Chapter 12 Lecture notes

Towards the pole from which the microtubule extends

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Unformatted text preview: ter: radial array of short microtubules that a^ach to the plasma membrane Sister [email protected] Nonkinetochore Microtubules: func+on in elonga+ng the whole cell during anaphase Metaphase Plate Kinetochores: a structure of proteins associated with specific sec+ons of chromosomal DNA at each centromere Kinetochore Microtubules: a^ach to kinetochores Moves a chromosome towards the pole from which the microtubule extends MitoAc spindle is composed of: 1.  Centrosomes 2.  Spindle microtubules (kinetochore and nonkine+chore microtubules) Centrosomes: Duplicate during interphase (S phase) in animal cell and move apart during mitosis (prophase and prometaphase). Spindle Microtubules: Growth Shrinkage G2 of Interphase Prophase •  In animal cells, each centrosome contains two centrioles •  Chromosomes and centrosomes are duplicated in S phase •  Chroma+n fibers condense •  •  Centrosomes begin to move away from each other •  Nuclear envelope fragments •  Microtubules invade the nuclear area Prometaphase •  •  Nonkinetochore microtubules interact with those of the opposite spindle Stages of Mitosis: Key Points Metaphase Anaphase •  Longest stage in mitosis – lasts 20 minutes •  Chromosomes convene on the metaphase plate •  Kinetochores of sister chroma+ds are a^ached to kinetochore microtubules •  Shortest stage in mitosis – lasts just a few minutes •  •  Each chroma+d becomes a full ­fledged chromosome •  Cells elongate as the nonkinetochore microtubules lengthen •  Nuclear envelope forms •  Mitosis – division of one nucleus into two nuclei is complete Telophase Cytokinesis •  Division of...
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This document was uploaded on 02/10/2014.

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