Question

Describe experiments using marker molecules that have been done to elucidate important properties of (1) tight junctions and (2) gap junctions, and propose one additional experiment you could do with each junction to gain a greater understanding of that junction's properties.

Answer 1

Marker molecules have been used in experiments to study the barrier function of tight junctions and the communication role of gap junctions. Additional experiments could investigate the effect of protein expression changes on tight junction function and calcium wave propagation through gap junctions.

Step-by-step explanation:

Experiments on Tight Junctions and Gap Junctions,

Experiments using marker molecules have elucidated the properties of tight junctions and gap junctions. For tight junctions, one method involves the use of fluorescent molecules of different sizes. These molecules are applied to one side of a tissue, and their movement is monitored. Observations reveal that tight junctions prevent the passage of molecules, demonstrating their role as a barrier.

As for gap junctions, experiments often involve injecting dye into one cell and observing if it spreads to adjacent cells through the gap junction channels. This indicates that gap junctions allow the passage of small molecules and ions, facilitating intercellular communication.

An additional experiment for tight junctions could involve altering the expression of claudins and occludins to observe the effect on barrier function. For gap junctions, one could use genetically encoded calcium indicators to visualize intercellular calcium wave propagation, giving insight into the junction's role in cell signaling.