Briefly answer the following questions: What are gap junctions composed of? What types (and sizes) of solute will they allow to pass between cells?

Briefly answer the following questions:

What are gap junctions composed of? What types (and sizes) of solute will they allow to pass between cells? What are their biological functions?

Tight junctions, What are tight junctions composed of and where are they found on epithelial cells?

What proteins are essential for their formation and which cytosolic proteins help to organize them?