Current is the key
Several differences distinguish the electrophoresis gel (our DNA race track) and a slab of gelatin you would eat for desert. The water used to make the gel has electrolytes in it to conduct current. This water plus electrolytes solution is called an electrophoresis buffer. An agarose gel is made of complex carbohydrates extracted from seaweed and is not sweet to eat. The matrix creates the right size spaces for sieving DNA and holds it's shape even if it heats up when electric current is run through it. Finally, the electrophoresis gel is placed in an electrophoresis apparatus or gel box that is designed to hold the gel in place and conduct a current through it.