A replication fork is initiated at the origin and then moves sequentially along DNA

TLS Online TPP Program

#Id: 2958

#Unit 3. Fundamental Processes

Reconciliation between this phenomenon and the use of ORCs is suggested by the discovery that environmental effects can influence the use of origins.

TLS Online TPP Program

#Id: 2959

#Unit 3. Fundamental Processes

A nucleus injected into a Xenopus egg can replicate only once unless the nuclear membrane is permeabilized to allow subsequent replication cycles

TLS Online TPP Program

#Id: 2960

#Unit 3. Fundamental Processes

ORC is a protein complex that is associated with yeast origins throughout the cell cycle.

TLS Online TPP Program

#Id: 2961

#Unit 3. Fundamental Processes

The key event in controlling replication is the behavior of the ORC complex at the origin.

Cdc6 protein is an unstable protein that is synthesized only in G1.

Cdc6 binds to ORC and allows MCM proteins.

Cdc6 binds to ORC and allows MCM proteins to bind.

Cdt1 facilitates MCM loading on origins

TLS Online TPP Program

#Id: 2962

#Unit 3. Fundamental Processes

When replication is initiated, Cdc6, and Cdt1 are displaced. The degradation of Cdc6 prevents reinitiation.

TLS Online TPP Program

#Id: 2963

#Unit 3. Fundamental Processes

The striking feature is that ORC remains bound at the origin through the entire cell Cycle.