microfilaments is the smallest of the cytoskeleton elements.
the smallest of the cytoskeleton elements is the?
microfilaments
prior to the work of jones et al., 2001, the cell wall was believed to be the deciding factor for many bacterial cell shapes, including rods and spirals. when studied, many misshapen bacteria were found to have mutations linked to development of a cell envelope. the cytoskeleton was once thought to be a feature only of eukaryotic cells, but homologues to all the major proteins of the eukaryotic cytoskeleton have been found in prokaryotes. harold erickson notes that before 1992, only eukaryotes were believed to have cytoskeleton components. however, research in the early '90s suggested that bacteria and archaea had homologues of actin and tubulin, and that these were the basis of eukaryotic microtubules and microfilaments. although the evolutionary relationships are so distant that they are not obvious from protein sequence comparisons alone, the similarity of their three-dimensional structures and similar functions in maintaining cell shape and polarity provides strong evidence that the eukaryotic and prokaryotic cytoskeletons are truly homologous. three laboratories independently discovered that ftsz, a protein already known as a key player in bacterial cytokinesis, had the "tubulin signature sequence" present in all α-, β-, and γ-tubulins. however, some structures in the bacterial cytoskeleton may not have been identified as of yet.
cytoskeleton
in addition to gyrating around their guiding field lines and bouncing back and forth between mirror points, trapped particles also drift slowly around earth, switching guiding field lines but staying at approximately the same distance (another adiabatic invariant is involved, "the second invariant"). this motion was mentioned earlier in connection with the ring current.
magnetosphere particle motion