Virus and Phage 1 Flashcards
Explain some differences between viruses and living organisms
Viruses: acellular, rely on host for energy
Living: can generate energy from the environment, cells can increase and grow
Viruses of prokaryotes typically inject ___ into host cells
Genetic materials
What is the primary difference between lytic viruses and temperate viruses?
Temperate viruses induce the lytic cycle
What unit is used to count bacteria?
Colony forming units (CFU)
Describe some DIRECT approaches to enumerating virus particles
Electron microscope
Viral genome via quantitative PCR
Describe some INDIRECT approaches to enumerating virus particles
Hemoglutination assay Plaque assay (LD50)
What two components do the simplest form of viruses have?
What are these viruses called?
Nucleic acid genome + protein shell (capsid)
Nucleocapsids
(T/F) The protein shell of viruses are assembled from a few individual protein subunits
False!
Formed from many (hundreds) individual protein subunits
The capsid head is formed from (#) protein subunits, which assemble into ___ and ___ (think soccer ball)
One
Hexagons
Pentagons
Inside the capsid head the ___ looks like a thread on a spool
dsDNA
What are the two general types of virions?
Non-enveloped
Enveloped
(T/F) Enveloped viruses have plasma membranes composed of lipids
True!
(T/F) Viral genomes can be RNA or DNA
True!
(T/F) Viral genomes can only be single-stranded (ss) nucleic acids
False!
Can be single stranded (ss) or double stranded (ds)
(T/F) Viral genes may be on a single nucleic acid molecule OR divided among multiple nucleic acid molecules
True!
(T/F) Viral genomes do not vary greatly in size
False!
They can be anywhere from 4 kb long up to 1.2 mbp long
What are the 6 minimum functions that a virus must do to reproduce?
- bind to host cell
- induce genome into host cell
- get viral genome replicated
- get viral proteins expressed
- assemble new visions
- get progeny virus to exit cell
How do DNA viruses replicate their genome?
How do RNA?
They have proteins that hijack the host DNA polymerase
They provide their own protein to replicate the RNA
How do DNA viruses get their viral proteins expressed?
How do RNA?
They often use host RNA polymerase to synthesize mRNA
They provide their own protein to synthesize mRNAs
(T/F) During translations, viral mRNAs are translated by host ribosomes
True!
What are two ways that virus progeny can leave the host cell?
- lysing of the cell
2. budding through the hosts’ plasma membrane
