Final answer:
Secretory vesicles are transported by motor proteins like kinesin and dynein, which use ATP to move along microtubule tracks in cells. This allows for the distribution and exocytosis of vesicular contents, essential for cell function and intercellular communication.
Step-by-step explanation:
Secretory vesicles are transported along microtubules in a cell by motor proteins such as kinesin and dynein. These proteins utilize ATP to facilitate movement, allowing for intracellular transport of organelles and vesicles. For example, vesicles containing secretory proteins move along the microtubule tracks to the plasma membrane, where they undergo exocytosis. Similarly, neurotransmitter vesicles are transported from the neuron cell body to the nerve endings along these tracks. In both cases, the vesicles are propelled by motor proteins that convert the chemical energy of ATP into mechanical work.
Kinesin proteins typically move cargo towards the plus end of microtubules, which is generally oriented towards the cell's periphery. On the other hand, dynein moves cargo towards the minus end, typically directed towards the cell center. The coordinated action of these motor proteins ensures that substances are accurately and efficiently transported within the cell, either for secretion outside of the cell via exocytosis or for use within different cell compartments.