Using time-lapse fluorescence microscopy, you have recorded the transport of fluorescently labeled mitochondria in a region of an axon in a fruit-fly larva; you have plotted the results in the following graph, in which the vertical axis is time (from the top to the bottom), the horizontal axis is the position along the axon, and each trace represents one mitochondrion. Is the retrograde transport or the anterograde transport of mitochondria faster in these axons? Does the trace indicated by an asterisk correspond to a mitochondrion that was transported by a dynein or a kinesin?
A) Anterograde; kinesin
B) Anterograde; dynein
C) Retrograde; kinesin
D) Retrograde; dynein

Question

Using time-lapse fluorescence microscopy, you have recorded the transport of fluorescently labeled mitochondria in a region of an axon in a fruit-fly larva; you have plotted the results in the following graph, in which the vertical axis is time (from the top to the bottom), the horizontal axis is the position along the axon, and each trace represents one mitochondrion. Is the retrograde transport or the anterograde transport of mitochondria faster in these axons? Does the trace indicated by an asterisk correspond to a mitochondrion that was transported by a dynein or a kinesin? 
A) Anterograde; kinesin 
B) Anterograde; dynein 
C) Retrograde; kinesin 
D) Retrograde; dynein

Quizplus · Accepted Answer

In this graph, the traces with a negative slope and indicated by thicker lines represent anterograde movement toward the axon terminal mediated by kinesins; those traces with a positive slope represent retrograde motion mediated by dynein. The speed is inversely related to the slope in this graph, and is higher for the retrograde movement.

Using Time-Lapse Fluorescence Microscopy, You Have Recorded the Transport of Fluorescently