Question

Which of the following would you expect to observe in an in vitro experimental mixture containing microtubules anchored by their minus ends to centrosomes, polystyrene beads with kinesin or dynein motors attached, and ATP?

A) movement of kinesin-attached beads along microtubules away from centrosomes
B) movement of dynein-attached beads along microtubules toward from centrosomes
C) movement of beads in either direction along a single microtubule
D) removal of ATP stopping all bead movement along microtubules
E) All would be expected.

Answer 1

In an in vitro experimental mixture containing anchored microtubules, beads with kinesin motors attached, and ATP, you would expect movement of kinesin-attached beads away from centrosomes along microtubules due to the motor protein's directionality.

Step-by-step explanation:

In an in vitro experimental mixture containing microtubules anchored by their minus ends to centrosomes, polystyrene beads with kinesin or dynein motors attached, and ATP, you would expect to observe the movement of kinesin-attached beads along microtubules away from centrosomes. Kinesin is a motor protein that moves towards the plus end of microtubules, so the beads attached to kinesin will move away from the centrosomes, which anchor the minus ends of microtubules.

Dynein, on the other hand, moves towards the minus end of microtubules. Therefore, you would not expect to see movement of dynein-attached beads along microtubules towards the centrosomes (option B is incorrect).

The beads in the experimental mixture can only move in one direction based on the motor proteins attached to them. Therefore, option C is incorrect. Additionally, removing ATP would indeed stop all bead movement along microtubules (option D is incorrect).

Hence, the correct answer is option A) movement of kinesin-attached beads along microtubules away from centrosomes.