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Viruses
Test #1
| Question | Answer |
|---|---|
| General Characteristics of Viruses | -very small 10-14nm |
| What is an intracellular parasite? | -can only reproduce within living host |
| Discuss host specificity. | -most cells are host-specific (infected only one or a few species of hosts) Example: HIV |
| Describe the structure of viruses. | -individual units of virus are called virions or particles |
| What are viroids? | -infectious particles, made of RNA only; can infect plants |
| What are prions? | -infectious particles, made of protein only; can infect animals |
| General Characteristics of Viruses | -considered to be “semi-living”→ they have some of the characteristics of life: NOT made up of cells; are much less complex (macromolecules); are able to reproduce only with considerable help from the host; have NO metabolism |
| General Characteristics of Viruses | -are obligate intracellular parasites (can only reproduce w/in living hosts); will not grow on artificial media |
| General Characteristics of Viruses | -do exist outside of host cells |
| General Characteristics of Viruses | -have a high mutation rate |
| Discuss tissue specificity. | -most viruses are tissue-specific |
| Host Range | all of the host species that a pathogen can infect |
| Structure of Viruses | -individual units of virus are called virions or particles |
| Structure of Viruses | -every virus has a core of nucleic acid (genetic material)→either DNA or RNA→ never both; either single or double stranded |
| Structure of Viruses | -every virus has a coat of protein(capsid) around the nucleic acid |
| Structure of Viruses | -some viruses have an outer envelop of fat & protein surrounding the protein→ the envelop is at least partially derived from the host cell membrane |
| What are bacteriophages? | -viruses that infect bacteria (aka phage)→ often used in research for studies on genetics, & learning about viruses because they are easy to grow |
| Latent Viral Infection | -the virus remains in the host without producing symptoms & there is little or no detectable virus until reactivated later Examples: all herpes viruses |
| Persistent Viral Infections | -the viruses reproduce but slowly &over a very long period of time; gradual increase in the # of viruses over a long period of time Examples: AID dementia caused by HIV |
| Relationship between Viruses and Cancer | -some human (and many animal) cancers are known to be caused by viruses called oncogenic viruses Examples: Leukemia |
| Relationship between Viruses and Cancer | -development of cancer also involves oncogenes & tumor suppressor genes & immune deficiency |
| Body Defenses against viral infections | -immunization: best way of preventing infections; interferon’s: protein messengers produced by virally infected cells to alert neighboring cells to produce anti-viral proteins; antibodies, T cells |
Created by:
lisaanne11