The current model for the nucleation of microtubules is that a helical array of gamma-tubulin subunit forms an open,ring-shaped template on which the first row of alphabeta-tubulin dimers assembles.How does this model account for the polarity of microtubules?
A)Only the alpha-tubulin of a heterodimer can bind to the ring of gamma-subunits.
B)Only the beta-tubulin of a heterodimer can bind to the ring of gamma-subunits.
C)The ring structure straightens out the microtubule.
D)The ring structure interacts with a homodimer instead of a heterodimer.
E)Only the alpha-tubulin of a heterodimer can bind to the ring of gamma-subunits.and the ring structure straightens out the microtubule.

Question

Quizplus · Accepted Answer

Only the alpha-tubulin of a heterodimer can bind to the ring of gamma-subunits. This ensures that the microtubule grows in the correct direction, with the alpha-tubulin subunits at the plus end and the beta-tubulin subunits at the minus end.

The Current Model for the Nucleation of Microtubules Is That