BIOL 411 Lecture Notes - Lecture 19: Spindle Apparatus, Centromere, Sister Chromatids
Document Summary
Mitotic spindle: one end: centrosome (centriole is the center of the centrosome) aka mtoc- microtubule organizing center, the centrosome divides and organizes to either end of the cell. This determines polarity of cell division: microtubules originate from both centrosomes and attach to the kinetochores (protein attached to the centromeres of chromosomes) After replication, there are two copies of each sister chromatid pair (homologous chromosomes) Chromatids: there are 46 sister chromatid pairs, during mitosis: Interphase (g1, s, g2), sister chromatids are replicated and there are bi- polar centrosomes with spindle fibers coming out. Prophase: the chromosomes condense and attach to the spindle apparatus (dynamic tension- established by bi-polar attachment) and then align. Metaphase/anaphase transition: the main event in mitosis: **sister chromatid cohesion is established at replication (s phase)** Two m phases before new cells are born into g1. This helps them to determine whether or not they are homologs (occurs in prophase)
