A researcher is carrying out an experiment where she labels a protein with a fluorescent tag (so she can visualize its location in a cell), and introduces this tagged protein into the lumen of a single thylakoid. She observes her treated cells periodically, and notices that the labeled protein can move between grana, but is never observed in the stroma. What can she deduce?
A)This protein can easily transfer between the inner and outer mitochondria membranes.
B)All thylakoid membranes and grana share a common lumen, through which the labeled protein can move.
C)This protein likely travels between different thylakoid membranes by moving through the stroma, but its movement through the stroma is very brief.
D)This protein cannot easily diffuse through the thylakoid membrane.
E)The protein likely travels through a common lumen shared by thylakoid membranes and grana, and cannot easily diffuse through the thylakoid membrane.

Question

Quizplus · Accepted Answer

The observation that the labeled protein can move between grana but not in the stroma suggests that it is traveling through a common lumen shared by thylakoid membranes and grana, rather than diffusing through the thylakoid membrane. This indicates that option B is correct. Option A can be ruled out as it is not related to the observation made in the experiment, and option C is unlikely since the researcher never observed the protein in the stroma. Option D can also be ruled out as the protein is observed to move between grana.

A Researcher Is Carrying Out an Experiment Where She Labels