Final answer:
Kinesin and dynein are major proteins associated with microtubules, facilitating intracellular transport of organelles and vesicles. The correct option is b.
Step-by-step explanation:
The major proteins kinesin and dynein isolated from a neural sample are functionally associated with microtubules. These proteins are motor proteins that utilize ATP hydrolysis to power intracellular motility, such as the transport of organelles and vesicles along microtubule tracks within cells.
Both kinesin and dynein carry different types of cargo, like vesicles formed at the trans Golgi face and vesicles containing neurotransmitters along the axons of neurons.
Kinesin is generally responsible for anterograde movement, transporting materials from the cell body towards the synapse, while dynein usually handles retrograde transport, moving materials from the synapse back to the cell body.
Together, they are essential for maintaining proper neuronal function and are integral components of the cytoskeleton, which provides structural support to the cell and plays a critical role in cell motility, including the movement of vesicles through the cell. The correct option is b.