What are noncellular infectious agents?
viruses
True of False: Viruses are obligate intracellular parasites.
True
What does the structure of a virus consist of?
Nucleic acid core – DNA or RNA + Enzymes
Protein Capsid - capsomere units
Polyhedral, Helical, Spherical shapes
Envelope with tissue specific “spikes”
DNA viruses require?
Transcription and translation
RNA viruses require?
Only translation
What is the lytic virus lifecycle?
- attachment to cell receptors
- DNA or RNA penetration of cell membrane
- uses viral DNA or RNA to force the cell to replicate viruses while destroying cells DNA with enzymes.(biosynthesis)
- viruses mature inside of cell.
- cell bursts releasing viruses to attack surrounding cells.
What is the lysogenic virus lifecycle?
- Virus enters the cell and splices its DNA (prophage) into the cell’s DNA (integration) the cell becomes “lysogenic.”
- Stimulated at some later time into biosynthesis, it then forces the cell to produce viruses from the “prophage” (viral genetic code).
- The cell then enters lytic cycle and releases viruses to attack surrounding cells
What is two examples of a lysogenic virus?
Herpes and HIV
What are the four types of viruses?
bacteriophage
DNA viruses
RNA viruses
Retroviruses
Which viruses attack bacteria?
bacteriophage
Which viruses is used in gene transfers?
bacteriophage
Name some DNA animal viruses.
Herpes viruses
-oral and genital, chickenpox, shingles, mono
Papillomaviruses
-HPV and Warts
Which DNA viruses is associated with 95% of all cervical cancers?
papillomaviruses
Name some RNA animal viruses.
Picornavirus - small RNA virus -polio - neuromuscular disease -viral hepatitis - liver infection rhinovirus - common cold orthomyxoviruses -flu h1n1 swine flu Rhabdoviruses -rabies West Nile -encephalitis Ebola Virus -hemorrhagic fever
Name some RNA animal retroviruses.
HIV and AIDS
_________ is and RNA virus that converts into a lysogenic DNA virus using “reverse transcriptase” enzymes.
retrovirus
HIV Infection steps
- Virus enters blood through body fluid contact
- Virus attaches to and penetrates helper T-Lymphocytes that stimulate antibody production
- Reverse transcriptase enzymes convert RNA viral code into DNA
- DNA prophage is spliced into host cell DNA.
- Prophage may lie dormant or begin producing new viruses.
What are naked strands of RNA (no capsid) that cause plant diseases?
viroid
What are proteinaceous infectious particles?
prions
What does TSE stand for?
transmissible spongiform encephalopathies
What does prions cause?
TSE, neurodegenerative, causes enzyme changes in the brain
Who is the agent of mad cow?
prion
