chapter 13
| Question | Answer |
|---|---|
| Characteristics of Viruses | *cause infections of humans, animals, plants, and bacteria *cannot carry out any metabolic pathway *cannot grow or respond to the environment*cannot reproduce independently *use the host cell machinery to increase their numbers |
| Extracellular State of Virus | protein coat (capsid) surrounding nucleic acid = nucleocapsid *some virions have a phospholipid envelope *the outermost layer of the virion is recognized by host cells |
| Intracellular State | when the virus is inside the host, the capsid is removed and the virus exists as a nucleic acid |
| What are the Genetic Material of Viruses | *may be DNA or RNA, but never both together *can be double stranded or single stranded nucleic acid *may be linear and composed of several segments or single and circular *much smaller in size than the nucleic acids of cells |
| Hosts of Viruses | *A virus infects only particular host cells |
| How does the Virsu determine the host range | Viral surface proteins (glycoproteins) interact with complementary proteins or glycoproteins on host cell surface. |
| Narrow host range | virus only infects particular kind of cell in a particular host |
| Broad host range | virus infects many kinds of cells in different hosts |
| Caspid composed of.. | proteinaceous subunits called capsomeres |
| Capsid Morphology | protect viral nucleic acid and help attachment of the virus to host cells |
| The Viral Envelope | *acquired from host cell membrane during viral replication or release from host cell *composed of phospholipid bilayer and proteins (e.g. glycoprotein spikes) |
| Function of the viral envelope's proteins and glycoproteins | host cell recognition and attachment |
| Viral Replication | *dependent on host cell machinery *viral replication cycle usually results in death and lysis of host cell → lytic replication |
| Stages of lytic replication cycle | 1.Attachment using tail fibers 2.Entry 3.Synthesis 4.Assembly 5.Release |
| Assembly of new bacteriophages | base, Tail, Sheath, DNA, Capsid, mature heads, tail fibers, mature virion |
| Lysogeny | infected host cells grow and reproduce normally for generations before they lyse |
| Temperate prophages | phage DNA is incorporated into host cell chromosome |
| Lysogenic conversion | results when phages carry genes that alter phenotype of a bacterium |
| Replication of Animal Viruses(same as bacteriophages replication) | base, Tail, Sheath, DNA, Capsid, mature heads, tail fibers, mature virion |
| How do animal virus differ from bacteriophages | *Presence of envelope around some viruses *Eukaryotic nature of animal cells *Lack of cell wall in animal cells |
| How do animal viruses attach | *animal viruses do not have tails or tail fibers *have glycoprotein spikes or other attachment molecules |
| Three mechanisms of entry of animal viruses | *Direct penetration *Membrane fusion *Endocytosis |
| Direct penetration | virus attaches to host cell receptors and injects its genome into the cell |
| Membrane fusion | virus gylcoproteins attach to host cell receptors, envelope fuses with host cell membrane, capsid enters and then is uncoated to release the viral genome into the host cell |
| Endocytosis | host cell cytoplasmic membrane wraps around virus and brings it inside, the capsid is uncoated and the viral genome is released into the host cell |
| Replication of Animal Viruses | *each type of animal virus requires different strategy depending on its nucleic acid *DNA viruses often enter the nucleus *RNA viruses often replicated in the cytoplasm |
| Assembly of Animal viruses occurs where? | *most DNA viruses assemble in the nucleus *most RNA viruses develop solely in the cytoplasm |
| What does the number of viruses produced depend on? | the type of virus and size and initial health of the host cell |
| what types of viruses cause persistent infection? | enveloped viruses |
| what are naked viruses released by? | exocytosis or lysis |
| What is latency of animal viruses? | *animal viruses remain dormant in host cells, may be prolonged for years with no viral activity, signs, or symptoms *some don't become incorporated into host chromosome |
| What happens when a provirus is incorporated into the host DNA? | *condition is permanent, it becomes part of host’s chromosome |
| What are the different ways to culture viruses in the lab? | *in whole organisms E.g. bacteria, plants, and animals *in embryonated chicken eggs *in cell (tissue) culture |
| What are the inoculation shites for the culture of viruses in embryonated chicken eggs? | *chorioallantoic membrane *chorioallantois *embryo *amnion *yolk sac |
| Characteristic of Viroids | *very small, circular RNAs that are infectious and pathogenic in plants *similar to RNA viruses, but lack capsid |
| Characteristics of Prions | *proteinaceous infectious agents *can contain cellular PrP protiein *can contain Prion PrP *normally, nearby proteins and polysaccharides force PrP into cellular shape *PrP mutations result from formation of prion Pr |
| Cellular PrP protein | *made by all mammals *normal structure with alpha helices |
| Prion PrP | *disease-causing form with beta pleated sheets *changes shape of cellular PrP so it becomes prion PrP |
| what do all prion diseases involve? | fatal neurological degeneration, deposition of fibrils in brain, and loss of brain matter |
| What forms in the brain as a result of prions? | large vacuoles form; characteristic spongy appearance *spongiform encephalopathies (BSE, CJD, kuru) |
| how are prions destroyed? | only by incineration or autoclaving in 1N NaOH |
| example of prion disease shown in class? | scrapie; infected the brain of a sheep |
| how is the prion disease transmitted? | ingestion of infected tissue, contact with mucous membrane or broken skin with infected tissues, transplant of infected tissue |
Created by:
izis
Popular Biology sets