Select all statements that are true in regards to the shrinkage and growth of mi
ID: 94476 • Letter: S
Question
Select all statements that are true in regards to the shrinkage and growth of microtubules. Microtubules with tubulin dimers containing GTP tend to stop growing. The tubulin at the free end of the microtubule occasionally hydrolyzes its GTP to GDP before the next tubulin dimer can be added due to the randomness of the chemical process. In a microtubule, tubulin dimers carrying GTP are bound more tightly to one another than polymerized tubulin dimers carrying GDP. The hydrolysis of GTP to GDP on the tubulin dimers stabilizes the microtubule.Explanation / Answer
The molecular basis of microtubule lattice instability derives from the hydrolysis of GTP to GDP in the lattice-bound state of -tubulin. It is a more stable part of its microtubule when it is GTP-bound; GDP-bound tubulin is apt to dissociate. Microtubules form primarily by addition of GTP-bound beta-tubulin at the (+) end, but after being added, the beta-tubulin molecules later hydrolyze their GTP, leaving them GDP-bound.
This GTP hydrolysis weakens the binding affinity of tubulin for adjacent molecules, thereby favoring depolymerization and resulting in the dynamic behavior of microtubules. In microtubules, GTP hydrolysis also results in the behavior known as dynamic instability, in which individual microtubules alternate between cycles of growth and shrinkage. Whether a microtubule grows or shrinks is determined by the rate of tubulin addition relative to the rate of GTP hydrolysis. As long as new GTP-bound tubulin molecules are added more rapidly than GTP is hydrolyzed, the microtubule retains a GTP cap at its plus end and microtubule growth continues. However, if the rate of polymerization slows, the GTP bound to tubulin at the plus end of the microtubule will be hydrolyzed to GDP. If this occurs, the GDP-bound tubulin will dissociate, resulting in rapid depolymerization and shrinkage of the microtubule.
In microtubules, GTP hydrolysis also results in the behavior known as dynamic instability, in which individual microtubules alternate between cycles of growth and shrinkage . Whether a microtubule grows or shrinks is determined by the rate of tubulin addition relative to the rate of GTP hydrolysis. As long as new GTP-bound tubulin molecules are added more rapidly than GTP is hydrolyzed, the microtubule retains a GTP cap at its plus end and microtubule growth continues. However, if the rate of polymerization slows, the GTP bound to tubulin at the plus end of the microtubule will be hydrolyzed to GDP. If this occurs, the GDP-bound tubulin will dissociate, resulting in rapid depolymerization and shrinkage of the microtubule.
All the options are correct.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.