Thin descending and thin ascending segments, have thin epithelial membranes with no brush borders, few mitochondria, & minimal levels of metabolic activity.

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.

TLS Online TPP Program

#Id: 2964

#Unit 3. Fundamental Processes

The major role of ORC is to identify the origin to the Cdc6 and MCM proteins that control initiation and licensing.