Duplicate gene and its parental copy can subfunctionalize so that each carries out only some of the roles that the ancestral gene performed. 

Ex- a duplicate of the β-hemoglobin locus is expressed in the fetus. 

TLS Online TPP Program

#Id: 8846

#Section 3: Genetics, Cellular and Molecular Biology

In budding yeast CKI p27 = Sic1 in metazoans

TLS Online TPP Program

#Id: 8847

#Section 3: Genetics, Cellular and Molecular Biology

When CDK activity is low= helicases are loaded in G1

When CDK activity is high= helicases are activated in

S, G2 & M

TLS Online TPP Program

#Id: 8848

#Section 3: Genetics, Cellular and Molecular Biology

TLS Online TPP Program

#Id: 8849

#Section 3: Genetics, Cellular and Molecular Biology

Phosphorylation of MCM helicase activators by G1/S phase CDKs and S phase CDKs, prevents reloading of MCM helicases (ensuring that replication from each origin occurs only once during each cell cycle)

TLS Online TPP Program

#Id: 8850

#Section 3: Genetics, Cellular and Molecular Biology

Geminin 

a small protein,, that contributes to the inhibition of re-initiation at origins until cells complete a full cell cycle.

TLS Online TPP Program

#Id: 8851

#Section 3: Genetics, Cellular and Molecular Biology

Geminin is expressed in late G1; it binds to and inhibits Cdt1 preventing reloading of the MCM helicase.