BIOB11H3 Lecture Notes - Lecture 16: Sister Chromatids, Coiled Coil, Condensin
Document Summary
Biob11-l16: cell cycle ii (chromosome condensation & movement) Cytoskeleton disassembles; spindle apparatus forms; nuclear membrane breakdown. Chromosomes (cid:858)(cid:272)aptu(cid:396)ed(cid:859) (cid:271)y mts at (cid:272)e(cid:374)t(cid:396)o(cid:373)e(cid:396)es/ki(cid:374)eto(cid:272)ho(cid:396)es; (cid:271)egi(cid:374) (cid:373)ove(cid:373)e(cid:374)t to e(cid:395)uato(cid:396) Sister chromatids separate; begin poleward movement, poles also move apart. Each sister chromatid assembles a functional kinetochore at the centromere region. Start: g1/s cyclin + cdk triggers g1/s transition. Mpf: mitotic cyclin + cdk triggers g2/m transition. During s phase: dna replication must be initiated (replication licensing events, centrioles must be replicated. Targets for mpf for m phase to occur: nuclear membrane breaks down (lamins, chromosomes condense (condensin / cohesin, cytoskeleton undergoes dramatic reorganization (mt associated proteins) Induces disassembly of lamina release of chromatin. Chromatin now free to condense (able to form mitotic chromosome) Cohesin: 2 large smc coiled coil proteins (smc1,3) + several regulatory subunits (scc1,3) Wrap along axis after replication occurs & first part of prophase. Metaphase: cohesin remains only at centromere regions. Maintains sister chromatid cohesion until metaphase checkpoint has passed.
