BIOB11H3 Lecture Notes - Lecture 10: G1 Phase, Sic1, Dna Replication
Document Summary
This drives the cell to mitosis: a mutant wee1 gene causes the cell to divide early since cdk is not inhibited during early g2. This results in smaller cells: a mutant cdc25 gene causes the cell not to divide but it will continually grow. Regulations of cdks: other mechanisms: cdk inhibitors block cdk activity and controls the cell cycle progression. Sic1 in budding yeast: controlled proteolysis is the degradation of cell cycle proteins via the ubiquitin- proteasome pathway. There are two classes of multi-subunit complexes that function as ubiquitin ligases (attaches the polyubiquitin chain to protein destined for degradation). Cell cycle checkpoints: cell cycle checkpoints are a system of proteins acting as sensors that recognize abnormalities/damage and trigger a temporary cell cycle arrest, this delay/arrest allows the cell to try and repair damage. If the damage is beyond repair, checkpoint signals can trigger controlled cell death (apoptosis) or convert the temporary arrest to permanent cell cycle arrest (senescence)
