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Astral microtubules anchor the spindle poles to the cell membrane. Microtubule polymerization is nucleated at the microtubule organizing center. An aster is a cellular structure shaped like a star, consisting of a centrosome and its associated microtubules during the early stages of mitosis in an animal cell.
The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells. [2] Fungi and plants lack centrosomes and therefore use other structures to organize their microtubules. [ 3 ] [ 4 ] Although the centrosome has a key role in efficient mitosis in animal cells, it is not essential in certain fly and flatworm species.
G 2 phase, Gap 2 phase, or Growth 2 phase, is the third subphase of interphase in the cell cycle directly preceding mitosis. It follows the successful completion of S phase, during which the cell’s DNA is replicated. G 2 phase ends with the onset of prophase, the first phase of mitosis in which the cell’s chromatin condenses into chromosomes.
Since the centrosome organizes the microtubules of a cell, it has to do with the formation of the mitotic spindle, polarity and, therefore, cell shape, as well as all other processes having to do with the mitotic spindle. [2] The centriole is the inner core of the centrosome, and its conformation is typically somewhat like that of spokes on a ...
The aster shouldn't be shown as sun rays; they should have the same appearance as the spindle microtubules (but shorter). The "Homologous chromosomes" label in prophase I should probably point to each of the pairs, the way "Sister chromatids" does in anaphase I. Typo in the anaphase I description: should be "chromosomes", not "chrmosomes".
Mitosis includes four phases: prophase, metaphase, anaphase, and telophase. Prophase is the initial phase when spindle fibers appear that function to move the chromosomes toward opposite poles. This spindle apparatus consists of microtubules, microfilaments and a complex network of various proteins.
Microtubules (MTs) are long proteic filaments, with asymmetric extremities: one end termed "minus" (-) end, relatively stable and close to the centrosome, and an end termed "plus" (+) end, with alternating phases of growth and retraction, exploring the center of the cell searching the chromosomes.
Microtubule and tubulin metrics [1]. Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm [2] and have an inner diameter between 11 and 15 nm. [3]