Section 2 pt 2 B Flashcards
Phage λ: After infection and circularization of the DNA genes ____ and _____ are expressed
N and cro
Phage λ: N and cro allows expression of gene ____
cII
Phage λ: if lysis, activates expression of ____ and __ genes
structure & lysis
Phage λ: if lysogeny: expresses genes ___ and ___
cI and int
Immediately after infection, only the cro and N genes get transcribed because only the ___ and ____ are bound by the host’s RNA pol
PL and PR
transcription stops after cro and N because of the terminators
TL1 and TR1
After N and Cro get translated, they bind to DNA and RNA pol at ___ sites
nut
nut sites are named for N utilization as N is a ____ _______ protein
anti-terminator
N is an anti-terminator so it leads to continuous RNA pol transcription past terminator to make __ gene
cll
If cll is acted upon by proteases and inactivated, it means the cell is well growing and active and the _____ cycle occurs
lytic
If cll is not inactivated, It means the cell is in poor state, and the _____ cycle occurs
lysogenic
When cll gets degraded, activates replication and lysis genes and inhibits cl
early lytic genes: (2)
1- DNA replication genes “rolling circle replication” that makes linear concatemers
2- another anti terminator Q: activates transcription of late Luton genes (works PR’)
Late lytic genes: (3)
heads, tails, lysis
Rolling cycle replication makes concatermer by:
DNA replication makes copies of DNA with small gaps at the end, those are later recombined to form concatermer
Lambda packages one genome length into the head between ___ sites of the concatermer called ___ ____ packaging
cos
Pac site packaging
packaging done by terminase enzyme complex through: (4 steps)
1- binds to DNA
2- recognizes cos site
3- cuts it at cos
4- uses ATP to pomp that DNA inside until next cos site
Lysis of the cell needs to be carefully controlled to ensure that the cell doesn’t lyse before the new viruses are assembled, this is done by the genes ___, _____ and _____ that act as molecular clocks
S, R, Rz/Rz1
S: holin:
Puts a hole in the CM
R: endolysin:
degrades peptidoglycan
Rz/Rz1:
span from inner to outer membrane to disrupt outer membrane
____ protein accumulates in the CM overtime and eventually reaches a critical concentration (S-105 more than S-107), changes confirmation, membrane depolarizes and it DISRUPTS the PMF, makes hole in CM
holin
lambda ____ protein is a transglycolyase that breaks bonds between sugar chains in peptidoglycan
endolysin
__ is In the IM and __ is a lipoprotein attached to the inner side of the OM
After holin opens the IM, the lysin can get into the periplasm to degrease the peptidoglycan and then Rz and Rz1 interact to disrupt OM
Rz
Rz1 is a lipoprotein
