Mitotic Spindle Beata Science Art Biology Diagrams The activity of spindle MAPs is essential for spindle formation and can be grouped into several activity classes . First, MT nucleation factors generate MTs from spatially discrete sites, termed MT organizing centers (MTOCs), that play a key role in constructing the mitotic spindle. (A) Features of the metaphase mitotic spindle. With their minus ends tethered at the spindle poles, microtubules extend either to the kinetochores of paired chromatids (kinetochore fibers), to the central spindle where they form an overlapping antiparallel array (interpolar microtubules), or away from the spindle towards the cell cortex (astral microtubules).
The mitotic spindle in yeast (A, left) is formed from spindle pole bodies (A, right) that are composed of five subcomplexes (B). (A, left) Immunofluoresence of a large-budded mitotic yeast cell showing SPBs marked by Spc42-GFP (green), microtubules (red), and DNA (blue) and electron micrograph (A, right) showing trilaminar ultrastructure. In all eukaryotes, morphogenesis of the microtubule cytoskeleton into a bipolar spindle is required for the faithful transmission of the genome to the two daughter cells during division. This process is facilitated by the intrinsic polarity and dynamic properties of microtubules and involves many proteins that modulate microtubule organization and stability. Recent work has begun to uncover
Molecular Biology of the Cell Biology Diagrams
Mitotic spindle formation begins as cells transition from interphase into mitosis. As the nuclear envelope breaks down in prophase, microtubules emanating from centrosomes undergo rapid polymerization and depolymerization, probing the intracellular space for chromosomes. This dynamic behavior, driven by tubulin instability, enables efficient A computational model for the formation of lamin-B mitotic spindle envelope and matrix. Interface Focus 4 , 20130063 (2014). Article PubMed PubMed Central Google Scholar The mitotic spindle is a microtubule-based assembly that separates the chromosomes during cell division. The life of a spindle starts with its formation by interactions between microtubules and chromosomes mediated by the microtubule-associated proteins and the kinetochore proteins during prometaphase and ends with chromosome segregation in
The completion of spindle formation is a crucial transition point in the cell cycle called the spindle assembly checkpoint. If chromosomes are not properly attached to the mitotic spindle by the time of this checkpoint, the onset of anaphase will be delayed. [36]
