BIOL 3510 1st Edition Lecture 24 Outline of Last Lecture I Intro to Cell Cycle II G1 Phase III Control of S Phase IV Prophase V Prometaphase Outline of Current Lecture I Telophase II Body and Organ Regulation III Bcl2 IV Extracellular Signals Current Lecture Aurora kinase B detects tension and promotes kinetochore microtubule stability Anaphase begins with the separation of sister chromatids mediated by the anaphase promoting complex APC Sister chromatids are pulled to opposite spindle poles during anaphase A and anaphase B Sister chromatids are pulled to opposite spindle poles during anaphase A and anaphase B Telophase Mitotic spindle disassembles Nuclear envelope reassembles Chromosomes decondense Cytokinesis divides the cytoplasm and ends M phase In animal cells cytokinesis is mediated by a contractile ring actin and myosin filaments Forms perpendicular to the long axis of the spindle during anaphase Contractile ring assembly is mediated by the GTPase RhoA Cytokinesis is completed after telophase In plant cells the phragmoplast derived from the interpolar microtubules assembles the dividing cell wall These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute The rest of the organelles Mitochrondria and chloroplasts randomly partitioned during cytokinesis ER intact ER is cleaved in two during cytokinesis Golgi apparatus fragments and associates with spindle microtubules Other proteins randomly partitioned duing cytokinesis Body and organ size is regulated by Cell growth Cell division Cell death Cell necrosis is when injury causes cell swelling Apoptosis is programmed cell death Apoptotic cells are engulfed by phagocytic cells Apoptosis is mediated by the caspase family of proteases Cleavage activation of other caspases amplifies the apoptotic signal Bcl2 family proteins both promote and inhibit apoptosis Bax and Bak promote apoptosis by releasing cytochrome c from mitochondria Bcl2 inhibits apoptosis from inhibiting Bax and Bak Bad promotes apoptosis by blocking Bcl2 activity Cells in multicellular organisms receive extracellular signals that regulate cell survival division and growth 1 Survival factors promote cell survival by inhibiting apoptosis 2 Mitogens promote cell division 3 Growth factors promote cell growth an increase in cell size and mass Survival factors inhibit apoptosis Survival factors are released by target cells and mediate neuron survival Mitogens promote cell division by causing entry into S phase Examples of mitogens include plateletderived growth factors that promote growth repair and hepatocyte growth factor that promotes liver cell division Growth factors promote an increase in cell size and mass Other extracellular signals inhibit cell growth survival and or proliferation Myostatin inhibits the growth and proliferation of myoblasts
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