BI110 Lecture Notes - Signal Transduction, Metastasis, Telomere
Document Summary
Cell cycle is controlled by complexes of cyclins with cyclin-dependent protein kinases (cdk: ckds only activated when combined with cyclin. Cdks: add phosphate groups to target proteins when activated by a cyclin. Different cyclin: cdk combinations regulate cell cycle transitions to different phases of the cycle together with checkpoints . Important internal controls create checkpoints: ensure that reactions of one stage are complete before cycle proceeds to next stage. These factors alter the activity of cyclin:cdk complexes. Based on surface receptors that recognize and bind signals: peptide hormones and growth factors, cell-surface molecules, molecules of the extacellular matrix. Binding triggers internal reactions (signal transduction pathways) that speed, slow, or stop cell division. Cellular senescence: loss of proliferative ability over time two candidates for responsibility of cellular senescence: dna damage, telomere shortening. Control of cell division is lost: cells divide continuously and uncontrollably, form rapidly growing mass of cells that interferes with body functions.
