Bio181FinalExamGuide6 - Prophase 2 sister identical chromatids early mitotic spindle consist of microtubular fibers 2 extends between the 2 centrosomes

Prophase - 2 sister identical chromatids - early mitotic spindle consist of microtubular fibers - 2 extends between the 2 centrosomes - centrosome begin movement (migration) to the opposite poles of the cell (spindle) - nucleolus (-i) accumulation of RNA molecules in structural protein molecules - assembled large and small ribosomal subunits passing through nuclear cytosol. Prometaphase - microtubule from one pole attaches to kinotochore of one number of a chromatid pair, and one microtubule from opposite attaches to kinetochore of other member of pair - nonkinetochore microtubules - cross linking proteins between microtubules from opposite poles - alternating pulls by these microtubules toward opposite poles Metaphase - longest stage - metaphase – midplane - centromeres of all chromatid pairs are aligned on this plane - pulls toward opposite poles are precisely balanced Anaphase - shortest stage - centromeres divide, chromatid pairs all broken - mechanism of centromere division is not well understood - enzyme called “topoisomerase” causes centromeres to divide. Begins to reduce