In: Biology
1. What is the name of the protein subunits that compose microtubules?
2. What is the nucleating process for microtubules? (Name of protein and location in the cell)
3. How do microtubules grow and shrink?
4. What is dynamic stability? How is it regulated?
5. What function do microtubules play in the cell?
(Answers must one to two sentences please)
1. Microtubules are composed of tubulin protein. The microtubule subunit is tubulin heterodimer. ( alpha and beta tubulin, which forms protofilaments)
2. Microtubules are nucleated and organized by microtubule organizing centers in short MTOCs, like the centrosome found in the center of animal cells or the basal bodies found in cilia and flagella. Requirements for nucleation are Tubulin protein, Mg 2+ and GTP.
3. Microtubules grow at both the ends (positive and negative) by the polymerization of tubulin dimers (powered by the hydrolysis of GTP), and shrink at each end by the release of tubulin dimers (depolymerization).
4. Dynamic instability is a phenomenon in which individual microtubules alternate between growth and shrinkage. If the addition speed of GTP bound tubulin molecule is rapid than the rate of hydrolysis of GTP, the microtubule grows. And vice versa.
5. The functions of microtubules are determining positions of membrane enclosed organelles and involving in intracellular transport.