β-Carotene is the precursor of vitamin A1.
Oxidation at C-15 converts retinol to the aldehyde, retinal, and further oxidation produces retinoic acid, a hormone that regulates gene expression. 

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.

TLS Online TPP Program

#Id: 8852

#Section 3: Genetics, Cellular and Molecular Biology

Geminin contains a destruction box at its N-terminus that is recognized by APC/Ccdh1, causing it to be ubiquitinylated in late anaphase and degraded by proteasomes.

TLS Online TPP Program

#Id: 8853

#Section 3: Genetics, Cellular and Molecular Biology

Cohesins 

The protein ring complexes that establish linkages between sister chromatids