The microtubule end with alpha-exposed subunits is the_____________ end, while the microtubule end with the beta-exposed subunits is the _____________ end.

Answer

The microtubule end with alpha-exposed subunits is the negative end, while the microtubule end with the beta-exposed subunits is the positive end.

Explanation

Tubulin subunits are always linked in the same direction. Hence, microtubules have two distinct ends called the positive end and the negative end. On the negative end, the alpha tubulin is exposed and on the positive end, the beta tubulin is exposed. This polarity is very important for the biological function of these microtubules as the beta subunits of one tubulin dimer contact the alpha subunits of the next dimer.