Well, one thing is that they both need organs or organelles to survive. Like your brain helps your body function, the nucleus of a cell helps the cell function.
Another thing that makes a cell and an organism are alike (in a relationship) is that they need energy. Your body makes energy with the food you eat that goes to the pancreas and that makes little atoms that goes to the cell, and the cell uses that insulin (energy) to function. Your body needs this to function as well.
