Cytoplasm

Part true solution

Part polyphasic colloid (sol-gel)

ATP serves as energy currency of the cell

Principle energy source

Adenosine triphosphate

Hydrolyses to form ADP and Pi + energy

Desmosomes

Disk shaped areas where adjacent cells are separated by  20 nm and held together by cadherins

Tight junctions

Area where plasma membranes are in direct contact. (most common cellular junction)

Gap junctions

Connexin channels 1.5 nm in diameter directly link cytoplasm of 2 cells

Membranes are 2-4 nm apart. (most efficient)