Lecture 15 Flashcards
What is necessary for initiation of replication?
Licensing factor
When is licensing factor present?
Prior to replication, but then it’s removed, inactivated or destroyed after
When is a new replication cycle possible?
When licensing factor re enters the nucleus after mitosis (the nuclear envelope must first break down)
What 2 things make up licensing factor?
CDC 6 and MCM 2, 3, and 5
Explain the process of Licensing factor step 1
ORC sits on ARS early in G1
LF step 2
CDC6 associates with the ORC
LF step 3 in late G1
CDt1 and MCM (minichromosome maintenance associate)
LF step 4
CDC6 gone in S phase
MCM still there
LF step 5
G2, only ORC and ARS remains
What are displaced by replication
CDC6, MCM2,3,5 and CDT1
What prevents reinitation of replication?
degradataion of CDC6
Post replication complex:
ORC bound to the origin
What MCM’s can only enter after mitosis is completed?
MCM 2, 3 and 5
The players in eukaryotic replication step 1
RPA binds
euk rep step 2
pol alpha/primase binds
euk rep step 3
RFC displaces pol alpha/primase
euk rep step 4
PCNA binds RFC
RFC/PCNA/ pol delt complex extends nascnet DNA and keeps going
euk rep step 5
RnaseH and MF1 remove the RNA primer
euk rep step 6
The gap is filled
euk rep step 7
the fragments are joined by ligase
Player 5
RFC/PCNA/Pol delta complex
Player 6
MF1 to extend the 5’-3’ exonuclease
Player 7
RNaseH removes the RNA primer
Player 8
DNA ligase seals the strands
Player 9
DNA helicase opens the double helix (MCMs)
When are active genes usually transcribed?
Early in S phase
When are late genes usually transcribed?
Late in S phase
Does early replication keep a gene active?
Obtaining the limiting transcription factors can help it stay active
Does an active gene promote early replication?
open chromatin conformation near an active gene allows the formation of replication complexes
More often it’s this reason
When is CDC6 synthesized?
only during G1
