Myosin, kinesin, and dynein are important proteins governing internal transport. Myosin attached to organelles associates with actin microfilaments to enable the continuous flow of cytoplasm called cytoplasmic streaming.

Kinesins and dynein enable the movement of organelles along microtubules. They attach and move along microtubules. Most kinesins transport organelles from the center towards the periphery of the cell, anterograde transport. Dynein, and a few types of kinesins transport towards the cell center, retrograde transport.

Kinesin and dynein could definitely appear on the MCAT.