Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
52 Cards in this Set
- Front
- Back
|
Basic structure of a virus |
nucleic acid core surrounded by capsid protein -can be DNA or RNA -circular or linear - Single or Dounble stranded - RNA viruses can come in more than 1 pc. Classified by genome - RNA viruses -DNA viruses - retroviruses (RNA-HIV-2 nucleic acids) |
|
|
Virion |
inactive virus particle outside the cell -not alive or dead jut active or inactive form a protein sheath (capsid) around nucleic acid core |
|
|
Specialized enzymes Reverse transcriptase |
stored in nucleic acid core in protein
reverse transcriptase in not found in host |
|
|
envelope (membrane) |
Many animal viruses have additional layer around virus from hosts cell membrane |
|
|
Viral Hosts |
obligate intracellular parasites - have to get into cell in order to replicate host range - types of organisms infected tissue tropism- - inside host virus only infect certain tissues *no universal virus* dormant or latent -chicken pox later into shingles More kinds of viruses (nonliving) exist than living organisms |
|
|
Viral Replication |
infected virus=set of instructions in nucleic acid viral genome tricks host into reproducing virus -except retroviruses can ONLY reproduce in cells lack ribosomes and enzymes for protein and nucleic acid synthesis hijacks cells transcription and translation result-assembly and release of new viruses in couple of ways |
|
|
Viral Shapes |
most viruses come in two simple shapes some viruses are complex enveloped viruses are POLYMORPHIC -many dependent upon host DNA |
|
|
Icosahedron |
3 different repeating proteins most animal viruses most efficient arrangement like a soccer ball |
|
|
Helical |
rod like shape |
|
|
Bacteriophage |
binal symmetry like a robot insect |
|
|
Pox viruses |
multilayered capsids |
|
|
Viral Genomes |
vary in type of nucleic acid and number of strands Most RNA viruses are single stranded -copied in cytoplasm Most DNA are double stranded - copied in nucleus of eukaryotic cell Replications in cytosol is error-prone=high rates of mutation=difficult to target immune system and drugs/vaccines |
|
|
RNA viruses |
positive strand virus -mRNA enters cell negative strand virus -genome is complimentary to viral mRNA retroviruses -reverse transcriptase -RNA-enzyme-DNA-into our genome |
|
|
Bacteriophage |
viruses infect ONLY bacteria E. Coli viruses have been found in archaea -differ from bacterial virus - characterization in early stages |
|
|
Attachment/Adsoprtion |
start virus attaches to a certain part of host |
|
|
Penetration/ Injection |
T4 pierces into cell wall to inject viral genome viruses NEED to be IN the cell to replicate |
|
|
Synthesis |
phage takes over cell's replication and protein synthesis enzymes to synthesize viral components |
|
|
Assembly |
assembly of viral components |
|
|
Release |
mature virus is released by: 1. enzyme lysing host 2. budding through host cell wall -if the virus can not escape the cell then it can NOT infect more of the host |
|
|
Eclipse period |
length of time between attachment to the release |
|
|
Lytic cycle |
virus lyses the infected host cell -virulent/lytic phages |
|
|
Lysogenic Cycle |
viruses do not kill infected cell immediately prophage=virus nucleic acid integrated into host cell genome integration allows virus to be replicated along with the host cells DNA as the host divides RESULT-bacteria (2)-bacteria (4) and all have a viral infection |
|
|
Binal Phage lambda of E Coli |
best studied particle phage infects cell-early events determine is the virus is lytic or lysogenic induction during stress -prophage excised and begins lytic cycle -requires turning on the gene expression necessary for lytic cycle |
|
|
Phage Conversion |
Phenotype or characteristics of the lysogenic bacterium is altered by the prophage |
|
|
Vibrio Cholerae |
phage conversion -lysogenic phage introduced a gene coding for cholera toxin -gene incorporated into host genome -converts harmless bacteria into disease-causing form Cholera w/o phage is harmless |
|
|
HIV |
causes AIDS originated in Africa some are resistant (variable resistance b/c small pox) -exposed repeatedly -hiv but not aids -progress rapidly hiv-aids-death in 1 year symptoms after 8-10 years latent period |
|
|
Smallpox |
killed billions if you did NOT have CCR5 receptor you were resistant to smallpox and HIV |
|
|
CD4+ |
targeted by HIV w/o cell immune system ineffective provirus infects CD4+ and in genome of macrophages |
|
|
HIV Testing |
tests for presence of antibodies against HIV further testing of breaking open cells confirms |
|
|
Spread of AIDS |
carriers-no clinical symptoms-are infectious infectious through latent period mutation overcomes the immune system and AIDS begins |
|
|
Attachment |
virus attacks CD4+ cells Viral gp120 attaches to CD4+ protein and cells Coreceptors like CCR5 affect likelihood of entry |
|
|
Entry |
through fusion pore |
|
|
Replication |
reverse transcriptase converts RNA to DNA DNA incorporated into host genome Variable period of dormancy |
|
|
Assembly |
making many copies of virus |
|
|
Release |
new viruses exit by BUDDING couple at a time with some membrane so the cell stays alive |
|
|
AIDS Treatment |
~32 drugs used in treatment none are 100% effective -viral entry -genome replication -integration of viral DNA -maturation of HIV proteins |
|
|
Reverse transcriptase inhibitors |
AZT-1st drug licensed clinical use Selective for HIV not in our cells |
|
|
Protease inhibitors |
target polyprotein that is necessary for viral replication and assembly rational drug design-started with protease enzyme then for drug |
|
|
Blocking viral entry |
fusion inhibitor blocks fusion of viral envelope with plasma membrane of a target cell |
|
|
Integrase inhibitors |
approved drug that targets viral integrase protein |
|
|
Combination therapy |
combination of drugs has entirely eliminated HIV from patients HAART cut death rate by 3/4 therapy stops-virus levels rise again |
|
|
Influenza |
started by the Spanish flu most lethal viruses in human history flu viruses are enveloped animal viruses -type A serious -type B and C mild human infections Subtypes differ in protein spikes -H-aids in viral entry -N-Aids in viral exit |
|
|
H & N proteins |
molecules can accumulate mutations-reason for yearly flu shots flu viruses can undergo genetic recombination when 2 subtypes infect the same cell |
|
|
antigetic shifts |
H antigen and N antigen caused epidemics -spanish flu~50 million (20-40) -asian flu~2 million Hong Kong flu~70,000 |
|
|
Influenza Viral Hosts |
ducks, chickens, pigs typically in South East Asia Hong Kong arose from duck/human recombination |
|
|
Emerging Viruses |
viruses that are extending their host range often deadly to new host considerable threat in aviation age |
|
|
Hantavirus |
causes deadly pneumonia natural host: deer mice yosemite easy to kill host |
|
|
Ebola Virus |
-severe hemorrhagic fever -one of most lethal infections -unkown host |
|
|
SARS |
Severe Acute Respiratory Syndrome -caused by coronavirus -host is civet (weasel-like) -mutations rate low -SARS vaccine currently being developed |
|
|
Viruses and Cancers |
viruses contribute up to 15% of cancers -can alter growth properties of cells -trigger expression of onconogens -disrupt and control cell cycle HPV vaccine to prevent cancer |
|
|
Prions |
"Proteinaceous infection particles" -transmissible spongiform encephalopathies (TSE) -mad cow disease (BSE) -Creutzfeldt-Jacob disease in humans (CJD) host has normal prion proteins (PrPc) -misfolded proteins cause disease(PrPsc) |
|
|
Viroids |
tiny "naked" molecules of circular RNA cause disease in plants killed 10 mill in Phillippines autonomously replicate -info appears to be in 3D structure not RNA |
