Introduction:
Motor proteins convert chemical energy into directed movement along cytoskeletal tracks. The question asks which organelles are most directly associated with these motors during cargo transport inside cells.
Given Data / Assumptions:
- Kinesin and dynein move along microtubules; myosin moves along actin.
- Vesicles serve as primary cargo for long- and short-range transport.
- Organelles such as ER and Golgi are sources and destinations for vesicular traffic.
Concept / Approach:
Identify the cargo most routinely decorated with motor adaptors for directed movement between endomembrane compartments and the plasma membrane.
Step-by-Step Solution:
1) Vesicles bud from donor membranes and carry adaptors that recruit motors; strongly associated with kinesin/dynein/myosin.2) Smooth ER and Golgi are stations of origin/receipt but are not the typical discrete cargo units in motion.3) Plasma membrane is a destination for exocytosis; it is not transported by motors.4) Chloroplast relocation occurs in specialized contexts, but vesicle transport is the textbook, ubiquitous association.
Verification / Alternative check:
Live-cell imaging consistently shows fluorescent vesicles moving processively along microtubules/actin, validating vesicles as canonical motor-cargo.
Why Other Options Are Wrong:
a) ER is extensive but generally not a small, motile cargo unit.c) Membrane is a destination, not a moving organelle.d) Movement exists in plants but is context-dependent, not the primary association.e) Golgi depends on vesicle traffic; the vesicles themselves are the motor-linked cargo.
Common Pitfalls:
Confusing sites of membrane trafficking (ER/Golgi) with the principal transported units (vesicles).
Final Answer:
Vesicles.
Discussion & Comments