BIOLOGY 2B03 Lecture Notes - Lecture 23: Dont, Nondisjunction, Cdc20
Document Summary
In multicellular systems, the cell cycle is highly monitored to ensure integrity of genome and to coordinate individual cell division within a large organism. Mammals most cells are in g0 and will. Never re-enter the cell cycle because they have differentiated and will cease by apoptosis, ex of cells: rbcs, nerve cells, muscle cells. Some cells will go to g0 temporarily and then enter g1 when they get the signal. G1 regulated by cdk2, cdk4, cdk6 and d-type cyclins. Completion of s cyclin a-cdk2, cyclin a-cdk1. In g0 there is not any cyclin or cdk expression; re-entry into cell cycle requires expression of d- type cyclins and cdk4 and cdk6. Mitogens (growth factors): signaling molecules that induce cell division by causing expression of. Restriction point (rp): regulatory checkpoint in which the cell cycle will proceed regardless of prese(cid:374)(cid:272)e of (cid:373)itoge(cid:374) (cid:862)poi(cid:374)t of (cid:374)o retur(cid:374)(cid:863) Two categories of gene expression patterns early response genes (erg) & late response genes (lrg)
