topic 3b - lytic lifecycle

Question 1

what are the steps of the lytic lifecycle?

Answer 1

1: attachment/adhesion2: penetration/entry 3: synthesis 4: assembly (maturation) 5: release (lysis)

Question 2

the lysis step is also called

Answer 2

release

Question 3

the assembly step is also called

Answer 3

maturation

Question 4

in the synthesis step ds DNA how are genome copies made?

Answer 4

replication - DNA strand splits and each strand acts as a template for new DNA

Question 5

in the synthesis step ss RNA + sense how are genome copies made?

Answer 5

transcription -RNA genome acts as template for complementary - sense strand (using RNA dependent RNA transcriptase)

Question 6

what is RNA dependent RNA transcriptase?

Answer 6

uses RNA template to construct new complementary RNA

Question 7

in the synthesis step ss RNA - sense how are genome copies made?

Answer 7

transcription- genome acts as template for complementary + sense (need RNA dependent RNA transcriptase)

Question 8

in the synthesis step ss RNA - sense how are proteins made?

Answer 8

• 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

Question 9

in the synthesis step ss DNA how are genome copies made?

Answer 9

replication- ss DNA is used as template strand to form ds DNA

Question 10

in the synthesis step ds RNA how are genome copies made?

Answer 10

transcription - ds RNA splits and each strand uses RNA dependent RNA transcriptase to made complementary strand

Question 11

step 1: _______what ligand proteins are used by each virus type?

Answer 11

• attachment/ adhesion- proteins on host cell surface binds by ligand proteins: - phage: capsomeres on tip of tail fibers - naked: capsomeres - enveloped: peplomers

Question 12

what protein is needed for all virus types in this cycle

Answer 12

capsomeres

Question 13

what drug target affects step 1: attahment/adhesion? what does it do?

Answer 13

drug: attachment antagonist - prevents attachment to host cell

Question 14

step 2:________what are the processes with each virus type?

Answer 14

• 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

Question 15

what is endocytosis?what is uncoating?

Answer 15

host cell indents, breaks off creating vesicle of virions inside, and moves through cell -> followed by uncoating - uncoating: removal of capsomeres

Question 16

what is direct entry?

Answer 16

if capsomeres unfold in cell membrane they are touching a pore is formed & genetic material dribbles into cell cytoplasm

Question 17

what is the drug target in step 2: penetration/entry

Answer 17

drug target: uncoating inhibitors drug target: fusion inhibitors

Question 18

what 2 things are always made during step 3: synthesis

Answer 18

genome copies & proteins

Question 19

(-) sense RNA is readable or not readable?

Answer 19

not readable

Question 20

what drug targets are there in step 3: synthesis?

Answer 20

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

Question 21

step 4: assembly (maturation) - process - proteins -> capsomeres, peplomers, multiproteins

Answer 21

• 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

Question 22

what is the drug target for step 4: assembly (maturation)?

Answer 22

drug: protease inhibitor - prevents viral protein from being cut

Question 23

step 5: release (lysis) - process- virus types

Answer 23

• 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

Question 24

what is budding? what type of cell uses it and in what step?

Answer 24

• small vesicle is formed from the existing cell - it breaks off and is able to float away.- enveloped - step 5: release

Question 25

what is lyse?

Answer 25

host cell takes on water to break into smaller particles