topic 3b - lytic lifecycle Flashcards
what are the steps of the lytic lifecycle?
1: attachment/adhesion2: penetration/entry 3: synthesis 4: assembly (maturation) 5: release (lysis)
the lysis step is also called
release
the assembly step is also called
maturation
in the synthesis step ds DNA how are genome copies made?
replication - DNA strand splits and each strand acts as a template for new DNA
in the synthesis step ss RNA + sense how are genome copies made?
transcription -RNA genome acts as template for complementary - sense strand (using RNA dependent RNA transcriptase)
what is RNA dependent RNA transcriptase?
uses RNA template to construct new complementary RNA
in the synthesis step ss RNA - sense how are genome copies made?
transcription- genome acts as template for complementary + sense (need RNA dependent RNA transcriptase)
in the synthesis step ss RNA - sense how are proteins made?
- proteins cant be translated from the og strand since it is - sense and can’t be read. - proteins are translated from the + sense strand in the first ds RNA set
in the synthesis step ss DNA how are genome copies made?
replication- ss DNA is used as template strand to form ds DNA
in the synthesis step ds RNA how are genome copies made?
transcription - ds RNA splits and each strand uses RNA dependent RNA transcriptase to made complementary strand
step 1: _______what ligand proteins are used by each virus type?
- attachment/ adhesion- proteins on host cell surface binds by ligand proteins: - phage: capsomeres on tip of tail fibers - naked: capsomeres - enveloped: peplomers
what protein is needed for all virus types in this cycle
capsomeres
what drug target affects step 1: attahment/adhesion? what does it do?
drug: attachment antagonist - prevents attachment to host cell
step 2:________what are the processes with each virus type?
- penetration/entry
- phage: lysozyme and contraction of tail
- naked: endocytosis w/ uncoating & direct entry
- enveloped: endocytosis w/ uncoating & direct entry & fusion of cell membrane and envelope
what is endocytosis?what is uncoating?
host cell indents, breaks off creating vesicle of virions inside, and moves through cell -> followed by uncoating - uncoating: removal of capsomeres
what is direct entry?
if capsomeres unfold in cell membrane they are touching a pore is formed & genetic material dribbles into cell cytoplasm
what is the drug target in step 2: penetration/entry
drug target: uncoating inhibitors drug target: fusion inhibitors
what 2 things are always made during step 3: synthesis
genome copies & proteins
(-) sense RNA is readable or not readable?
not readable
what drug targets are there in step 3: synthesis?
drug: RNA dependent RNA transcriptase blockers - RNA wouldn’t be able to trnascribe and create genome copies drug: nucleotide analogues - “fake” nucleotide drugs replace nucleotides in DNA -> virus causes mistakes and uses the fake instead
step 4: assembly (maturation) - process - proteins -> capsomeres, peplomers, multiproteins
- viral parts are put together - capsomeres -> form capsid (enclosing genetic info) -> now nucleocapsid- enveloped: peplomers go to membrane - if multiprotein made: cut proteins apart & fold
what is the drug target for step 4: assembly (maturation)?
drug: protease inhibitor - prevents viral protein from being cut
step 5: release (lysis) - process- virus types
- cell ruptures to release virus particles - phages: host cell explodes (lysozyme -> digests peptidoglycan cell wall) - naked: host cell takes on water to lyse & exocytosis - enveloped: viruses must bud out of a membrane to gain envelope and peplomers
what is budding? what type of cell uses it and in what step?
- small vesicle is formed from the existing cell - it breaks off and is able to float away.- enveloped - step 5: release
what is lyse?
host cell takes on water to break into smaller particles
