EXAM 4: Viruses

lytic vs lysogenic

lytic: phage DNA into chromosome -> new phages made -> phages lyse cell
lysogenic: phage DNA into chromosome until stressor excises it

what is phage DNA called while it is dormant in the lysogenic cycle

prophage

how does transduction work

when phage lyses, it takes some bacterial DNA instead of phage DNA and then when it infects bacteria, it adds bacterial DNA, not viral DNA

how does specialized transduction differ from generalized transduction

viral DNA goes with phage, as well as bacterial chromosome regions NEXT to prophage

difference between viruses and viroids/virusoids

viroids and virusoids do not have protein coat, only RNA

difference between viroids and virusoids

virusoids cannot replicate autonomously - needs a helper virus

virion

complete virus particle - genome, capsid, maybe envelope

typical size of viruses

10-100 nm

exceptions to virus size and why are they bigger

CroV and Mimivirus — require extra machinery

what must negative sense viruses carry

RNA polymerase

what must retroviruses carry

reverse transcriptase

viruses are obligate intracellular ______

parasites

three types of capsid shapes

helical - spiral arrangement with genome inside of proteins
icosahedral - 20-sided polygon with genome inside
complex - not one specific shape

poxvirus is complex in the sense that _______, whereas Bacteriophage T-4 is complex in the sense that ______

has more complex internal structures and no distinct symmetry
it is binal — icosahedral head, helical tail

two types of polymers that make up the faces of an icosahedral virus

pentamer or hexamer

peplomer

spike on virus that aids in attatchment

primary membrane proteins of influenza

hemagglutinin and neuraminidase

identification of influenza

type of hemagglutinin and neuraminidase

relationship between hemagglutinin and neuraminidase

neuraminidase cleaves hemagglutinin so it stops attachment and allows invasion

how does Tamiflu work

prevents neuraminidase from doing its job, cannot cleave hemagglutinin

why would a virion contain an enzyme

function in nucleic acid replication