Question

Kinesin 1 is highly processive motor, taking more than 100 steps (covering 1 μm along a microtubule) before dissociating, primarily because

A) it hydrolyzes ATP more rapidly than other motors.
B) one of its two heads is always attached in it hand-over-hand mechanism.
C) light chains at its nonmotor end attach to cargo vesicles.
D) its efficiency of converting ATP hydrolysis energy to useful work is 60-70%.
E) All are required for processivity.

Answer 1

The processivity of Kinesin 1 is primarily due to one of its two heads always being attached in a hand-over-hand mechanism.

Step-by-step explanation:

In order to explain why Kinesin 1 is highly processive and takes more than 100 steps before dissociating from a microtubule, we can look at the options provided. Option A, hydrolyzing ATP more rapidly than other motors, is not the reason for processivity. Option B, one of its two heads always remaining attached in a hand-over-hand mechanism, is the correct answer. The hand-over-hand mechanism ensures that at least one head is always attached to the microtubule, allowing the motor to continue moving. Option C, light chains at the nonmotor end attaching to cargo vesicles, is not related to the processivity of Kinesin 1. Option D, the efficiency of converting ATP hydrolysis energy to useful work being 60-70%, is also not the reason for processivity. Therefore, the correct answer is B) one of its two heads is always attached in a hand-over-hand mechanism.