If the cell membrane does not function normally it allows abnormal movement of substance in and out of the cell, lets take for example the movement of water of plasma membrane allows water to get in into the cell more than what is needed it might cause the bursting of the cell or if it allows water from the cell to get out and leaves only solute within this will cause shrinking of the cell wherein both conditions are abnormal
can you be more spacific please there are many answers to that question.
people must was there hands after every break and after handing food every product cut needs its own cutting board example meat cant be cut on the same board as potatos.