Biological complexity: cell division chromosome actions (Introduction)

by David Turell , Monday, July 13, 2015, 18:48 (3421 days ago) @ David Turell

The chromosomes which are divided into two complete copies and pulled apart by microtubules have an enzyme which softens the outer membrane to make way for the division into two cells:-http://www.sciencedaily.com/releases/2015/07/150713113449.htm-"It is well known that microscopic cable-like structures, called microtubules, were involved in pulling chromosomes to opposite poles of the cell during the division process. "At this time, microtubules physically separate the chromosomes via their central kinetochores while other microtubules signal to the cortex of the cell where its equator is, i.e., where division will take place," Hickson explained. Furthermore until now, it was believed that the chromosomes only played a passive role: that they were pulled by the microtubules and didn't affect cytokinesis, but this is not the case.-"Initially working with the cells of fruit flies using powerful genetic tools and sophisticated microscopy, the research team discovered that chromosomes emit signals that influence the cortex of the cell to reinforce microtubule action. One of the key signals involved that the researchers identified acts via an enzyme complex -- a phosphatase known as Sds22-PP1 -- which is found at the kinetochores.-"They also demonstrated that this signaling pathway acts in human cells. "Such evolutionary conservation from flies to humans is expected for processes as fundamental as cell division," he explained. This is what makes fruit flies such a powerful system for helping us to understand human biology. "When chromosomes are segregated, they approach the membrane at the poles of the cell, and thanks to this enzyme's actions, this contributes to the softening of the polar membrane, facilitating the elongation of the cell and the ensuing division that occurs at the equator.'"-Comment: Remember, there is unstated further complexity in that all enzymes in these processes are giant complex molecules that speed the process.