BIO 201 Lecture Notes - Lecture 29: Immune System, Phagocytosis, Deoxyribonuclease
24 Apr 2017
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Not technically part of mitosis but is part of m phase! After chromatids (now daughter chromosomes) separate and spindle breaks down, a contractile ring forms. Contractile ring tightens divides parent cell into two daughter cells. No gaping hole since lipids like each other fill up hole. Experiment: treat cells at the end of anaphase with drugs: depolymerize actin using cytochalasin d (fungus toxin, result: no cytokinesis, inhibit myosin atpase activity using blebbistatin, result: no cytokinesis. Conclusion: actin and myosin are both required for cytokinesis! Actin and myosin mediate contraction of contractile ring cytokinesis. At beginning of cytokinesis, actin filaments run parallel around contractile ring in a random orientation. Double headed myosin anchored together at their tails find actin filaments oppositely oriented. Myosin is (+) end directed actin motor pull filament in opposite direction increase degree of overlap. Initial trigger for assembly of actin-myosin complex is unknown. Plant cell wall made of cellulose (secreted)
