Mini Exam 10 Flashcards
Wendell Meredith Stanley
Discovered Tobacco Mosaic Virus (1935), first virologist
TMV Structure
Long, skinny protein tube (capsid!) shielding RNA genome
Virion
- infectious viral particle
- NOT A CELL (closer to parasite as it needs host to survive and multiply)
Genome of Viruses
DNA or RNA (in virion)
Capsid
- protein coat that surrounds a viral genome
- made of CAPSOMERES
Envelope
- membrane surrounding a virus
- originates from HOST
- NEED glycoproteins
- optional
Glycoproteins
-sugar-modified proteins embedded in membrane
- only in enveloped viruses
Influenza
- segmented RNA virus
- air droplet/aerosol
- spread from birds or swine (ZOONOTIC)
- high mutation rate & reassortment = evolves FAST, new vaccine every year
Virus Size Range
- 20- >200 nm oR 0.02 >0.2 micrometers
- can afford to be smaller bc it doesn’t have to do what living cells do; can pack light
Host
Cell that virus infects
Virus
- obligate INTRAcellular parasite
- SOME hijack host DNA replication and transcriptional machinery (DNA and Rretroviruses)
- ALL hijack host TRANSLATIONAL machinery (viruses don’t have ribosomes)
Genome Replication
Make more genome
Gene Expression
Make viral proteins
Baltimore System
Classification according to how mRNA is made
Genome types; segmented (reassortment)
- DNA or RNA
- circular or linear
- single or double stranded
- shore (6000 nts) or long (1,000,000 nts_
Viral Shapes
- Helical; filamentous, capsomere polymers build to form a HOLLOW TUBE; genome located in CENTER TUBE
- Polyhedral; icosahedron, capsomere polymers build to form a 20 SIDED shape; genome located in CENTER
- Spherical; enveloped, envelope can surround capsid; capsid can be a variety of shapes
- Complex; COMBINATION of shapes; often BACTERIOPHAGES
Phage Lytic Cycle
Phages cause bacteria lysis
- Attachment; phage binds to surface of cell; aka ADSORPTION PERIOD
- Entry; phage INJECTS DNA GENOME into cell
- Replication & Synthesis; phage DNA copied and transcription/translation produce phage PROTEINS
- Assembly; phage proteins and DNA combine to make NEW phages
- Lysis; cell busts open and new phages released!
Phage Lysogenetic Cycle
Viral genome recombines with host genome
- Prophage; genome INSERTED into host
- Excision; genome leads to LYTIC PHAGE
not ALL phages have this
Plaque
Clearing in bacterial lawn from phage lysis
Viral Growth Curve
of infective virions made over time;
Human Papillomavirus (HPV)
- DNA virus
- infects genital tract, mouth, throat (MUCOUS MEMBRANES) & skin; causes WARTS
- most common STI
- cervical cancer caused by 2 strains
- Pap smear
- HPV vaccine
